Fellow of the Rejal Society, and Member of the Society of Amiquaries, in Londort,

IN TWO VOLUMES.

LONDON;

Utrechts Univsrs�telts

IVii:s8iiro

MICROSCOPE

I. The Nature, XJfes, and Magnifying PoiverS of the beft Kinds of Microscopesnbsp;Dejcribed, Calculated, and Explained:

For the Inftrufliori of fuch, particularly, as defIre to fearch into the Wonders of the Minute Creation,nbsp;tho� they are not acquainted with O.pticsi

Full Dire�lions how to prepare^ apply, examine, and prefervl, all Sorts of Objects ;

A great Variety of new Experiments and Obfervationss pointing out many uncommon Siibjcfls for thenbsp;Examination of the Curious.

With an additional Plate of the Solar Microscope, and feme farther Accounts of the Polype.

Martin Folkes, .E/^;

COUNCIL and FELLOWS

AN Attempt to excite in Mankind a general De�re of fearch-ing into the Wonders of Nature, will, I perfuade myftlf, be acceptednbsp;favourably byyou, whofe Endeavoursnbsp;for the Advancement of Naturalnbsp;Knowledge, accordino; to the Pur-pofe of your Inftitution, are efteem-ed by all the World.

A3 nbsp;nbsp;nbsp;It

It is fomething more than an hundred and twenty Years fince the Microscope was happily invented;nbsp;and to the valuable Difcoveries madenbsp;thereby, we Hand indebted, as thenbsp;following Sheets will lliew, for a greatnbsp;Part of our prefent Philofophy. Innbsp;fuch a Length of Time, it is however probable, many more Advantagesnbsp;might have been reaped from it, hadnbsp;not fome Difficulties and Difcouragc-ments prevented its general Ufe.

At the Beginning it was confined to very few; who, making a Secretnbsp;of it, endeavoured all they could tonbsp;keep it to themfelves ; and, when itnbsp;became a little more publiek, thenbsp;Price was fixed fo high, that the moftnbsp;Curious and Induftrious, who have notnbsp;always the greateft Share of Money,nbsp;could not conveniently get at it.

DEDICATION. v�

Of late Years, indeed, the Expence has been much lefs ; but then newnbsp;Difcouragements have ftarted upnbsp;from Miftake and Prejudice.

For Many have been frighted from the Ufe of it, by imagining it required great Skill in Optics, andnbsp;Abundance of other Learning, tonbsp;comprehend it to any Purpofenbsp;whereas nothing is really needfulnbsp;but good Glades, good Eyes, a littlenbsp;Practice, and a common Underftand-ing, to diftinguiih what is feen ; andnbsp;a Love of Truth, to give a iaithfulnbsp;Account thereof. Others have con-iidered it as a mere Plav-thins;, anbsp;Matter of Amufement and Fancynbsp;only, that raifes our Wonder for anbsp;Moment, but is of no farther Service : which Miftake they have fallen into, from being unacquainted

via DEDICATION.

with any Principles whereby to foria a right Judgment of what they fee.nbsp;Many, again, have laid the Micro-^nbsp;fcope alide, after a little Ufe, fornbsp;want of knowing what Objeds tonbsp;examine, where to find, how tonbsp;prepare, and in what Manner to apply them. The Trouble of mana-^nbsp;ging it has alfo frighted fome.

But we are now fo fortunate as to have this Inftrument greatly improved amongfi; ourfelvcs, the Apparatusnbsp;made much eafier as w'ell as morenbsp;ufeful, and the Price confiderablynbsp;reduced. The Solar or Camera Ob-fcura Microfcope, and the Micro-fcope for viewing Objcds that havenbsp;no Tranfparency, by throwing anbsp;firong refieded Light upon them, arenbsp;alfo new Inventions, from whencenbsp;great Things may be expeded.

Nothing therefore is now want-r ins, but a general Inclination tonbsp;employ thefe Inftruments, for a far-^nbsp;ther Difcovery of the Minute Won^�nbsp;ders of the Creation ; which may notjnbsp;perhaps, improve our Knowledgenbsp;lefs than the grander Parts thereof,nbsp;Bears, Tigers, Lions, Crocodiles andnbsp;Whales, Oaks and Cedars, Seas andnbsp;Mountains, Comets, Stars, Worldsnbsp;and Suns, are the Capitals innbsp;Nature�s mighty Volume, and ofnbsp;them we fliould not be ignorant:nbsp;but whoever would read there withnbsp;Underftanding, mu ft make himfelfnbsp;Mafter of the little Letters like wife,nbsp;which occur a thoufand Times morenbsp;frequently, and, if he does not knownbsp;them, will ftop him fliort at �verynbsp;Syllable.

DEDICATION.

ing Truth, is, by the Experiments of Many upon the fame Subjed:; andnbsp;the moft probable Way of engagingnbsp;People in fuch Experiments, is, bynbsp;rendering them eafy, intelligible,andnbsp;pleafant. To effed this, is my Endeavour in the following Treatife,nbsp;which may ferve as the Reprefenta-tion of an Objed for the Inftruinentnbsp;I am recommending ; fmall, indeed,nbsp;and feemingly of no Gonfequcnce ;nbsp;but what, upon Examination, willnbsp;be found, perhaps, to contain asnbsp;many ufeful Parts as thofe that arenbsp;much bulkier: for, to drop the Allu-fion here, i am certain, that withnbsp;half the Pains I could have made it

Think me not fo prefumptuous, to dream of inftruding you, in Mattersnbsp;you are much better acquainted with

DEDICATION. xi than I can pretend to be; but givenbsp;me Leave to requefl: the Favour ofnbsp;your Concurrence, in my Defire ofnbsp;explaining, to thofe that are ignorant, a Science that may prove of thenbsp;moft eminent Service towards thenbsp;Advancement of True Knowledge,nbsp;and in wTich every body that hasnbsp;Inclination and Opportunity may benbsp;able to do fomething.

Excufe my Miftakes, forgive my detaining you thus long, and permitnbsp;me the Honour to be, with all pofli-ble Refpecl and Veneration,

Henry Baker,

(xiii)

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Contents of the Chapters.

PART the FIRST.

Chap, VIII. To find the magnifying Power oj Glajfes employed in Single Microfcopes 32nbsp;Chap. IX. The magnifying Power ofnbsp;Qlajfesin t he Double Microfcopenbsp;nbsp;nbsp;nbsp;3 9

Chap. nbsp;nbsp;nbsp;LI. 7he Works of Art and Nature cotnpared and conjiderednbsp;nbsp;nbsp;nbsp;292

( xvil )

oooo..J2..g8oo..^.-�eo ooto-^-goo�^oooo �n'�MeQquot;^�0()09lt;^-eooo-^^

INTRODUCTION.

N this inquifitlve Age, when the 11 I � �efire of Knowledge has fpreadnbsp;itfelf far and wide, and we fit notnbsp;down contented, as heretofore,nbsp;with the Opinions of ancient Times, butnbsp;refolve to examine for Ourfelves, and judgenbsp;from our own Experience ; it may not, perhaps, prove unacceptable to point out fomenbsp;proper Subjefbs of Enquiry.

The Works of Nature are the only Source of true Knowledge, and the Study of themnbsp;the moil; noble Employment of the Mind ofnbsp;Man. Every Part of the Creation demandsnbsp;his Attention, and proclaims the Power andnbsp;VoL.I,nbsp;nbsp;nbsp;nbsp;anbsp;nbsp;nbsp;nbsp;Wifdom

xvili. rhe INTRODUCTION. Wifdom of its Almighty Author. Thenbsp;fmallell; Seed, the minuteft Infedl, {hews thenbsp;Skill of Providence in the Aptnefs of itsnbsp;Contrivance for the Purpofes it is to ferve,nbsp;and difplays an Elegance of Beauty beyondnbsp;the utmoft Stretch of Art.

The Wife in all Ages have been fenfible of this Truth ; and, as far as they were able,nbsp;have ftudied and enquired into the Receflesnbsp;of Nature ; but for Want of proper Helpsnbsp;have frequently been milfaken. As certainnbsp;Principles mulf firft be learned ere w^e cannbsp;become Mailers of any Science, fo in thenbsp;School of Nature, we mull begin with thenbsp;Mmutice, the fmallell and moll uncompounded Parts, ere we can underlland thenbsp;larger and more conliderable.

The Ancients, having only their naked Eyes to trull to, were uncapable of anynbsp;great Difeoveries of this Sort: but we are lonbsp;happy, that, by the Help of GlalTes, we cannbsp;dillinguilh and examine Objedls many Thou-fands of Times lefs than what the diarpellnbsp;Eye, unaflided, can difeern. In lliort. Microscopes

T:he imROBUCriON. xix

CRoscoPES furnifli us as it were with a new Senfe, unfold the amazing Operationsnbsp;of Nature, and prefent us with Wondersnbsp;unthought of by former Ages.

Who, a thoufand Years ago, would have imagined it poffible to diftinguifla Myriadsnbsp;of living Creatures in a fingle Drop of Water ? Or, that the Purple Tide of Life, andnbsp;even the Globules of the Blood hiould benbsp;feen diftindily, rolling thro� Veins and. Arteries fmaller than the finefl Hair ? That Millions of Millions of Animalcules flaould benbsp;difcovered in the Semen Majcnlinum of allnbsp;Creatures? That not only the exterior Form,nbsp;but even the internal Strudlure of the Bowels, and the Motion of the F'luids in a Gnatnbsp;or Loufe, fhould be rendered Objeds ofnbsp;Sight ? Or, that numberlefs Species of Creatures hiould be made vhible, tho� lo minute,nbsp;that a Million of them are lefs than a Grainnbsp;of Sand ?

Thefe are noble Difcoveries, whereon a new Philofophy has been raifed, that enlarges the Capacity of the human Soul, and

XX �The INTRODUCTION.

furniflies a more juft and fublime Idea than Mankind had before, of the Grandeur andnbsp;Magnificence of Nature, and the infinitenbsp;Power, Wifdom, and Goodnefs of Nature�snbsp;Almighty Parent.

That Man is certainly the happieft, who is able to find out the greateft Number ofnbsp;reafonable and ufeful Amufements, eafily attainable and within his Power; and, if fo,nbsp;he that is delighted with the Works of Nature, and makes them his Study, muft undoubtedly be happy; fince every Animal,nbsp;Flower, Fruit, or Infedl, nay, almoft everynbsp;Particle of Matter, affords him an Entertainment. Such a Man never can feel hisnbsp;Time hang heavy on his Hands, or be wearynbsp;of himfelf, for want of knowing how tonbsp;employ his Thoughts : each Garden ornbsp;Field is to him a Cabinet of Curiofities,nbsp;every one of which he longs to examinenbsp;fully ; and he confiders the whole Univerfenbsp;as a Magazine of Wonders, which infinitenbsp;Ages are fcarce fufficient to contemplate andnbsp;admire enough.

The

The Invention of Glasses has brought under our Examination the two Extremes ofnbsp;the Creation, if I may be allowed to callnbsp;them fo, which were out of the Reach ofnbsp;former Ag-es: I mean, thofe vaft and diftantnbsp;Bodies of our Syllem, the Sun and Planets ;nbsp;whofe Dimenfions, Diftances, Motions, Regularity and Order, we are become acquainted with by the Help of Telescopes ; andnbsp;thofe exceedingly minute, and to them in-vifible, and unknown (though every wherenbsp;at Hand) Species of Animals, Plants, amp;c,nbsp;which the Microscope has difcovered tonbsp;us. I leave the Telescope to others, whonbsp;are better able to do it Juftice; my Intentnbsp;in this Difcourfe is to treat of the Microscope, and encourage its more general Ufe,nbsp;by fhewing the Pleafure and Initrudlion itnbsp;can afford us.

Mr. Boyle fays, in his Difcourfe of the Ufefulnefs of Experime}ttal Thilofophy, thatnbsp;his Wonder dwells not fo much on Nature�snbsp;Clocks as on her Watches j and, indeed, upon comparing the Structure of a Mite with

that

that of an Rlephant, I believe we fhall concur in the fame Opinion. The Largenefs and Strength of the one may ftrike us withnbsp;Wonder and Terror, but we fhall find our-ff^lves quite lofl in Amazement, if we attentively examine the hweral minute Parts ofnbsp;the other. For the Mite has more Limbsnbsp;than the Elephant, each of which is furnifh-ed with Veins and Arteries, Nerves, Mufcles,nbsp;Tendons, gnd Bones : it has Eyes, a Mouth,nbsp;and a Probofcis too (as well as the Elephant)nbsp;to take in its Food; it has a Stomach tonbsp;digefl it, and Inteftines to carry off what isnbsp;not retained for Nourifhment : it has annbsp;Heart to propel the Circulation of its Blood,nbsp;a Brain to fupply Nerves every where, andnbsp;Parts of Generation as perfedt as the largeftnbsp;Animal. Let us now flop, look back, andnbsp;confider, as far as our Abilities can reach,nbsp;the exceffive Minutenefs of all thefe Parts jnbsp;and if we find them fo furprizing and beyond our Ideas, what fhall we fay of thofenbsp;many Species of Animalcules, to whom anbsp;Mite itfelf, in Size, is as it were an Elephant ?

JN^RODUCriON. xxili

All thefe, and numberleft Wonders more, the Microscope can exhibit to us. I fhallnbsp;therefore proceed to defcribe this noble Invention, fhew how far it is improved atnbsp;prefent, give a brief Account of what Dif-coveries have been made, and point outnbsp;fome Objedls for the Curious to examinenbsp;by it. In doing this, I Ihall avoid as muchnbsp;as poffible all Affedlation of Learning, ornbsp;Expreffions that are not in common Speech,nbsp;being defirous that every body may underhand me.

THE

MICROSCOPE

CHAP. I.

Y Microscopes we are under-B ^ ftood to mean, Injlruments of what~gt; ever Stru�iure or Contrivance, thatnbsp;can make Jmall ObjeSls appear largernbsp;than they^ do to the naked Eye.

VoE. I. nbsp;nbsp;nbsp;Bnbsp;nbsp;nbsp;nbsp;When

When only one fuch convex Glafs or Lens * is ufed for this Intent, the Inflru-ment it is fixt in, however faihioned, isnbsp;called a Single Microfcope : but if two ornbsp;more GlalTes are employed, conjointly, tonbsp;magnify Objefts more, it is then called anbsp;Double or Compound Microfcope.

One remarkable Difference in the Effed: of thefe two Inftruments is, that an Objednbsp;viewed through a fingle convex Glafs appears magnified, in the fame Pofition exadlynbsp;as when leen by the naked Eye ; but whennbsp;viewed through a Double Microfcope, com-pofed of three convex Glafles, all Parts of itnbsp;become inverted ; that is, the Top of thenbsp;Objed appears at Bottom, the Right Side onnbsp;the Left, and every Part in the Place moftnbsp;oppofite to its natural and true Pofition :nbsp;The Lights and Shades being alfo inverted,nbsp;the finking Parts appear to rife, and thenbsp;rifing Parts to fink in.

� The Word Lens properly fignifies a fmall Glafs in Figure of a Lentil ; but is extended to any Optic Glafs not verynbsp;thick, which either collefts the Rays of Light into a Pointnbsp;in their Paflage through it, ordifperfes them apsrt, according to the Laws of Refradlion. If convex on both Sides, itnbsp;is called a Convex Lens ; but if one Side be flat, a Plano-Convex : If concave on both Sides, it is termed a Concavenbsp;l.ens; 'if flat on one Side, a Plano-Concave; if convex onnbsp;one Side, and concave on the other, a Convexo-Concave, ornbsp;Concavo-Convex.

of Microfcopes, is not in me to determine: the Honour has been given by fome tonbsp;Hrebbel, zDutc�mam by others to Fontana, a Neapolitan; and by others dill tonbsp;different People. The fird Appearance ofnbsp;them however was about the Year 1621 ;nbsp;dnce when they have been improving downnbsp;to the prefent Time.

As my Defire is, to make People fenfible of the Pieafure and Information the Micro-fcope can afford, and indrudl them how tonbsp;manage and underdand it, rather than hownbsp;to make it, I fhall take up none of theirnbsp;Time with the Manner of melting, grinding, polifhing, or fetting of Glades; a Worknbsp;very few of my Readers will ever troublenbsp;themfelves about. But, indead thereof, Inbsp;^alj endeavour, with all the Brevity andnbsp;Clearnefs I am able, to explain the Effedtsnbsp;of Glaffes on the Sight, and lead them gradually into the Nature, Ufes, and magnifying Powers of Microfcopes.

When Objedls are feen through a perfedlly flat Glafs, the Rays of Light pafs throughnbsp;It, from them to the Eye, in a drait Direction, and parallel to each other j and confe-quently the Objedts appear very little eithernbsp;diminifhed or enlarged, or nearer or farthernbsp;off, than to the naked Eye. But if thenbsp;Glafs they are feen through has any Degreenbsp;Convexity, the Rays of Light are diredt-from the Circumference towards thenbsp;E 2nbsp;nbsp;nbsp;nbsp;Center,

Centerj in an Angle proportionable to the Convexity of the Glafs, and meet in a Point,nbsp;at a greater or lefs Diftance from the Glafs, .nbsp;as it is lefs or more convex. This Point,nbsp;where the Rays meet, is called the Focus ;nbsp;and this Focus is nearer of farther off, according to the Convexity of the Glafs: fornbsp;as a little. Convexity throws it to a confi-derable Diftance, when the Convexity isnbsp;much, the Focus is very near. Its magnifying Power is alfo in the fame Proportionnbsp;to the Convexity: for as a flat Glafs magnifies fcarce at all, the lefs a Glafs departsnbsp;fromFlatnefs, the lefs ofcourfe it magnifies;nbsp;and the more it approaches towards a globular Figure, the nearer its Focus is, andnbsp;the more its magnifying Power.

People�s different Length of Sight depends on the fame Principle, and arifes from anbsp;more or lefs Convexity of the Cornea andnbsp;Cryjialline Humom of the Eye : the roundernbsp;thefe are, the nearer will the Foczis or Pointnbsp;of meeting Rays be, and the nearer an Ob-jeiSl muft be brought to fee it well. Thenbsp;Cafe of fhort-figh ted People is only an O ver-roundnefs of the Eye, which makes a verynbsp;near Focus; and that of old People is anbsp;Sinking or Flattening of the Eye, wherebynbsp;the Focus is thrown to a great Diftance :nbsp;fo that the former may properly be callednbsp;Eyes of too fliort, and the latter. Eyes of toonbsp;long a Focus. Hence too the Remedy for

Of Microscopes in General. 5 the laft is a convex Glafs, to fupply thenbsp;Want of Convexity in the Eye itfelf, andnbsp;bring the Rays to a fhorter Focus j whereasnbsp;a concave Glafs is needful for the firft, tonbsp;fcatter the Rays, and prevent their comingnbsp;to a Point too foon.

Nothing is morecommon than to obferve old People holding Objedls they would examine at a great Diftance from them, fornbsp;the Reafon above-mentioned j and everynbsp;body knows, fliort-lighted People cannotnbsp;diftinguifh any thing without bringing itnbsp;Very near their Eyes. Both Extremes arenbsp;inconvenient; but thofe whofe Eyes are flatnbsp;by Age Ihould remember with Satisfadlion,nbsp;that they have enjoyed the Pleafure of themnbsp;for many Years; and the Short-fighted maynbsp;comfort themfelves, that they can diftin-guifh much fmaller Objedts than long-flghted People: for the Objedt is magnifiednbsp;in Proportion to the Roundnefs of the Eyenbsp;and the Nearnefs of the Focus, and confe-quently appears four times as big to an Eyenbsp;whofe Focus is but four Inches off, as itnbsp;does to one whofe focal Diftance is at eightnbsp;Inches. They have alfo this farther Advantage, that Age improves their Eyes, by thenbsp;fame Means it impairs other People�s, thatnbsp;IS, by making them more flat.

The nearer any Objedt can be brought to the Eye, the larger will be the Angle undernbsp;which it appears, and the more it will be

the Eye at the Diftance of its Focus; wherefore the fmaller a Lens is, and the more its Convexity, the nearer is its Focus, and thenbsp;more its magnifying Power.

As it is an eafy matter to melt a Glafs Drop or Globule of a much fmaller Diameter than any Lens can poffiblybe ground,nbsp;and as the Focus of a Globule is no farthernbsp;off than one quarter of its own Diameter,nbsp;and confequently it muft magnify to a prodigious Degree, fome Years ago People werenbsp;extremely fond of fuch Globules, and imagined no good Microfeope could be withoutnbsp;them: but Experience has fince taught, thatnbsp;they admit fo little Light, can fhew fuchnbsp;an exceeding minute Part only of any Ob-iedl, are fo difficult to make ufe of, andnbsp;Itrain the Eyes fo much, that their Power ofnbsp;magnifying, for Want of due Diftindtnefs,nbsp;is rather apt to produce Error than difeover

Microscopes are cither Single or Double : the Single have but onenbsp;Lens j the Double are a Combination ofnbsp;two or more. Each of thefe two Kinds hasnbsp;its particular Advantage: for a fingle Glafsnbsp;Ihews the Objedl nearer at hand, and rather more diflind:; and a Combination ofnbsp;Glafles prefents a larger Field, or, in othernbsp;Words, exhibits more of an Objed, equallynbsp;magnified, at one View. It is difficult tonbsp;determine which of thefe to recommend,nbsp;fince each affords a different Kind of Plea-fure. Each of them too can produce confi-derable Authorities in its Favour ; for Mr,nbsp;Leeuwenhoek J never ufedany but fingle

t Several Writers xeprefent the Glaffes Mr. Leeuwenhoek made ufe of in his Microfcopes, to be little Globules or Spheres of Glafs ; which Miftake moft probably arifesnbsp;from their undertaking to defcribe what they had never fcen;nbsp;for at the Time 1 am writing this, the Cabinet of Micro-icopes left by that famous Man, at his Death, to the Roja/nbsp;Society^ a Legacy, is standing upon my Table ; and Inbsp;Mn alTure the World, that every one of the twenty-fixnbsp;Microfcopes contained therein is a double convex Lens,nbsp;and not a Sphere or Globule.

Microfcopes ; and, on the contrary, Mr. Hooke made all his Obfervations withnbsp;double ones.

The famous Microfcopes of Mr. Leeuwen h o e k are the moft Ample poffible, being only a Angle Lens, fet between twonbsp;Plates of Silver perforated with a fmallnbsp;Hole, with a moveable Pin before it, tonbsp;place the Objedl on, and adjuft it to thenbsp;Eye of the Beholder. By thefe he madenbsp;thofe wonderful Difcoveries which fur-prized the World fo much, and introducednbsp;a new SyAem of Philofophy and Reafon-ing, as in the Courfe of this Treatife I fliallnbsp;And OccaAon more at large to mention.

There are many pretty little Contrivances fold at the Shops for the viewing of fmallnbsp;Objeds, which are entertaining as far as cannbsp;reafonably be expefted from them: but tonbsp;enumerate all thefe would be a tedious TaAc.nbsp;It Aiould alfo be a Matter more of Curio-Aty than ProAt, to defcribe the Forms andnbsp;Apparatus of the fevcral Kinds of Microfcopes that have been contrived Ance thenbsp;Arft Invention of them. I Aiall thereforenbsp;conAne myfelf to give an Account of fuchnbsp;only in ufe among ourfelves at prefent, as,nbsp;by having a proper Set of GlaA'es, gradually magnifying one above another, are Atnbsp;to make Difcoveries of Confequence.

CHAP.

TH E firft that I (hall mention, is Mjr. Wilson�s Single Pocket Micro-�nbsp;/cope i the Body whereof, made either ofnbsp;Brafs,Ivory,or Silver, is reprefented(P/�/^I.)nbsp;by AA. BB.

CC. is a long fine-threaded male Screw, that turns into the Body of theMicrofcope.

* Two concave round Pieces of thin Brafs, with Holes of different Diameters in thenbsp;Middle of them, to cover the faid Glafs,nbsp;and thereby diminifh the Aperture, whennbsp;the greateft Magnifiers are employed.

EE. three thin Plates of Brafs within the Body of theMicrofcope, one whereof is bentnbsp;femicircularly in the Middle, fo as to formnbsp;an arched Cavity for the Reception of a Tubenbsp;of Glafs, whereas the two flat Plates are tonbsp;receive and hold the Sliders between them,

F. a Piece of Wood or Ivory, arched innbsp;the Manner of the femicircular Plate, andnbsp;cemented thereto.

G. the other End of the Body of the MI-crofcope, where a hollow female Screw isnbsp;adapted to receive the different Magnifiers.

H. nbsp;nbsp;nbsp;a fpiral Spring of Steel, between thenbsp;faid End G and the Plates of Brafs; intendednbsp;to keep the Plates in a right Pofition, andnbsp;counteract againft the long Screw CC.

I, nbsp;nbsp;nbsp;a fmall turned Handle, for the betternbsp;holding of the Inftrument, to fcrew on ornbsp;off at Pieafure.

To this Microfcope belong feven different tnagnifying Glaffes : fix of them are fet innbsp;Silver, Brafs, or Ivory, as in the Figure K,nbsp;and marked i. 2. 3. 4. 5. 6.; the loweftnbsp;Numbers being the greatefl Magnifiers.

L. nbsp;nbsp;nbsp;is the feventh Magnifier, fet in thenbsp;Manner of a little Barrel, to be held in thenbsp;Hand for the viewing any larger ObjeCt.

M. nbsp;nbsp;nbsp;is a fiat Slip of Ivory, called a Slider,nbsp;with four round Holes through it, wherein to place Objects between two Glaffes, ornbsp;Pieces of Miijcovy Talc, as they appearnbsp;d d d d.

Eight fuch Ivory Sliders, and one of Brafs, are ufually fold with this Microfcope;nbsp;fome with ObjeCls placed in them, andnbsp;others empty, for viewing any thing thatnbsp;may offer : but whoever pleales to make anbsp;large Collection of ObjeCts, may have asnbsp;many as he defires.

, The Brafs Slider is to confine any fmall Object, that it may be viewed withoutnbsp;crufhing or deflroying it.

N. nbsp;nbsp;nbsp;is a Forceps or Pair of Flyers, fornbsp;the taking up of InfeCts, or other ObjeCts,nbsp;and adjufling them to the Glafles.

O. nbsp;nbsp;nbsp;is a little HairBrulh or Pencil, wherewith to wipe any Dull from off the Glaffes,nbsp;or to take up any fmall Drop of Liquidnbsp;one would examine, and put it upon thenbsp;Talcs or Ifinglafs.

P. nbsp;nbsp;nbsp;is a Tube of Glafs, contrived to confine living Objedls, fuch as Frogs, Fifhes,

All thefe Particulars are contained in a little neat Box, very convenient for carrying in the Pocket.

When an Objed is to be viewed, thruft the Ivory Slider, in which the faid Objed isnbsp;placed, between the two flat Brafs Platesnbsp;EE: obfervingalways to put that Side of thenbsp;Slider where the Brafs Rings are, farthefl;nbsp;from your Eye. Then fcrew on the mag-nifying Glafs you intend to ufe, at the Endnbsp;of the Inftrument G ; and looking throughnbsp;it againfl; the Light, turn the long Screwnbsp;CC, till your Objed be brought to fit yournbsp;Eye i which you will know by its appearingnbsp;then perfedly diftind and clear.��Tis beftnbsp;to look at it firft, through a Magnifier thatnbsp;can (hew the Whole thereof at once, andnbsp;afterwards to infped the fcveral Parts morenbsp;particularly with one of the greateft Magnifiers : for thus you will gain a true Idea ofnbsp;the Whole, and of all its Parts. And tho�nbsp;the greateft Magnifiers can �hew but a minute Portion of any Objed at once, fuch asnbsp;8nbsp;nbsp;nbsp;nbsp;the

the Claw of a Flea, the Horn of a Loufe, or the like ; yet by gently moving the Slidernbsp;that contains your Objeft, the Eye willnbsp;gradually overlook it all : and if any Partnbsp;fhould be out of Diftance, the Screw CCnbsp;will eafily bring it to the true Focus.

As Objedls muft be brought very near the Glaifes when the greateft Magnifiers arenbsp;ufed, be particularly careful not to fcratchnbsp;them by rubbing the Slider againft themnbsp;as you move it in or out. A few Turns ofnbsp;the Screw CC will eafily prevent this Mif-chief, by giving them Room enough.

You may change the Objedls in your Sliders, for what others you think proper,nbsp;by taking out the Brafs Rings with thenbsp;Point of aPen-knifcj thelfinglafs will thennbsp;fall out, if you but turn the Sliders ; andnbsp;after putting what you pleafe between them,nbsp;by replacing the Brafs Rings, you willnbsp;fatten them as they were before. �Tis proper to have fome Sliders furnithed withnbsp;Talcs, but without any Objedls betweennbsp;them, to be always in Reaclinefs for thenbsp;F'xamination of Fluids, Salts, Sands, Powders, the Farina of Flowers, or any othernbsp;calual Objedts of fuch fort as need only benbsp;applied to the Outfide of the Talc.

The Circulation of the Blood may eafieft be feen in the Tails or Fins of Fifiies, in thenbsp;fine Membranes- between a Frog�sToes, or,nbsp;beft of all, in the Tail of a Water-Newt.

If your Objedt be a fmall Fifli, place it within the Tube, and fpread its Tail or Finnbsp;againft the Side thereof: if a P'rog, chufenbsp;fuch an one as can but juft be got into yournbsp;Tube, and with a Pen or Stick expand thenbsp;tranfparent Membrane between the Toes ofnbsp;the Frog�s hind Foot as wide as you are able.nbsp;^Vhen your Objedt is fo adjufted that nonbsp;Part thereof can intercept the Light fromnbsp;the Place you intend to view, unfcrew thenbsp;long fcrew CC, and thruft your Tube intonbsp;the arched Cavity, quite through the Bodynbsp;of the Microfcopej then fcrew it to the truenbsp;focal Diftance, and you will fee the Bloodnbsp;pafiing along its Veflels with a rapid Mo-^nbsp;tion, and in a moft furprifing Manner.

Make ufe of the third or fourth Magnifier for Frogs or Fifties j but for the Tails ofnbsp;Water-Newts, the fifth or fixth will do ;nbsp;hecaufe the Globules of their Blood arenbsp;twice as large as thofe of Frogs or Fifti.nbsp;The firft or fecond Magnifier cannot wellnbsp;he employed to this Purpofe; for theThick-nefs of the Tube wherein the Objedt lies,nbsp;will fcarce admit its being brought fonbsp;near as the focal Diftance of the Magnifier,

The Single Mic?'ofcope above de^sribed naay be formed into a Double One, by fcrew-ing it to a Tube with an Eye-Glafs at thenbsp;End thereof; it is alfo made to anfwer nearlynbsp;the Purpofes of the large Double Rejle^ingnbsp;Mkrofcope, by the Contrivance following.

CHAP.

CHAP. ly.

A new Invention for fixing the Pocket Microscope, and giving Light to it bynbsp;a Speculum. Plate II.

IN this Plate, A is a Scroll of Brafs, fixed upright on a round Pedellal of Woodnbsp;B, fo as to ftand perfectly firm and fteady.

C. is a Brafs Screw, that palfes through a Hole in the upper Limb of the Scroll,nbsp;into the Side of the Microfcope D, andnbsp;fcrews it fall to the faid Scroll.

E. a concaveLooking-glafs or Speculum, fet in a Box of Brafs, which hangs in thenbsp;Arch G, by two fmall Screws ff that fcrewnbsp;into the oppofite Sides thereof.

xA.t the Bottom of the faid Arch is a Pin of the fame Metal, exaftly fitted to a Holenbsp;h, in the wooden Pedefial made for the Reception of the faid Pin.

As the Arch turns on this Pin, and the Speculum turns on the Ends of the Arch, itnbsp;may, by this twofold Motion, be eafily ad-jufted, in fuch a manner, as to refleft thenbsp;Light of the Sky, the Sun, or a Candle,nbsp;directly upwards, thro� the Microfcope thatnbsp;is fixed perpendicularly over it; and, by fonbsp;doing, may be made to anfwer almofi: allnbsp;the Ends of the large Double RefieSiing Microfcope, which I fhall prefently defcribe. -

The Body of the Microfcope may alfo he fixt horizontally, and Objefts may benbsp;viewed in that Pofition, by any Light younbsp;choofe; which is an Advantage the Re-fledling Microfcope has not.

It may alfo be rendered farther ufeful, by means of a Slip of Glafs, one End of whichnbsp;being thruft between the Plates where thenbsp;Sliders go, afid the other extending to fomenbsp;Diftance, fuch �bjedls may be placed thereon, as cannot be applied on the Sliders:nbsp;and then, having a Limb of Brafs that maynbsp;fallen to the Body of the Microfcope, andnbsp;extend over the projefting Glafs a hollownbsp;Ring wherein to fcrew the Magnifiers, allnbsp;Sorts of Subjedls: may be examined withnbsp;great Conveniency, if a Hole be made innbsp;the Pedeflai, to place the Speculum exa�l-ly underneath, and thereby throw up thenbsp;Rays of Light.

The Pocket Microfcope thus fixt is, if I may prefume to judge, as eafy and pleafancnbsp;in its Ufe, and as fit for the moft curiousnbsp;Examination of the Animalcules and Salts innbsp;Fluids,,of the Farinas in Vegetables, of thenbsp;Circulations in fmall Creatures: in fliort, itnbsp;is as likely to make confiderable Difcoveriesnbsp;in Objedts that have fome Degree of Tranf-parency, as any Microfcope I have ever feennbsp;or heard of. It is alfo a material Part of thenbsp;Solary or Camera Obfcura Microfcopey whichnbsp;I fltall by and by defcribe.

CHAP.

Th E Double ReJleSling Microfcope in Ufe at prefent (whofe Picture withnbsp;its Apparatus is feen Plate III.) is an Alteration and Improvement, by Mr. Culpeper.nbsp;and Mr. Scarlet, of Mr. Marshal�snbsp;large Double Microfcope j than which it isnbsp;lefs cumberfome, may be managed withnbsp;much more Eafe, and, by means of a re-fle�led Light, is capable of Ihewing Objeftsnbsp;in a clearer and more pleafing Manner.

The Body of this Microfcope A A A A# being a large Tube, is fupported by threenbsp;Brafs Pillars bbb, rifing from a wooden Pe-deftal C i in which Pedeftal is a Drawer D,nbsp;to hold the Objelt;�t-Glaires and other Partsnbsp;of the Apparatus;

A leffer Tube, e e, Aides into the greater, and fends from its Bottom another Tubenbsp;much fmaller than itfelf, f with a malenbsp;Screw g, at the End thereof, whereon tonbsp;ferew the �bje�l-Glafs or Magnifier.

There are five of thefe Magnifiers, numbered I. 2. 3. 4. 5. which Numbers are alfo marked on the inner Tube, to direct whereabout to place it according to the Magnifiernbsp;made ufe of: but if then it fits not the Eyenbsp;exailly, Aide the inner Tube gently higher

'The Trouble ReJ�eSiing Microfcope. 17 or lower, turn the Screw of the Magnifier,nbsp;gradually, till the Objeft appears dillin�l.�nbsp;Take Notice, that the greateft Magnifiersnbsp;have the fmallefi; Apertures and the lowed:nbsp;Numbers.

L- is a circular Plate of Brafs, fixt horizontally between the three Brafs Pillars ; ^od in the Center thereof a round Hole M.nbsp;Js adapted to receive a proper Contrivancenbsp;N. for holding Ivory Sliders, wherein Objects are placed : which Contrivance con-hfts of a fpiral Steel Wire confined betweennbsp;three Brafs Circles, one whereof is mov�-able for the Admiffion of a Slider,

O. is a round Brafs Plate, with feveral Holes for placing Objedls in, fome of whichnbsp;sreufuallyfurniilred with them at the Shops:nbsp;out two Holes are commonly referved fornbsp;^all concave Glafles, whereon to place anbsp;Hrop of any Liquid, in order to view thenbsp;Animalcules, amp;c. There is alfo a Piece ofnbsp;white Ivory, and a Piece of black Ebony,nbsp;of the fame Size and Shape as the Ploles fornbsp;Objeils: the Ivory is to put opake Objeilsnbsp;on that are black, and the Ebony is to re-opive fuch as are white ; by which Contrariety of Colours they will be feen more

1 late is a Button, to flip into a Slit P. that fits It, on the circular Plate of Brafs: and bynbsp;turning it round on this Pin, all the Objedls

18 �I'he Double ReJleBing Microfcofe. may be examined fucceffively with very little Trouble.

is a concave Looking-glafs, fet in a Box of Brafs, and turning in an Arch R.nbsp;upon two fmall Screws s s. From the Bottom of the Arch comes a Pin, which, be-ine let down into a Hole t, in the Centernbsp;of the Pededal, enables the Looking-glafs tonbsp;turn vertically, or horizontally, and refledlnbsp;the Light, either of a Candle, or the Sky,nbsp;directly upwards on theObjedtto be viewed.

V. is a plano-convex Lens, which by turning on two Screws*'*, when the Pin atnbsp;the Bottom of it is placed, the Hole W. fornbsp;its Reception in the circular Plate L. willnbsp;tranfmit the Light of a Candle, to illuminatenbsp;any opake Objedt that is put on the roundnbsp;Piece of Ivory, or on the Ebony, for Examination : and it may be moved higher or lower as the Light requires. This Glafs is ofnbsp;good Service to point the Sunihine, or thenbsp;Light of a Candle, upon any opake Objedl;nbsp;but in plain Day-light it is of no great Ufe.

X. a Cone of black Ivory, to faften on a Shank underneath the Brafs circular Platenbsp;L. principally, when the firft or fecondnbsp;Magnifier is made ufe of, and the Objedtnbsp;very tranfparent: for Experience teaches,nbsp;that fuch Objects are rendered much morenbsp;dilfindfly vifible, by intercepting fome Partnbsp;of the oblique Rays refledted from the concave Looking-glai�s.

The Brafs Fifli-pan Y .is to faflen a Smelt, Gudgeon, or any fuch final] Fifh upon, tonbsp;lee the Blood circulate in its Tail. Fornbsp;which Purpofe, the Tail of the FiOa mullnbsp;he fpread acrofs the oblong Hole at thenbsp;fmalleft End of the Pan : then, by flippingnbsp;the Button on the Backfide of the Pan intonbsp;the Slit P. through the circular Plate L. thenbsp;Spring that comes from the B u t ton will makenbsp;It fteady, and prefent it well to View.

But if it be a Frog, a Newt, or Eel, in which the Circulation is deflred to be fliewn,nbsp;'�i Glafs Tube i. is fitteft for the Purpofe.nbsp;The Tail of a Newt, or Eel, or, in a Frog,nbsp;the Web between the Toes of the Hind-�^eet, are the Parts where it may be feennbsp;heft. When the Obje�t is well expanded onnbsp;the Infide of the T ube. Aide the T ube alongnbsp;Under the circular Brafs Plate L. (wherenbsp;there are two Springs and a Cavity made innbsp;the Shank to hold it) and bring your Ob-diredtly under the Magnifier.

There are three of thefe Glafs Tubes, hiialler one than another, and the Size ofnbsp;the Obje�t muft diredl which to ufej but innbsp;general, the lefs Room the Creature has tonbsp;move about in, the eafler it may be ma-uaged, and the quieter it will lie to benbsp;managed.

The Cell 2. with a concave and a plain Glafs in it, is intended to confine Fleas,nbsp;Lice, Mites, or any fmall living Objedls,nbsp;C 2nbsp;nbsp;nbsp;nbsp;during

during Pleafure ; and by placing it over th� Hole M. in the Middle of the circular Brafsnbsp;Plate, they may be vlew'ed with rhuch Con-

plain, and two concave, belong alfo to this Microfcope, and are defigned to coniinenbsp;Objects, or place them upon dccalionally.

The long Steel Wire 3. with a Pair of Plyers at one End, and a Point at the other#nbsp;to hold fall, dr Hick Objefts on, flip back-vt^ards dr forwards in a Brafs lliort Tube,nbsp;w'hereto a Button is faflened, which fitsnbsp;into the little Hole z, near the Edge of thenbsp;Brafs Plate L : and, then, the Objedt maynbsp;be readily brought to a right Pofitidn, andnbsp;a Light be call upon it, either by the Look-ing-glafs underneath, or, if it be opake, bynbsp;the plano-convex Lens V.

4. is a flat Piece of Ivdry called a Slider, with four round Holes through it, arid Ob-jedls placed in them between Mufcovy Talcsnbsp;or Ifinglafs, kept in by Brafs Wires.

It is proper to have a Number df thcfe Sliders filled with curious Objedls, alw'aysnbsp;1�eady, as well as fome empty ones, for anynbsp;new Thing that offers. When made ufe of,nbsp;tbruft: them between th� Brafs Rings ofnbsp;the Contrivance on purpofe for them, N.nbsp;which Ihoots into the round Hole M. innbsp;the Center of the Brafs Plate L. Thisnbsp;keeps them fteady, and at the fame timenbsp;permits them to be moved to and fro for anbsp;thorough Examination.

6, nbsp;nbsp;nbsp;a fmall Hair Brufh, to \vipe any Duftnbsp;off the Glafs, or to apply a Drop of anynbsp;Liquid.

7. nbsp;nbsp;nbsp;A Pair of Nippers, to take up any Ob-?nbsp;je6f to be examined.

The two Microfcopes I fhall defcribe next, viz. the Solar, or Camera Obfcuranbsp;Microfcope, and the Microjcope for Opakenbsp;Obje�is, are of a foreign Invention, and butnbsp;lately known to us. We are, indeed,nbsp;obliged for them both to a Gentleman �fnbsp;Rrifia, the ingenious Dr. Liberkhun,nbsp;who, when he was in England, in the Yearnbsp;1740, (hewed aii Apparatus for each ofnbsp;thefe Purpofes to feveral Gentlemen of thenbsp;Royal Society, and alfo to fome Opticians 5nbsp;amongft whom, Mr. Cuff, againft Ser~nbsp;jea7if s Inn Gate, in Fleet-Street, has takennbsp;great Pains to improve and bring them tonbsp;Perfedtion : and therefore I (hall give anbsp;Hefcription of them, as made and fold bynbsp;him. �nbsp;nbsp;nbsp;nbsp;'

TH IS Microfcope depends on the Sun-(hine, and niuft be made ufe of in a darkened Chamber, as its Name implies.

It is compofed of a Tube, a Looking�-glals, a convex Lens, and Wilson�s Single Pocket Microfcope before defcribed, p. g.

The Sun�s Rays being dire�ted by the Looking-glafs through the Tube upon thenbsp;Obje�l, the Image or PitSure of the Objedtnbsp;is thrown, diflindtly and beautifully, uponnbsp;a Screen of white Paper, or a white Linennbsp;Sheet, placed at fome Diftance to receivenbsp;the fame ; and may be magnified, to a Sizenbsp;beyond the Imagination of thofe who havenbsp;not feen it: for the farther olFthe Screen isnbsp;removed, the larger will the Objedl appear;nbsp;ini�omuch that a Louie may be magnifiednbsp;to the Length of five or fix Feet, or even anbsp;great deal more : but it is indeed more dif-tindt, when not enlarged to above half thatnbsp;Size *.nbsp;nbsp;nbsp;nbsp;The

�* Having, in the jecond Edition of this W'ork, inferted a, curious Draught of the Solar Microfcope, which was not innbsp;the former Itnprcflion, and given a more particular Description of that Inilrunient, and its Apparatus, than Inbsp;poilibly could before : lell the Purchafers of the firji Editionnbsp;foould have found Reafon t.0 complain of being unkindly

The Apparatus for this Purpofe, as represented in the Plate annexed, is as follows.

A. a fquare wooden Frame, thro� which two long Screws pafs, and, affifted by a couple of Nuts 1. I. fallen it firmly to a Win-dow-lhutter, wherein a Hole is made fornbsp;its Reception ; the two Nuts being let intonbsp;the Shutter, and made fall thereto.

A circular Hole is made in the Middle of this Frame, to receive a Piece of Wood of anbsp;circular Figure, B, whole Edge, that pro-jefts a little beyond the Frame, compofes anbsp;lhallowGroove 2, wherein runs aCat-gut 3;nbsp;�which, by twilling round, and then crolfingnbsp;over a Brafs Pully 4 (the Handle whereof,

palTes thro� the Frame) affords an eafy Motion for turning round the circularnbsp;Piece of Wood B, with all the Parts thereto affixt.

C. is a Brafs Tube covered with Seal-Skin, which, fcrewing into the Middle of the circular Piece of Wood, becomes anbsp;Cafe for the uncovered Brafs Tube D. tonbsp;he drawn backwards or forwards in.

E. a fmaller Tube of about one Inch in Length, cemented to the End of the largernbsp;Tube D.

t care that the faid Drawing and Defcription, with what other little Additions appeared neceflary to rendernbsp;the book more perfedl, Ihould be prefented to them gratis,nbsp;upon applying to thofe they bought them of. But no fuel;nbsp;Care IS requifite at prefent, this Impreffian being printed fromnbsp;t-nt fetortd, without any Difference of Confequence.

F. nbsp;nbsp;nbsp;is another fhort Brafs Tube, made tonbsp;flide over the above-defcribed Tube E. Tonbsp;the End hereof the Microfcope mufh benbsp;fcrewed when we come to ufe it.

5. a convex Lens, whofe Focus is about twelve Inches, deiigned to colled; the Sun�snbsp;Rays, and throw them more iirongly uponnbsp;the Objed:.

G. nbsp;nbsp;nbsp;a Looking-glafs of an oblong Figure,nbsp;fet in a wooden Frame, faftened by Flingesnbsp;to the circular Piece of Wood B, and turning about therewith, by Means of the above-mentioned Cat-gut.

H. nbsp;nbsp;nbsp;a jointed Wire, partly Brafs and partlynbsp;Iron ; the Braf^ Part whereof, vyhich is flat,nbsp;6, being falfened to the Looking-glafs, andnbsp;the Iron Part, which is round., 7, paffingnbsp;through the wooden Frame, enable thenbsp;Obferver (by putting it backwards or forwards) to elevate or decline the Glafs according to the Sun�s Altitude. ,

I. nbsp;nbsp;nbsp;a Brafs Ring at the End of the jointednbsp;Wire, whereby to manage it v/ith the greater Eafe.

JV. B. The Extremities of the Cat-gut are faftened to a Brafs Pin, by turning ofnbsp;which it may be braced up, if at any time itnbsp;becomes too flack. This Pin lying behind, could not be fhewn in the Pid:ure.

When this Microfcope is employed, the Room muft be rendered as dark as poflible rnbsp;for on the Darknefs of the Room, and

the Brightnefs of the Sun-fhine, depend the Sharpnefs and Perfedtion of your Image.nbsp;Then putting theLo�king-glafsG. throughnbsp;the Hole in your Window-jliutter, faftennbsp;'the fquare Frame A. to the faid Shuttefnbsp;by its two Screws and Nuts i. i.

This done, adjufty.our JLooking-glafs to, the Elevation and Situation of the Sun, bynbsp;Means of the jointed Wire H. together withnbsp;the Cat-gut and Fully, 3. 4. For the firftnbsp;of thefe raifing or lowering the Glafs, an^nbsp;the other inclining it to either Side, therenbsp;refults a twofold Motion, which may ealilynbsp;be fo managed as to bring the Glafs to anbsp;right Pofition, that is, to make it refiedt thenbsp;Sun�s Rays diredlly through the Lens 5.nbsp;upon the Paper Screen, and form thereonnbsp;a Spot of Light exadlly round

As foon as this appears, fcrew the Tube C. into the Brafs Collar provided for it innbsp;the Middle of your Wood-work, takingnbsp;Care not to alter your Looking-glafs: thennbsp;fcrewing the Magnifier you chufe to employ to the End of your Microfcope, in the

* Though obtaining a perfedt circular Spot of Light ppon the Screen, before you apply the Microfcope, is anbsp;certain Proof that your Looking-glafs is adjufted right,nbsp;that Proof muft not always be expected : for the Sun is fonbsp;Jow in Winter, that if it ihines in a direct Line againft thenbsp;Window, it cannot then afford a Spot of Light exaftlynbsp;round. But if it be on either Side of you, a round Spotnbsp;Play be obtained even in Dtcemicr,

ufual Manner, take away the Lens at the other End thereof, and piace a Slider, containing the Objedt to be examined, betweennbsp;the thin Brafs Plates, as in the other Waysnbsp;of ufing the Microfeope.

Things being thus prepared, ferew the Body of your Microfeope to the fhort Brafsnbsp;Tube F. which flip over the fmalleftEnd E.nbsp;of the Tube D. and pull out the faid Tube

D. nbsp;nbsp;nbsp;lefs or more, as your Obje(5l is capable ofnbsp;enduring the Sun�s Heat. Dead Objedlsnbsp;maybe brought within about an Inch of thenbsp;Focus ol the convex Lens, 5 ; but the Dif-tance mud be ihortened for living Creatures, or they will foon be killed.

If the Light falls not exadlly right, you may eafily, by a gentle Motion of the jointed Wire and Fully, diredl it through thenbsp;Axis of the microfcoptic Lens.

The fhort Tube F. which your Microfeope is ferewed to, enables you, by Aiding it backwards or forwards on the other Tube

E. nbsp;nbsp;nbsp;to bring your Objedfs to their true focalnbsp;DiAance; which will be known by thenbsp;Sharpncls andClearnefs of theirAppearance:nbsp;they may alfo be turned round by the famenbsp;Means, without being in the lead difordered.

The Magnifiers moil ufeful in the Solar Microfeope are, in general, the fourth,nbsp;fifth, or lixth.

it is proper to inform the Reader, that fuch a Screen is ufually compofed of a Sheet ofnbsp;the largeft Elephant Paper, ftrained on anbsp;Frame, which Aides up or down, or turnsnbsp;about at Pleafure on a round woodpn Pillar,nbsp;in the Manner of fomeFire-fcreens. Largernbsp;Screens are likewife made fometimes withnbsp;feveral Sheets of the fame Paper palled together on Cloth, and let down from thenbsp;Cieling with a Roller, like a large Map-;

This Microfcope is the moft entertaining of any ; and, perhaps, the moft capable ofnbsp;making Difcoveries, in Objedls that are notnbsp;too opake ; as it thews them much largernbsp;than can be done any other Way. Therenbsp;are alfo feveral Conveniences attending it,nbsp;which no other Microfcope can have : fornbsp;the weakeft Eyes may ufe it without thenbsp;leaft Straining or Fatigue: Numbers of People may view any Obje�l together at thenbsp;fame Time, and, by pointing to the particular Parts thereof, and difcourfing on whatnbsp;lies before them, may be able better to un-derfland one another, and more likely tonbsp;find Out the Truth, than when, in othernbsp;Microfcopes, they mull peep one after another, and perhaps fee the Objedt neither innbsp;the fame Light, nor the fame Polition. Suchnbsp;too as have no Skill in Drawing, ma)r, bynbsp;this Contrivance, eafily Iketch out the exa(Snbsp;Figure of an Objedt they have a Mind tonbsp;jpreferve a Pidture of; fince they need only

26 Of the Solar Microscope. faflen a Paper upon the Screen, and trace iifnbsp;out thereon, either with a P^n or Pericil, asnbsp;it appears before thern.

It is worth their while, who are defirous to take many Draughts this Way, ^o get anbsp;Frame, wherein a Sheet of Paper may benbsp;put or taken out at Pleafure ; for if thenbsp;Paper be fingle, the Image of an (3bie6tnbsp;will be fcen as plainly almoft on the backnbsp;as on the fore Side, and, by handing bcrnbsp;hind the Screen, the Shade of the Handnbsp;will not obdrudt the Light in Drawing, a?nbsp;it mulb in fome Degree when one handsnbsp;before it.

I muh obferve, that Dr. Liberkhun's Solar Microlcope had no Looking glafsnbsp;belonging to it, and therefore was of Ufenbsp;a few Flours pnly in a Day, when the Tubenbsp;could be placed diredlly againh the Body ofnbsp;the Sun, and even then not without a goo^nbsp;deal of Trouble: but, by this lucky Contrivance of a Looking-glafs, the Sun�snbsp;Rays may be refledled through the Tube,nbsp;whatever its Height or Situation be, provided it fhines at all upon the Window,nbsp;and that too with much E^fe and Advantage.

CHAP,

CHAP. VH.

This Milt;irofcope remedies the Inconvenience of having the dark Side of an Objedt next the Eye, which has hithertonbsp;been an unfurmountable Obftrudtion to thenbsp;making Obfervations on opake Objefhsnbsp;with any conflderable Degree of Exadlnefsnbsp;or Satisfadlion; for in all other Contrivances commonly known, the Nearnefs of thenbsp;Inftriiment to the Objedl (when GlalTesnbsp;that magnify much are ufed) unavoidablynbsp;overfhadows it fo niuch, as to render itsnbsp;Appearance obfcure and undiftindl. And,nbsp;notwitliftanding Ways have been tried tonbsp;point Light upon an Objedt, from the Sunnbsp;or a Candle, by a convex Glafs placed onnbsp;the Side thereof, the Rays from either cannbsp;be thrown upon it in fuch an acute Anglenbsp;only, that they ferve to give a confufednbsp;Glare, but are infufficient to afford a clearnbsp;and perfedt View of the Objedt.

But in this new Microfcope, by means of a concave Speculum of Silver, highly po-liflied, in whofe Center a magnifying Lensnbsp;is placed, fo diredt and ftrong a Light isnbsp;refledted upon the Objedl, that it may benbsp;examined with all imaginable Eafe andnbsp;Pleafure,

The Apparatus for this Purpofe (as in the Plate, Numb. IV.) has afforded me morenbsp;Delight and Satisfadlion than I am able tonbsp;defcribej and whoever tries it, will, I believe,nbsp;join in my Opinion, that he never beforenbsp;faw an opake Obje�t with fo much Clear-'nefs, and in fo perfedl and true a Manner.

The feveral Parts of this Inftrument, made either of Brafs or Silver, are as follows.

Through the firft Side A. paffes a fine Screw B. the other End whereof is faffen-cd to the moveable Side C.

D. nbsp;nbsp;nbsp;is a Nut adapted to the faid Screw,nbsp;by the turning of which the two Sides A.C.nbsp;are gradually brought together.

E. nbsp;nbsp;nbsp;is a Spring of Steel, that feparates thenbsp;faid two Sides when the Nut is unfcrewed.

F. nbsp;nbsp;nbsp;a Piece of Brafs turning round in anbsp;Socket, whence proceeds a fmall Springnbsp;Tube moving upon a Rivet, through whichnbsp;Tube there runs a Steel Wire, one Endnbsp;whereof terminates in a fharp Point G. andnbsp;the other hath a Pair of Plyers H. faffenednbsp;to it.�The Point and Plyers are to thruftnbsp;into or take up and hold any Infedt or Ob-jedl: and either of them may be turned upwards, as fuits your Purpofe beft.

I. a Ring of Brafs, with a female Screw within it, mounted on an upright Piece ofnbsp;the fame Metal, which turns round on anbsp;Rivet, that it piay be fet at a due Diftance

when the leaft Magnifiers are employed.� This Ring receives the Screws of all thenbsp;Magnifiers.

K. a concave Speculum of Silver, polifii-ed as bright as poflible, in the Center ofnbsp;which a double convex Lens is placed, withnbsp;a proper Aperture to look through it.nbsp;On the Back of this Speculum a male Screw

L. is made fit to the Brafs Ring I. to fcrewnbsp;into the faid Ring at Pleafure.

There are four of thefe concave Specula, of different Depths, adapted to four Glaflesnbsp;of different magnifying Powers, to be ufednbsp;as Objedls to be examined may require.nbsp;The greateft Magnifiers are known bynbsp;having the lead; Apertures.

M. a round Objedt-Plate, one Side whitenbsp;and the other black, intended to render Ob-jedts the more vifible, by placing them, ifnbsp;black on the white, and if white on thenbsp;black Side. A Steel Spring N. turns downnbsp;on each Side to make any Objedf faft:: andnbsp;iffuing from the Objedt-Plate is a hollownbsp;Pipe, to fcrew it on the Needle�s Point G.

O. nbsp;nbsp;nbsp;a fmall Box of Brafs, with a Glafs onnbsp;each Side, contrived to confine any livingnbsp;Obje(3:,in order to examine it: this alfohasanbsp;Pipe to fcrew upon the End of the Needle G.

P. nbsp;nbsp;nbsp;a turned Handle of Wood, to fcrewnbsp;into the Inftrument when it is made ufe of.

Q. nbsp;nbsp;nbsp;a Pair of Brafs Plyers, to take up anynbsp;Objed:, or manage it with Conveniency.

R. nbsp;nbsp;nbsp;a foft Hair Brufh, to clean the Glaflesnbsp;or Specula, �f apply amp; Drop of any Liquidnbsp;to the Ifinglafs of the Box O. in order tonbsp;view the Anirtialcuies.

S. nbsp;nbsp;nbsp;a fmali Ivory Box for liihglaffes, to benbsp;placed, when wanted, in the fmali Brafsnbsp;Box O.

When you would view any Objedt, fcrew the Speculum, with the Magnifier you thinknbsp;heft to ufe, into the Brafs Ring I. Place yournbsp;Objedt either on the Needle G. in the Flyersnbsp;H. on the Objedl-Plate M. or in the Brafsnbsp;holl�w Box O. as may be moll: convenient,nbsp;according to theNature and Condition of it;nbsp;then holding Up your Inflrument by thenbsp;Handle P. look againft the Light, throughnbsp;the magnifying Lens, and by means of thenbsp;Nut D. tosether with the Motion of thenbsp;Needle, by managing its lower End, thenbsp;Objedl may be turned about, raifed, or de-prefTed, brought nearer the Glafs, or putnbsp;farther from it, till you hit the true focalnbsp;Diflance, and the Light be feen refledlednbsp;from the Speculum ftrongly upon the Ob-jedt: by which means it will be flrewn innbsp;a Manner furprifingly diftindl and clear.nbsp;And, for this Purpofe, the Light of the Sky,nbsp;or of a Candle, will anfwer to your Satif-fadlion.

This Microfcope is principally intended for opake Objedls, but tranfparent ones maynbsp;alfo be viewed by it: obferving only, that

when fuch come under Examination, it will not always be proper to throw on them thenbsp;Light reflected from the Speculum : for thenbsp;Light tranfmitted through them meeting thenbsp;refleited Light, may, together, produce toonbsp;great a Glare. A little Practice will teachnbsp;how to regulate both thefe Lights to goodnbsp;Advantage.

There is Reafon to expedl great Difcove-ries may be made by the Apparatus above defcribed, as opake Obje�ls are a large Field,nbsp;but little hitherto examined, by reafon ofnbsp;the great Difficulty in doing it.

Having given a Defcription of the feveral Sorts of Microfcopes in Ufe amonglf us atnbsp;prefent, and (hewn what particular Advantages may be expedled from each, i fhallnbsp;proceed to inftrud; the Ignorant in thefenbsp;Things, with all the Clearnefs I can, to findnbsp;out the magnifying Powers of the Giaifesnbsp;they make ufe of, and calculate how manynbsp;Times they enlarge the Diameter, the Superficies, and the Cube ¹ or fohd Square of anynbsp;Objeft under Examination. And this, Inbsp;perfuade myfelf, will be highly fatisfadlory.

Some, perhaps, may diflike my fuppofing the Cube cf an Objedt to be magnified, firce, in reality, the Superficiesnbsp;only can be feen : but ihe Neceffity of fuch a Suppofition willnbsp;appear plainly in the Piogrefs of this Woik, when we comenbsp;to confider the true Size of Microfcopical Objedls, by comparing them with larger Bodies.

2 2 ^he Magnifying Power of Glajjes. and induce many People to be fond of thisnbsp;mofi delightful and inftrudlive Study, whennbsp;the Difficulties they imagined in it are removed, and they perceive it to be as eafy asnbsp;it is pleafant �, when they find themfelvesnbsp;able to judge of what they fee, not by merenbsp;random Guefs, but by certain and plainnbsp;Principles.

CHAP. VIII.

l�o find the Magnifying Power of GlaJJes eni-� ployed in Single Microficopes.

TH E Appearance of any Objedl, as to Magnitude, is according to the Anglenbsp;it is feen under ; or, in other Words, according to the Nearnefs it can be broughtnbsp;to the Eye : for the lefs the Diftance it cannbsp;be viewed at is, the more it will appear enlarged.

The naked Eye is unable to difunguiffi any Objedl brought exceedingly near it: butnbsp;looking through a convex Lens, howevernbsp;near the Focus of that Lens be, there annbsp;Objeft maybe diftinCtlyfeen t and the fmallernbsp;the Lens is, the nearer wnll be its Focus,nbsp;and in the fame Proportion the greater mufi'nbsp;be its magnifying Power.

From thefe Principles, it is eafy to find the Reafon why the firfi; or greateft Magnifiers are fo extremely minute ; and alfo tonbsp;calculate the magnifying Power of any convex Lens employed fingly in a Microfeope.nbsp;For fuch as the Proportion of the naturalnbsp;Sight to the Focus of the Lens is, fuch willnbsp;be its Power of magnifying. If the Focusnbsp;of a convex Lens (for Example) be at onenbsp;Inch, and the natural Sight at eight Inches,nbsp;which is the common Standard, an Objedlnbsp;may be feen through that Lens at one Inchnbsp;diftant from the Eye ; and will appear, innbsp;its Diameter, eight Times larger than to thenbsp;naked Eye, But as the Objedl is magnifiednbsp;every Way equally, in Length as well asnbsp;Breadth, we muft fquare this Diameter, tonbsp;know really how much it appears enlarged;nbsp;and we fhall then find, that its Superficiesnbsp;is indeed magnified fixty-four Times.

Again : Suppofe a convex Lens whofe Focus is at one Tenth of an Inch diftantnbsp;from its Center : in eight Inches there arenbsp;eighty fuch Tenths of an Inch j and therefore an Objedl may be feen through thisnbsp;Lens eighty Times nearer than it can dif-tmcftly by the naked Eye. It will confe-quently appear eighty Times longer, andnbsp;eighty Times broader, than it does to common Sight; and as eighty multiplied bynbsp;eighty makes fix thoufand and four hundred,nbsp;ib many Times it really appears magnified.

To go one Step farther : If a convex Glafs be fo fmall, that its Focus is no more thannbsp;one twentieth of an Inch diftantwe fhallnbsp;find that eight Inches, the common Difgt;nbsp;tance of Sight, contains an hundred and fix-ty of thefe twentieth Parts �, and, in Confe-quence, the Length and Breadth of an Ob-^edl, when feen through fuch Lens, will eachnbsp;be magnified an hundred and fixty Times ;nbsp;which multiplied by an hundred and fixty,nbsp;to give the Square, will arriount to twenty-five thoufand fix hundred quot;j and fo manynbsp;Times, it is plain, the Superficies of the Ob-jedl mufi; appear larger than it does to thenbsp;naked Eye at the Diflance of eight Inches.

Therefore, in a fingle Microfcope, to learn the magnifjdng Power of any Glafs,nbsp;no more is necefifary than to bring it to itsnbsp;true Focus; the exadt Place whereof willnbsp;be known, by an Objed�s appearing perfed-ly diftind and fliarp when placed there.nbsp;Then, with a Pair of fmall Compaffes, mea-fure, as nearly as you can, the Diflance fromnbsp;the Center of the Glafs to the Objed younbsp;was viewing, and afterwards applying thenbsp;Compaffes to any Ruler with a diagonalnbsp;Scale of the Parts of an Inch marked on it,nbsp;you will eafily find how many Parts of annbsp;Inch the faid Diflance is: When that isnbsp;known, compute how many Times thofenbsp;Parts of an Inch are contained in eightnbsp;Inches, the common Standard of Sight, andnbsp;8nbsp;nbsp;nbsp;nbsp;that

that will give you the Number of Times the Diameter is magnified : fquaring the Diameter will give you the Superficies; and ifnbsp;it be an Objeil whofe Depth or whole Contents you would l.;arn, multiplying the Superficies by the Diameter will fhew the Cubenbsp;or Bulk.

The Superficies of one Side only of an Object can be feen at one View; and tonbsp;compute how much that is magnified, isnbsp;mod commonly fufiicient. But fometimesnbsp;it is fatisfadlory to know how many minutenbsp;Objedls are contained in a larger : as fup-pofe, for Inftance, I dcfire to know, hownbsp;many Animalcules would make up the Big-nefs of a Grain of Sand. To anfwer this,nbsp;the Cube as well as the Superficies of thenbsp;Animalcules muft be taken into the Account �, as will be (hewn in the next Chapter.

As this Treatife is chiefly intended for thofe who underltand but little of fuch Matters, it may neither be needlefs nor unacceptable, to give a Table of the magnifyingnbsp;Powers of the convex Glaffes commonlynbsp;ufed in Angle Microfcopes, according tonbsp;their different Focus : whereby, upon mea-furing whdt the bed Didance from thenbsp;Glafs to vievv the Objcdt is, its Power ofnbsp;magnifying the Diameter, the Superficies,nbsp;and the Cube of an Objedl, will be foundnbsp;in one Line.

D 7 nbsp;nbsp;nbsp;See

As this Table is given in round Numbers, it is fo clear and eafy, that I believe whoever can but divide and multiply a fewnbsp;Figures will readily underftand it.

I have taken no Notice of any Magniher �w'�hofe Focus is at a greater Diftance thannbsp;the half of an Inch ; becaufe Glaifes thatnbsp;magnify lefs than that, may very eafily benbsp;calculated by the Rules above laid down :nbsp;nor, when I come to the greatcft Magnifiers,nbsp;have I mentioned any of a thorter Focusnbsp;than the one hundreth Part of an Inch jnbsp;fince it is fo difficult to grind a Lens to anbsp;Smallnefs beyotjd, or even fo minute as this,nbsp;that perhaps few of my Readers may evernbsp;meet with fuch an one. And though Globules of Glafs may be melted fo extremelynbsp;little as to have their Focus at not half thisnbsp;Diftance, and confequently their magnifyingnbsp;Powers prodigiouflygreaterj theUfeof themnbsp;is fo troublefome, and attended with fuchnbsp;Want of Light, fuch Undiftin�nefs andnbsp;Uncertainty, that, indeed, they are of verynbsp;little Service.

The magnifying Powers of theGlafles employed in Wilson�s nbsp;nbsp;nbsp;Microfcope, and

alfo of thofe belongmg to the opake Microfcope, are to be calculated in the foregoing Manner. And as People will, no Doubt,

Ito he placed after Page 36.

� A TABLE of the MAGNIFYING POWERS of CONVEX GLASSES, employed in Single Microscopes, according to the Diftance of theirnbsp;Focus : Calculated by the Scale of an Inch divided into an Hundred Parts :

Shewing how many Times the Diameter, the Superficies, and the Cube of an Objedt is magnified, when viewed through fuch Glajfes, to an Eye whofe natural Sight is atnbsp;Eight Inches, or Eight Hundred of the Hundredth Parts of an Inch.

J The greateft Magnifier in Mr. Leeuwenhoek�s Cabinet of Microfcopes, prefented to the Royal Society, has its Focus, as nearly as can well be meafuied, at one Twentieth of an Inch Dillance from its Center, andnbsp;confequently magnifies the Diameter of an Objedl 160 Times, and the Superficies 25,600. Bat the greateftnbsp;Magnifier in Mr. Wilson's Single Microfcopes, as they are now made, has ufually its Focus at no farthernbsp;Ditlance than about the Fiftieth Part of an Inch ; whereby it has the Power of enlarging the Diameter ofnbsp;an Objefl 400, and its Superficies 160,000 Times.

be pleafed to know certainly what the Powers of their Glaffes are, and confequentl^ what may be expedled from them, it wouldnbsp;be much better if the Microfcope-Makersnbsp;would grind their GlalTes according to fomenbsp;fettled Standard, and not work by Guefs, asnbsp;they ufually do at prefent, whereby no twonbsp;Sets of Magnifiers can be fuppofed exactlynbsp;alike. Such a Standard, which would affordnbsp;a very ufeful Set of Glaifes, magnifying onenbsp;more than another in due Degrees, is, Inbsp;think, as follows.

T:he FOCAL DISTANCES of Six Magnifiers for Mr. Wilson�snbsp;Pocket Microfcope.

The FOCAL DISTANCES of Four Magnifiers for the Microfcopenbsp;for Opake Objedls.

The magnifying Power of the Solar Microfcope muft be calculated in fomewhat a dififerent Manner. For here the Differencenbsp;between the Focus of the Magnifier, andnbsp;the Diftance of the Screen or Sheet whereon the Image of an Objedl is caft, is the Proportion of its being magnified Suppofe, fornbsp;Infiance, the Lens made ufe of has its Focusnbsp;at half an Inch, and the Screen be placednbsp;at the Diftance of five Feet j the Objedtnbsp;will then appear enlarged in the Proportionnbsp;of five Feet to half an Inch ; and as in fivenbsp;Feet there are one hundred and twenty halfnbsp;Inches, the Diameter will be magnified onenbsp;hundred and twenty Times ; which, multiplied by one hundred and twenty, fliews thenbsp;Superficies to be magnified fourteen thou-fand and four hundred Times: and by put-

ting the Screen at further Diftances, you may magnify your Obje�t to almoft whatnbsp;Size you pleile. But I would advife allnbsp;who ufe this Sort of Microfcope, to regardnbsp;Diftindlnefs more than Bignefs, and placenbsp;the Screen juft at that Diftance where thenbsp;Objedl is feen moft fliarp and clear.

I Should now ftiew the Method of computing the magnifying Power of our Double Microfcope, as I have done of thenbsp;Single ones : but a Calculation of the Powersnbsp;of three combined Glaftes would appear fonbsp;intricate and unintelligible to People unacquainted with Optics (for whofe Servicenbsp;chiefly I intend this Treatife) that I believenbsp;they will readily excufe my perplexing themnbsp;with it: and as for the Learned in that Science, they probably will be better pleafednbsp;to calculate for themfelves.

The Double refledling Microfcope, defcri-bed p, 16. is the only Inftrument at prefent made amongft us for this Purpofe, whereinnbsp;fuch a Combination of Glaftes is employed.nbsp;Here, indeed, the magnifying Power of the

Objedt-Lens is greatly increafed by the Addition of two Eye-Glaffes; but as noObjedt-Lens can be ufed with them of fo minute a Diameter, or that magnifies of itfelf near fonbsp;much ag the Lenfes we can ufe alone, uponnbsp;the whole, the Glafles of this Double Micro-fcope magnify little or nothing more thannbsp;thofe of Mr. Wilson�s Single one. Andnbsp;the fame Table which Ihews the Powers ofnbsp;the Glaffes belonging to that Microfcope,nbsp;may ferve for thefe alfo. For the frji Glafs^nbsp;fecond Glafs, amp;c. of either Microfcope, magnify pretty much alike; and the chief Advantage arifing from a Combination of Glaffes is, the Sight of a large Field or Portionnbsp;of an Objedt, magnified in the fame Degree.

TH 0� by the preceding Diredfcions the magnifying Powers of Microfcope^nbsp;Glaffes may eafily be underftood, it will ilillnbsp;remain uncertain (if the Objedls we examinenbsp;are exceedingly minute) what the real Big-nefs of them is. For though we may knownbsp;they are magnified fo many thoufand Times,nbsp;we can make by that Knowledge but a verynbsp;imperfedl Computation of their natural and,

truQ

true Size ; nor can we, indeed, come to any certain Conclufion as to that, but by thenbsp;Mediation of fome larger Obje�l, whofenbsp;Dimenfions we really know. For as Bulknbsp;itfelf is merely comparative, the only Waynbsp;we can judge of the Bignefs of any thing is,nbsp;by comparing it with fomething elfe, andnbsp;finding out how many Times the lelTer isnbsp;contained in the larger Body. To do thisnbsp;in Microfcopical Objedls, feveral ingeniousnbsp;Methods have been contrived; of which,nbsp;fuch as are come to my Knowledge, and arenbsp;plain and pra�ticable, I fhall lay before thenbsp;Reader.

Mr. Leeuwenhoek�s Way of computing the Size of Salts in Fluids, of the Animalcules in Semine Mafeulino, in Pepper-Water, tcc. was, by comparing them with the Bignefs of a Grain of Sand ¹} and hisnbsp;Calculations were made in the followingnbsp;Manner.

N. B. It is proper to inform the Reader, that where-ever, in this Treatife, Microfcopical Objefts are compared with a Grain of Sand, which commonly was the Meafurenbsp;Mr. Leeuwenhoek made ufe of, we muft underftand it tonbsp;mean a Grain of coarfe Sea-Sand (ufually called Scouring-Sand) which is equal in Bignefs to feveral Grains of ournbsp;common Inland Hmfe-Sand, or Writing-Sand. But to makenbsp;our Calculation ftill more certain, we muft fuppofe them ofnbsp;fuch a Size, that an hundred of them placed in a Row lhallnbsp;extend an Inch in Length.

He viewed through his Microfcopc a Angle Grain of Sand which we will fuppofe to be rr-agnified as the round Figure ABCD.nbsp;Then obferving the Animalcule fwirnmirg,nbsp;or running acrofs it, or coming near it,nbsp;(which we will imagine to be of the Size i.)nbsp;conhdering and meafuring this by his Eye,nbsp;he concludes, that the Diameter of thisnbsp;Animalcule is lefs by a twelfth Part thannbsp;the Diameter of the Grain of Sand ; confe-quently, according to the common Rules,nbsp;the Superficies of the Grain of Sand is onenbsp;hundred forty-four Times, and the wholenbsp;Contents thereof one thoufand feven hundred and twenty-eight Times, larger thannbsp;this Apimalcule.

Suppofe, again, that he fees among thefe another and fmaller Species of Animalcules \nbsp;one of which [2.] he like wife meafures withnbsp;his Eye, by the Help of a good Microfeope ;nbsp;and computes its Diameter to be five Times,nbsp;but, to be within Compafs, he reckons itnbsp;only four Times lefs than the former Animalcule I. According then to the foregoing Rules, the Diameter of this will be fix-teen, and the whole Bulk fixty-four Timesnbsp;lefs than the Animalcule i.

If farther, upon a nicer View, he difeo-vers a third Sort of Animalcule [3.] fo ex-

ceedingly minute that, examining it in the former Manner, he concludes that the Diameter thereof is ten Times fmaller than thenbsp;fecond Sort: it will then follow, that anbsp;thoufand of thefe are but equal in Bignefsnbsp;to one of that fecond Sort.

The firft Sort multiplied by the fecond, and the fecond by the third, will plainly de-monftrate how many of this third and minuted; Sort are requifite to make up thenbsp;Bulk of a Angle Grain of Sand : the Procefsnbsp;of which is as follows.

Third Sort, 3. whofe Diameter is lefs thaa that of the fecond Sortnbsp;10 Times.

After this Manner the comparative Size of all Sorts,of Objects may very eafily benbsp;computed, only fubftituting (for fuch as arenbsp;lefs minute) a fmall Seed, or fome othernbsp;Body whofe Size we are well acquaintednbsp;with, in the room of a Grain of Sand.nbsp;And, particularly, by the Solar Microfeope,nbsp;our Calculations may be made with greatnbsp;Certainty; fince the Image of the Objedt

enquired after, and of the Grain of Sand, the fmall Seed, or whatever elfe is thoughtnbsp;proper to compare with it, may be reallynbsp;meafured by a Ruler, or a Pair of Compaffes,nbsp;and the Difference of their Diameters moftnbsp;exadlly found.

The Method Mr. Hooke made ufe of, to know how much an Obje�t appears magnified, I {hall give in his own Words.�*nbsp;Having (fays he) rectified the Microfcope,nbsp;to fee the defired Obje61: through it verynbsp;** diftindlly; at the fame time that I looknbsp;upon the Obje�t through the Glafs withnbsp;� one Eye, I look upon other Objedls atnbsp;the fame Diftance with my other barenbsp;Eye : by which means I am able, by thenbsp;Help of a Ruler, divided into Inches andnbsp;fmall Parts, and laid on the Pedeflal ofnbsp;the Microfcope, to caff, as it were, thenbsp;� magnified Appearance of the Objecft uponnbsp;the Ruler, and thereby exadfly to mea-fure the Diameter it appears of throughnbsp;� the Glafs j which being compared withnbsp;� the Diameter it appears of to the nakednbsp;Eye, will eafily afford the Quantity of itsnbsp;� being magnified.��This, for Multitudesnbsp;of Objedls, is a ready and good Way} andnbsp;I can declare, from my own Experience, thatnbsp;a little Pradlice will render it exceeding eafynbsp;and pleafant.

Another very curious Way for this Pur-pofe is defcribedby the ingenious Dr. Jukin,

in the 45th Page of his Phyjico-Mathematical Dijfertations; the Manner whereof is thus :nbsp;Wind a Piece of the fineft Silver Wire younbsp;can get a great many Times about a Pin, ornbsp;fome other fuch flender Body, fo clofely asnbsp;to leave no Interval between the Wire-Threads ; to be certain of which, they mull;nbsp;be carefully examined with a Glafs. Then,nbsp;with the Points of a fmall Pair of Compaffes,nbsp;meafure exaftly what Length of Pin thenbsp;Wire covers: and applying the Compaffesnbsp;with that Meafure to a diagonal Scale ofnbsp;Inches, you will find how much it is; afternbsp;which, by counting the Number of Wire-Rounds contained in that Length, you willnbsp;eafily difcover the real Thicknefs of the fin-gle Wire. This being known, cut it intonbsp;very fmall Pieces, and when you examine annbsp;Objedt, if it be opake, ftrew fome of thefenbsp;Wires upon it j if tranfparent, under it; andnbsp;with your Eye compare the Parts of thenbsp;Objedt with the Thicknefs of fuch Bits ofnbsp;Wire as lie faireff to your View.

By this Method Dr. Jurin obferved, that four Globules of human Blood would generally cover the Breadth of a Wire, which henbsp;had found to be th Part of an Inch ; andnbsp;confequently, that the Diameter of a finglenbsp;Globule was -�Vs^th Part of an Inch. Whichnbsp;was alfo confirmed by Mr. Leeuwenhoe k�s Obfervations upon human Blood,nbsp;made with a Piece of the fame Wire, fent

Mr. Martin, in his Optics, gives another Way, fufficiently eafy and ready on all Occafions. On a circular Piece of Glafs,nbsp;let a Number of parallel Lines be drawnnbsp;carefully, with the fine Point of a Diamond,nbsp;at the Diftance of one fortieth Part of annbsp;Inch from each other. If this be placed innbsp;the Focus of the Eye-glafs of a Microfcope,nbsp;the Image of the Objecft will be feen uponnbsp;thefe Lines, and the Parts thereof may benbsp;compared with the Intervals, whereby itsnbsp;true Magnitude, or Dimenfions, may be verynbsp;nearly known : for the Intervals of thefenbsp;Lines, tho� fcarce difcernible to the nakednbsp;Eye , appear very large through the Microfcope. A Contrivance of this Kind may alfonbsp;be invented for fuch Microfeopes as a Glafsnbsp;cannot be applied to in the above Manner,nbsp;by placing it under or behind the Obje�t,nbsp;which will anfwer the fame Purpdfe.

Here it will be eafy to find what Proportion an Objedl, or any Part thereof, bears to an Interval between two Lines, and thennbsp;determine it in Parts of an Inch : for if thenbsp;Width of an Objedb appears juft one Interval, we fhall know it to be juft one fortiethnbsp;Part of an Inch; if half an Interval, thenbsp;eightieth; if a Quarter of an Interval, thenbsp;one hundred and fixtieth j if one fifth, onlynbsp;the two hundredth Part of an Inch.

Dr. Smith has an Invention akin to this, for taking exad: Draughts of Objects, viewed in Double Microfcopes ; for he advifesnbsp;to get a Lattice made with fmall Silvernbsp;Wires, or fmall Squares drawn upon a plainnbsp;Glafs by the Strokes of a Diamond, and tonbsp;put it into the Place of the Image formednbsp;by the Objedl-Glafs. Then, by transferringnbsp;the Parts of the Objedl feen in the Squaresnbsp;of the Glafs or Lattice upon fimilar corre-fponding Squares drawn on Paper, the Picture thereof may be exadtly taken.

There are fome other Sorts of Micrometers, or Inventions for mealuring the fmall Objedls feen in Microfcopes �, but as they arenbsp;more complex and difficult, I ffiall not fwellnbsp;this Volume with them.

H E vifible Area, Field of View, or I Portion of any Objeft feen through anbsp;Microfcope, is in Proportion to the Diameternbsp;and Area of the Lens made ufe of, and itsnbsp;Power of magnifying, and may be therebynbsp;determined : lince, if the Lens is extremelynbsp;fmall, it magnifies a great deal, and, con-fequently, a very minute Portion only of an

Objedl can be diftinguiflied through it. For which Reafon the greateft Magnifiers nevernbsp;ihould be employed but for the rnofh minute

how to fuit the Magnifiers to the Size of the Objefts to be examined, which is of thenbsp;utmoft Confequence in Microfcopical Ob-fervations j and may ferve to re�lify thenbsp;Miftake of Abundance of People unexperienced in Glaifes, who, upon feeing a Mitenbsp;or a Loufe greatly magnified, are apt to crynbsp;out with much Surprize, O that we had anbsp;Cricket, a Frog, or fome other Creature;nbsp;how finely that would appear ! Whereas, innbsp;truth, fuch large Objedls would entirely covernbsp;the Lens, and could not be feen at all.

Microfeopes very happily affifl; us when Objedls are fo fmall as to evade our Sight;nbsp;but it would be trifling and unneceflfary tonbsp;employ them on fuch large Things as we cannbsp;fee without their Help.

I {hall not trouble the Unlkilful with perplexing Calculations about the Area ornbsp;Field of Objefts feen by each Magnifier ;nbsp;but give this fhort Rule in general, that itnbsp;differs not greatly from the Size of the Lensnbsp;made ufe of, and that the Whole of any Ob-jedt, much beyond that Size, cannot conveniently be viewed through it.

There is fome Difference, as to the vifiblc Areaof an Objedt, between Single and Doublenbsp;Microfeopes; for the Double fhew a larger

Having fhewn the Strufture and Powers of Microfcopes, I proceed now to defcribenbsp;the Manner of chufing, preparing, and applying Objedls to them.

PRoper Objedls to be examined by Microfcopes are (as Mr. Hooke very ju-dicioufly difiinguiihes) � exceedmg fmall Bo~ � dies, exceeding fmall Pores, or exceedingnbsp;� fmall Motions.�

Exceeding fmall Bodies mufi: either be the Parts of larger Bodies, or Things thenbsp;Whole whereof is exceedingly minute ;nbsp;fuch as fmall Seeds, Infedts, Sands, Salts,nbsp;efc.

Exceeding fmall Pores' are the Interftices between the folid Parts of Bodies, as in Stones,nbsp;Minerals, Shells, amp;c. or the Mouths of minute Velfels in Vegetables, the Pores in thenbsp;Skin, Bones, amp;c. of Animals.

ments of the feveral Parts or Members of minute Animals, or the Motion of the Fluids

Under one or other of thefe three Heads almoft every thing around us affords Matternbsp;of Examination, and may conduce both tonbsp;our Amufement and Inftrudion j as I hopenbsp;more particularly to fhew.

Many, even of thofe who have purchafed Microfcopes, are fo little acquainted withnbsp;their general and extenfive Ul'efulnefs, andnbsp;fo much at a Lofs for Objedts to examine bynbsp;them that, after diverting themfelves andnbsp;their Friends, fome few Times, with whatnbsp;they find in the Sliders bought with them,nbsp;or two or three more common Things, thenbsp;Microfcopes are laid afide as of little farthernbsp;Value ; and a Suppofition that this muft benbsp;the Cafe, prevents many others from buyingnbsp;them : whereas, among all the Inventionsnbsp;that ever appeared in the World, none cannbsp;iperhaps be found fo conftantly capable ofnbsp;entertaining, improving, and Satisfying thenbsp;Mind of Man.�To evince this, and excitenbsp;thofe whofeTime and Circumftances permit,nbsp;to this delightful Study, is the Intention ofnbsp;my writing ; and as Curiofity, the univerfalnbsp;Paflion of Mankind, may this Way continually be gratified, I hope I fhall not write innbsp;vam. And if I can hereby induce any tonbsp;pafs thofe leifure Hours agreeably and ufe-fully in contemplating the Wonders of thenbsp;, E 3nbsp;nbsp;nbsp;nbsp;Creation,

Creation, which otherwife would be fpent in tirefome Idlenefs, or, perhaps, fome fa-fhionable and expenlive Vice, I fhall think;nbsp;thefe Sheets very happily beflowed.

CHAP. XIII.

An Examination of Objects, in order to difcover Truth, requires a great dealnbsp;of Attention, Care, and Patience, togethernbsp;with fome confiderable Skill and Dexteritynbsp;(to be acquired by Pra�lice chiefly) in thenbsp;preparing, managing, and applying them tonbsp;the Microfcope. What little Knowledgenbsp;in thefe Matters I may have gained, eithernbsp;from the Accounts of others, or my ownnbsp;Experience, after being converfant manynbsp;Years therein, I ihall readily communicate:nbsp;in hopes my Pains may clear the Way tonbsp;Difcoveries that will prove of Confequencenbsp;to the World, and render this Study bothnbsp;defirable and eafy.

When any Objedl comes to be examined, the Size, the Contexture, and Nature of itnbsp;fliould be duly confidered; in order to applynbsp;it to fuch GlaflTes, and in fuch a Manner, asnbsp;may Ihew it beft. The firft Step towardsnbsp;this conftantly fliould be, to view it through

a Magnifier that can take in the Whole at once : for by obferving how the Parts lie asnbsp;to one another, we {hall find it much eafiernbsp;to examine and judge of them feparately, if

ourfelves acquainted with the Form of the Whole, we may divide it as we pleafe, andnbsp;the fmaller the Parts into which it is divided,nbsp;the greater muft be the Magnifiers wherewith to view them.

The Tranfparency or Opakenefs of an Objedt muff alfo be well regarded, and thenbsp;Glalfes made ufe of muft be accordinglynbsp;fuited thereto j for a tranfparent Objedt willnbsp;bear a much greater Magnifier than one thatnbsp;is opake; fince the Nearnefs a Glafs thatnbsp;magnifies much muft be placed at, unavoidably darkens an opake �bjedl, and prevents its being feen, unlefs by the Micro-fcope on purpofe for fuch Subjects, defcribednbsp;page 27. Moft Objedts, however, becomenbsp;tranfparent by being divided into extremelynbsp;thin or minute Parts. Contrivance therefore is neceflary, to reduce them into fuchnbsp;Thinnefs or Smallnefs as may render themnbsp;moft fit for Examination.

The Nature of the Objedl, whether it be alive or dead, a Solid or a Fluid, an Animal, a Vegetable, or a Mineral Subftance,nbsp;muft likewife be confidered, and all thenbsp;Circumftances of it attended to, th it we maynbsp;apply it in the moft convenient Manner. If

E 4 nbsp;nbsp;nbsp;it

it be a living Animal, Care muft be taken to fqueeze, hurt, or difcompofe it as little asnbsp;poffible, that its right Form, Pollute, andnbsp;Temper may be difcovered. If a Fluid, andnbsp;too thick, it mull be thinned with Water:nbsp;if too thin, we fhould let fome of its waterynbsp;Parts evaporate. Some Subftances are fitteflnbsp;for Obfervation when dry, others again whennbsp;moiflened ; fome when frefh, and fome afternbsp;being kept a while.

Light is the next thing to be taken care of, for on this the Truth of all our Examination depends �, and a very little Experiencenbsp;will hiew how different Objedls appear innbsp;one Pofition and Kind of it, to what theynbsp;do in another. So that we Ihould turn themnbsp;every Way, and view them in every Degreenbsp;of Light, from Brightnefs even to Obfcurity,nbsp;and in all Pofitions to each Degree; till wenbsp;are certain of their true Form, and that wenbsp;are not deceived. For, as Mr. Hookenbsp;fays, in many Objedts it is very difficult tonbsp;diftinguiffi between a Prominency and anbsp;Depreffion j between a Shadow and a blacknbsp;Stain ; and in Colour, between a Refledlionnbsp;and a Whitenefs. The Eye of a Fly, fornbsp;Example, in one Kind of Light, appears likenbsp;a Lattice drilled through with Abundancenbsp;of Holes ; in the Sun-lhine, like a Surfacenbsp;covered with golden Nails : in one Pofition,nbsp;like a Surface covered with Pyramids ; in

The Degree of Light muft be duly fuit-ed to the Objeft; which, if dark, will be feen beft in a full and ftrong Light; but ifnbsp;very tranfparent, the Light fhould be pro-portionably weak : for which Reafon therenbsp;is a Contrivance, both in the Single andnbsp;Double Microfcope, to cut off Abundance ofnbsp;its Rays, when fuch tranfparent Objefts arenbsp;examined by the greateft Magnifiers.

The Light of a Candle, for many Objedls, and efpecially fuch as are exceedingly minutenbsp;and tranfparent, is preferable to Day-light:nbsp;and for others Day-light is beft ; I mean thenbsp;Light of a bright Cloud. As for Sun-ftiine,nbsp;it is refledled from Objedls with fo muchnbsp;Glare, and exhibits fuch gaudy Colours,nbsp;that nothing can be determined by it withnbsp;Certainty j and therefore it is to be accountednbsp;the worft Light that can be had.

This Opinion of Sun-ftiine muft not however be extended to the Solar Microfcope, which cannot be ufed to Advantagenbsp;without its brighteft Light ; for in thatnbsp;Way we fee not the Objedl itfelf whereonnbsp;the Sun-lhine is caft, but only the Image ornbsp;Shadow of it exhibited upon a Screen and,nbsp;therefore, no Confufion can arife by thenbsp;glaring Refle�lion of the Sun�s Rays from,nbsp;the Obje�t to the Eye, which is the Cafe innbsp;other Microfeopes. But then, in that Solar

Way, we muft reft contented with viewing the true Form and Shape of an Objed;, without expeding to find its natural Colour,nbsp;fince no Shadow can pofiibly wear the Colours of the Body it reprefents.

Most Objeds require fome Management, in order to bring them properly before the Glaffes.�If they are flat and tranfparent, and fuch as will not be injurednbsp;by PrelTure, the beft Method is to inclofenbsp;them in Sliders, between two Mufcovy Talcsnbsp;or Ifinglafs. This Way the Feathers ofnbsp;Butterflies, the Scales of Fufties, the Farinaenbsp;of Flowers, amp;c. the feveral Parts, and evennbsp;whole Bodies of minute Infeds, and anbsp;thoufand other Things, may very conveniently be preferved. Every curious Obfervernbsp;will therefore have them always ready tonbsp;receive any accidental Objed, and fecure itnbsp;for future Examination ; and a Dozen ornbsp;two of thefe Sliders, judicioufly furnifhed,nbsp;are a fine natural Eliftory, where we maynbsp;read delightful Leflbns of the high Perfection of God�s Worjes, and his Wifdom innbsp;their Contrivance.

In making a Colledion of Objeds, the Sliders fliould not b? filled promifeuoufly,

but Care taken to fort the Objefts according to their Size and Tranfparency ; in fuchnbsp;Manner that none be put together in thenbsp;fame Slider, but what may properly be ex- ,nbsp;amined by the fame Magnifier : and thennbsp;the Slider fhould be marked with the Number of the Magnifier its Obje�ls are fitted:nbsp;for; that is, the mod: tranfparent, or minuted Objedls of all, which require the firftnbsp;Magnifier to view them by, diould be placed in a Slider, or Sliders, marked with Number 1.; thofe of the next Degree in Slidersnbsp;marked with Number II. and fo of the red.nbsp;This Method will fave Abundance of Timenbsp;and Trouble in ihifting the Magnifiers,nbsp;which, without fuch Sortment, mud perhapsnbsp;be done two or three Times in overlookingnbsp;a fingle Slider ¹. The Numbers inarkednbsp;upon the Sliders will likewife prevent our being at any Lofs what Glafs to apply to each.

Small living Objeds, fuch as Lice, Fleas, Gnats, fmall Bugs, minute Spiders, Mites,nbsp;Gfc. may be placed within thefe Talcsnbsp;without killing or hurting them, if Care benbsp;taken not to prefs down the Brafs Ringsnbsp;that keep in the Talcs; and will remain

In placing your Objefts in Sliders, a convex Glafs of about an Inch Focus, to hold in the Hand, and therebynbsp;adjuft them properly between the Talcs, before you faftennbsp;them down with the Brafs Rings, will be found very convenient.

live even Weeks in this Manner. But if they are larger than to be treated thus, eithernbsp;put them in a Slider with concave Glaffes,nbsp;intended for that Ufe, and defcribed pagenbsp;lo. or in the Cell, page 19. or elfe examinenbsp;them fluck on the Pin, or held between thenbsp;Flyers ; either of which Ways they maybenbsp;viewed at Pleafure.

If Fluids come under Examination, to difcover the Animalcules that may be innbsp;them, take up a fmall Drop with your Pen,nbsp;or Hair-pencil, and place it on a fingle Ifm-glafs (which you fliould have in a Slidernbsp;ready) or elfe in one of the little concavenbsp;Glaffes, and fo apply it. But in cafe, uponnbsp;viewing it, you find, as often happens, thenbsp;Animalcules fwarming together', and fo exceedingly numerous, that, running continually over one another, their Kinds and realnbsp;Form cannot be known ; fome Part of thenbsp;Drop muff be taken off the Glafs, and thennbsp;a little fair Water put to the reft will makenbsp;them feparate, and ftiew them diftindt andnbsp;well. And this Mixture of Water is particularly requifite in viewing the Semen Maf~nbsp;culinum of all Creatures: for the Animalcules therein contained are unconceivablynbsp;minute, and yet crowded together in fuchnbsp;infinite Numbers, that unlefs it be diluted anbsp;great deal, they cannot be fufficiently fepa-rated to diftinguifh their true Shape.

But, if we view a Fluid to find what Salts it may have in it, a Method quite contrary to the foregoing muft be employed :nbsp;for then the Fluid mufi; be fuffered to evaporate, that the Salts, being left behind uponnbsp;the Glafs, may more eafily be examined. '

Another, and indeed the mofi: curious Way of examining Fluids, is, by applyingnbsp;them to the Microfcope in exceedingly fmallnbsp;capillary Tubes, made of the thinned; Glafsnbsp;poffible. This was Mr. Leeuwenhoek�snbsp;Method for difcovering the Shapes of Saltsnbsp;floating in Vinegar, Wine, and feveral othernbsp;Liquors ; and fuch Tubes lliould be alwaysnbsp;ready to ufe as Occafion requires.

For the Circulation of the Blood, Frogs, Newts, or Fifhes, are commonly made ufenbsp;of: and there are Glafs Tubes in the Singlenbsp;Microfcope, and aFifh-pan, as well as Tubes,nbsp;in the Double one, on purpofe to confinenbsp;thefe Creatures, and bring the proper Partsnbsp;of them to View : which, in Newts andnbsp;F'iihes, are the Tails, and in Frogs the finenbsp;filmy Membrane between the Toes of thenbsp;hinder Legs. Though, if we can contrivenbsp;to fallen down the Creature, and bring ournbsp;Objedl to the Magnifier, the Circulation cannot poffibly be feen fo plainly any where asnbsp;in the Mefentery, or thin tranfparent Membrane that joins the Guts together; and thisnbsp;Part, by pulling out the Gut a little, maynbsp;eafily be adjufted to the Magnifier.

To diffedl minute Infefts, as Fleas, Lice, Gnats, Mites, amp;c. and view their internalnbsp;Strudlure, requires a great deal of Patiencenbsp;and Dexterity : yet even this may be donenbsp;in a very fatisfadtory Manner, by means ofnbsp;a fine Lancet and Needle, if they are placednbsp;in a Drop of Water : for their Parts willnbsp;then be feparated with Eafe, and lie fair before theMicrofcope, fo that the Stomach andnbsp;other Bowels may plainly be diftinguithednbsp;and examined.

We fhould always have ready for this Purpofe little Slips of Glafs, about the Big-nefs of a Slider, to place Objedts on oc-cafionally ; fome of which Slips tliould benbsp;made of green, blue, and other different coloured Glafs ; many Objedts being muchnbsp;more diftinguifhable when placed on onenbsp;Colour than on another. We fhould like-wife be provided with Glafs-Tubes of allnbsp;Sizes, from the fineft Capillaries that can benbsp;blown, to a Bore of half an Inch Diameter.

I believe there is no better Way of pre-ferving tranfparent Objedts in general, than by placing them between clear Ifmglafs innbsp;Sliders : but opake Bodies, fuch as Seeds,nbsp;Sands, Woods, ֒c. require different Management j and a Colleftion of them fhouldnbsp;be prepared in the following Manner.

Cut Cards into fmall Slips, about half an Inch in Length, and the tenth of an Inchnbsp;broad : wet them half their Length with a

ftrong but very tranfparent Gum-water, and with that flick on your Objegt;fl. As the Spotsnbsp;of Cards are red and black, by making yournbsp;Slips of fuch Spots, you will obtain a Contrailnbsp;to Objedls of alrnoft any Colour; and bynbsp;fixing black Things on the white, white onnbsp;the black, blue or green on the red or white,nbsp;and all other coloured Obje�ls on Slips moftnbsp;contrary to themfelves, they will be, fhewnnbsp;to the befl Advantage. Thefe Slips are intended chiefly for the new-invented Micro-fcope for opake Objedls, to be applied between the Nippers: but they will alfo be proper for any other Microfcope that can fhewnbsp;opake Bodies. A little fquare Box fhould benbsp;contrived to keep thefe Slips in, with a Number of very fliallow Holes juft big enoughnbsp;to hold them. If fuch Holes were cutnbsp;through Pieces of that Pafleboard Covers ofnbsp;Books are made of, exactly fitted to the Box,nbsp;and a Paper was pafled on one Side of eachnbsp;to ferve for a Bottom to it, three or fournbsp;fuch Pafleboards, flored with Objects, mightnbsp;lie one upon another in the fame Box, andnbsp;contain an hundred or more Slips, with Ob-jedls faflened on them, always ready for Examination. It will not be found amifs tonbsp;provide forne Slips larger than others, fornbsp;the Reception of different-fized Obje�ls :nbsp;but the Pattern hereto annexed f Plate VI.)nbsp;will better explain my Meaning. The Boxnbsp;fhould likewife be furniflied with a Pair of

PJyers, to take up and adj�uft the Slips ; and therefore a convenient Place is contrivednbsp;therein to hold them, as the Plate beforenbsp;you fhews

Beware of determining and declaring your Opinion fuddenly on any Objedl;nbsp;for Imagination often gets the Start of Judgment, and makes People believe they feenbsp;Things, which better Obfervations will convince them could not poffibly be feen; therefore alTert nothing till after repeated Experiments and Examinations, in all Lights, andnbsp;in all Pofitions.

When you employ the Microfcope, fhake off all Prejudice, nor harbour any favouritenbsp;Opinions j for, if you do, it is not unlikelynbsp;Fancy will betray you into Error, and makenbsp;you think you fee what you would wiflh to fee.

Remember, that Truth alone is the Matter you are in Search after and if you have been miftaken, let no Vanity feduce you tonbsp;perfift in your Miftake.

* Mr. Cuff, in Fleet-Jireet, can fupply thofe who do not care to give themfelves the Trouble of making them, withnbsp;Boxes after this Pattern, which are found by Experience to benbsp;extremely ufeful: He likewife makes and fells all the Micro-/copes, with their Apparatus, mentioned in this Treatife-

Pafs no Judgment upon Things over-extended by Force, or contracfled by Drynefs, or in any Manner out of their natural State,nbsp;without making fuitable Allowances.

There is no Advantage in examining any Objeft with a greater Magnifier than whatnbsp;fliews the fame diflinftly; and therefore, ifnbsp;you can fee it well with the third or fourthnbsp;Glafs, never ufe the firfl; or fecond �, for thenbsp;iefs a Glafs magnifies, the better Light younbsp;will have, the eafier you can manage thenbsp;Object, and the clearer it will appear.

It is much to be doubted, whether the true Colours of Ohjefts are to be Judged of,nbsp;when feen through the greatefi: Magnifiers :nbsp;for as the Pores or Interfiices of an Objectnbsp;mufi: be enlarged according to the magnifying Power of the Glafs made ufe of, and thenbsp;component Particles of Matter muft by thenbsp;fame Means appear feparated many thou-fands of times farther afunder than they donbsp;to the naked Eye, their Reflexions of thenbsp;Rays of Light will probably be dilferent, andnbsp;.exhibit different Colours. And indeed thenbsp;Variety of Colouring fome ObjeXs appearnbsp;dreft in, may fervc as a Proof of this.

The Motions of living Creatures them-felves, or of the Fluids contained within them, as feen through the Microfcope, arenbsp;likewife not to be determined without duenbsp;Confideration : for as the moving body andnbsp;fhe Space wherein it moves are magnified,

VoL. J. nbsp;nbsp;nbsp;Fnbsp;nbsp;nbsp;nbsp;the

the Motion muft probably be fo too. And therefore that Pvapidity, wherewith theBloodnbsp;feems to pafs along through the Velfels ofnbsp;fmall Animals, mufl; be judged of accordingly. Suppofe, for Inftance, a Horfe and anbsp;Moufe move their Limbs exactly at the famenbsp;Moment of Time : if the Plorfe runs a Milenbsp;while the Moufe runs fifty Yards (thoughnbsp;the Number of Steps are in both the fame)nbsp;we fliall readily, I believe, allow the Horfe�snbsp;Motion to be fwiftefl. The Motion of anbsp;Mite viewed though a Microfcope, or fcennbsp;by the naked Eye, is, perhaps, not muchnbsp;lefs different.

Some People have made falfe Pretences, and ridiculous Boafls, of feeing, by theirnbsp;Glaffes, the Atoms of Epicurus, the fubtilenbsp;Matter of Dt;s Cartes, the EfHuvia * ofnbsp;Bodies, the Emanations from the Stars, andnbsp;other fuch like Impoflibilities: But let nonbsp;ingenious and honeit Obferver give Credit tonbsp;thefe romantic Stories, or mif-fpend his Timenbsp;and bewilder his Brains in following fuchnbsp;idle Imaginations, when there lies beforenbsp;him an Infinity of real Obje�ls, that may benbsp;examined with Eafe, Profit, and Delight.

� Dr. Highmore pretends that the Effluvia of tlie Load-fione have been feen by Glafies, iffuing from it in the Form of a Mift : and all the reft of the above Extravagances havenbsp;been boafted of by others. Vid. Leeuwen. Art. Nat. Tom. ii.nbsp;P^g- 3 8.

The

MICROSCOPE;

A great Variety of new Experiments and Observations, pointing out many uncommonnbsp;Subjeiis to the Enquiry of the Curious.

PART II.

r 67 1

* nbsp;nbsp;nbsp;lt;lgt;nbsp;nbsp;nbsp;nbsp;?nbsp;nbsp;nbsp;nbsp;?nbsp;nbsp;nbsp;nbsp;4gt;nbsp;nbsp;nbsp;nbsp;?nbsp;nbsp;nbsp;nbsp;lt;gt;

MICROSCOPE

PART 11.

AVING defcribed the mofl uf�* ^ � % ful Kinds of Microscopes mad�nbsp;^nbsp;nbsp;nbsp;nbsp;^ amongft us j fhewn how to cal*

jd culate the magnifying Powers of Glasses* and the real Size ofnbsp;Objects j taught the Ways of preparing^nbsp;examining, and preferving Objects ; and,nbsp;given proper Cautions in our judging of whatnbsp;we view: I come now to the Second Partnbsp;of my Defign, which is* to Ihew what fur-^nbsp;prijing Difcoveries have been already madenbsp;by the Microscope, with ufeful ReJleSiionsnbsp;on them j and alfo to fet forth a great Va^nbsp;riety of new Experiments and Obfervdtions,nbsp;pointing out many uncommon Subjebis for thenbsp;Examination of the Curious*

f �8 ]

CHAP. I.

TH E fmalleft living Creatures yet known are the Animalcules in Fluids ;nbsp;whereof many Kinds have been difcoverednbsp;by the Microicope of fuch an exceeding Mi-nutenefs, that a Million of them would notnbsp;equal the Bignefs of a large Grain of Sand;nbsp;and it is probable, there may be numberlefsnbsp;Species of a Size much lefs than thefe. It isnbsp;alfo likely, that there are as many, or evennbsp;more Kinds of thefe Livifihles (if I may ufenbsp;the Term) than of thofe wliofe Size is dif-cernible by the naked Eye. Here, therefore,nbsp;is Abundance of Scope for Enquiry and Admiration, fince every Drop of Water, ornbsp;other Liquor (excepting Oils and Spirits)nbsp;either does already, or, upon Handing ex-pofed a few Days, will appear full o� livingnbsp;Creatures, of various Sizes and Forms. Somenbsp;Kinds of thefe Animalcules feem to be reallynbsp;Filh, and are natural Inhabitants of the Water all their Lives: others live there but oc-calionally, in the Manner of Gnats, which,nbsp;from Eggs dropped by their Parents in thenbsp;Water, become fwimming Animals; butnbsp;after a while fired their fkins, appear in anbsp;Form that bears no Refemblance to what

We may thus account how Water wherein Pepper, Hay, Oats, Wheat, or other vegetable Subjiances are infufed, will foon become full of Life : for thofe minute and invifblenbsp;little Flies, which are every where hoveringnbsp;in the Air^ and feeking Places to depofitnbsp;their Eggs, when a Fluid offers well ftorednbsp;with proper Nourifhment for their futurenbsp;Offspring, may be fuppofed to refort to it innbsp;Swarms, and lay their Eggs there. Thefenbsp;Eggs being foon hatched, the Infant-Broodnbsp;fwim about, and live happily in the Fluid ;nbsp;till, grown to their ffated Size, they, in duenbsp;Time, change their Forms, employ theirnbsp;Wings, and fly away.

The Truth of this I have often experienced ; for, after obferving fome Kinds of Animalcules in feveral Fluids to be grown to a certain Bignefs, on a fudden I have foundnbsp;them all gone away, and only a much fmal-Jer, and confequently a younger Race, of thenbsp;fame Kinds remaining; which alfo, whennbsp;grown to a like Size, have foon after in thenbsp;fame Manner been gone too. Befldes, ifnbsp;the liifufion be covered, though with a Muf-lin or fine Lawn, 1 have cujiftantly founcfnbsp;that few Animalcules will be produced therein ; but upon taking off the Cover, in a fewnbsp;Days it will be full of Life : which feems tonbsp;prove, that the Eggs whence thefe Animal-F 4nbsp;nbsp;nbsp;nbsp;cides

eiiles come, mufi; either be depolited by their own Parents, as I above luppofe, or benbsp;brought along with the Air. And, indeed,nbsp;both thefe Ways may poffibly be : for as thenbsp;Eggs of fuch minute Creatures are lighternbsp;than Air, Millions of them may continually float therein, and, being wafted everynbsp;where indiflerently, may perifh in Placesnbsp;unfuitable to their Nature, but hatch andnbsp;thrive when they happen to be lodged in anbsp;proper Nidus for them. Some People imagine, that the Eggs of thefe little Creaturesnbsp;are lodged in the Pepper, Hay, or whatevernbsp;elfe is put into the Water: but, were it fo,nbsp;'I cannot think a thin Covering of Lawn,nbsp;which does not exclude the finer Part of thenbsp;Air, would prevent their being hatched^ andnbsp;therefore muft conclude it a Pvliftake.

Though Water that Hands at Refl:, and expofed in the open Air, will, after a fewnbsp;Days, have feme Animalcules in it, they willnbsp;be found in no Degree fo numerous as whennbsp;�vegetable Bodies have been fteeped therein jnbsp;for no Creatures feem able to fubfift on merenbsp;V/ater only,- and what little Particles befidesnbsp;may accidentally happen in it, can maintainnbsp;no great Number : but when, by Infulionnbsp;of the above-mentioned Subitances, \�aternbsp;is ftored with their proper P'ood, the Micro-fcope can fliew Myriads of living Creaturesnbsp;in every little Drop.

6 nbsp;nbsp;nbsp;As

As every curious Perfon will be defirous to view thefe Wonders with his own Eyes,nbsp;and communicate them to his Friends, thenbsp;following Directions for making Pepper-Water^ amp;c. to be kept always ready fornbsp;Obfervation, may not perhaps be unacceptable.

CHAP. ir.

PU T common Black Pepper, grofsly bruifed, into an open Veflel, to covernbsp;the Bottom of it about half an Inch innbsp;Thicknefs, and pour thereon Rain or River-Water, till it rifes above the Pepper an Inchnbsp;or thereabouts. Shake or ftir the Water andnbsp;Pepper very well together when frit younbsp;mix them, but afterwards not at all. Ex-pofc your Veffel to the Air uncovered, andnbsp;in a few Days you will perceive a little Pellicle, or Skin, upon the Surface of the Water, reflecting Prifm Colours. This Skin,nbsp;examined by the Microfcope, will be foundnbsp;to contain Millions oiAnimalcules, fcarcedif-cernible at firfl, even by the greateft Magnifier, but continually growing bigger tillnbsp;they come to their full Size. Their Numbers too will every Day increafe exceedingly,

till at length almoft the whole Fluid feems alive ; though in reality they lie chiefly onnbsp;the Surface of the Water, and go not deepnbsp;therein, unlefs frighted or difturbed; butnbsp;when that happens, they will fometimesnbsp;dart down all at once, and not appear againnbsp;for fome time. In warm Weather this Skinnbsp;rifes on the Surface fooner, and you willnbsp;perceive them grow fafter, than in cold :nbsp;though even in the midil of Winter, if thenbsp;Water be not frozen, the Experiment willnbsp;fucceed.

About the Quantity of a Pin�s Head of this Scum, taken up with the Nib of a newnbsp;Pen, or a fmall Hair-Pencil, and applied onnbsp;a Angle Ifinglafs, firft; to the third Magnifier,nbsp;then to the fecond, and then to the firfl:,nbsp;will' fhew feveral Sorts of Animalcules leflernbsp;each than other, and dlifering a great dealnbsp;in Shape as well as Size.

Firji, The largeft Sort of all (reprefented Plate VIL Fig. I.) -f- The Length of thefe isnbsp;about the Diameter of a Hair, and three ornbsp;four Times more than their Breadth. Theirnbsp;Bodies are very thin and tranfparent, butnbsp;that Side which feems the Back is darkernbsp;than the other. They turn themfelves in

Pepper �Water.

the Water often, and fhew both Back and Belly, as i. 2. Their Edges are fringed, asnbsp;it were, with a great Number of exceedingly minute Feet, which are chiefly feen aboutnbsp;the two Extremities : at one End there arenbsp;likewife fome Briftles longer than the Feet,nbsp;refembling a Tail. Their Motion is fwift;nbsp;and by their Turns, Returns, and fuddennbsp;Stops, they feem continually to be huntingnbsp;about for Prey. They can employ theirnbsp;Feet in running as well as fwimming ; fornbsp;upon putting a Hair amongft them, theynbsp;will often creep along it from End to End,nbsp;bending in feveral odd Poflures.

. .

and fometimes more. Fig. II. i. exhibits one of them with the Tail extended. 2. re-prefents another with its Tail in a Screwlike Form, as they appear very frequently.nbsp;Sometimes, when they He ftill, they thruflnbsp;out and pull back again a fringed or bearded Tongue ; and a Current runs conflantlynbsp;towards them, v/hich is caufed, probably,nbsp;by the nimble Motion of fome minute Finsnbsp;or Legs too fine to be difeerned.

thirdly, A Sort about the Size of the lafl, but without Tails, appearing fometimes innbsp;an oval Shape, as Fig. III. i. and fometimesnbsp;a little longer, refembling a Flounder, in thenbsp;Manner of 2. Their little Feet may be feennbsp;9nbsp;nbsp;nbsp;nbsp;plainly

plainly wheli the Water is juft evaporating* for then they move them nimbly. Nownbsp;and then two of them are feen conjoined*nbsp;as 3.

Fourthly, Another Sort appear like dender Worms, about fifty Times as long as broad,nbsp;and whofe Thicknefs is about the one hundredth Part of a Hair. Their Motion isnbsp;equable and flow, waving their Bodies'generally but little in their Progreflion. Theynbsp;fwim with the fame Facility backwards ornbsp;forwards, and being every where of thenbsp;fame Thicknefs, it is difficult to diftinguiflinbsp;which End the Head is placed at. Seenbsp;Fig. IV.

A fifth Sort are fo amazingly fmall, that an hundred of them in a Row would notnbsp;equal the Diameter of a Grain of Sand, and,nbsp;confequently, a Million of them are butnbsp;equal to a Grain of Sand in Bignefs : theirnbsp;Shape is almoft round.

A Jixth Sort are about the Thicknefs of the foregoing, but almoft twice as long ;nbsp;and, befides thefe, there are doubtlcfs othernbsp;Sorts which have not duly been attendednbsp;to.

It is agreeable enough, while thefe little Creatures are before the Microfcope, to ob-ferve the different Effedls feveral Kinds ofnbsp;IVIixtures produce among them. For Example, putting to them the fmalleft Dropnbsp;imaginable of Spirit of Vitriol upon the Point

of a pin, they immediately fpread them-felves, and appear to tumble down dead. DilTolved Salt kills them, but with this Difference, that inftead of becoming flat, as innbsp;the former Cafe, they Ihrink into ovalnbsp;Forms. Tindture of Salt of Tartar throwsnbsp;them into convulfive Motions, after whichnbsp;they foon grow faint and languid, and thennbsp;die^ without any Change of Shape. Inknbsp;kills them as foon as Spirit of Vitriol, butnbsp;feems to contradf them feveral Ways. Frefhnbsp;Blood, Urine, and Spittle, kill them in anbsp;little while.. Sugar diflTolved does the fame;nbsp;but thereby fpm� die flat, and othersnbsp;round

If the Water be permitted to dry away without any Mixture, fome Sorts of thenbsp;Animalcules will burft, but others not: andnbsp;if a frefh Drop of Water be put to them, innbsp;a little while many of them will revive andnbsp;fwim about again,

CHAP,

[ 7^ ]

' A Y, Straw, Grafs, Oats, Wheat, Barley, or any other vegetable Production,nbsp;being infufed in Water, in the Manner ad-vifed before; after fome Days, a Sort ofnbsp;whitilh Scum, or Motherinefs, will appearnbsp;upon the Surface, which, examined by anbsp;Microfeope, will be found to contain inex-preffible Numbers of minute living Creatures, of various Sizes, Forms, and Kinds.

And of thefe fome are the fame exaCtly as were juft now deferibed in Pepper-Water .�nbsp;for it is to be obferved, that certain Kindsnbsp;of thefe Animalcules are met with, univer-fally, in all Waters that have ftood any con-fiderable Time expofed to the open Air.nbsp;The moft general among them is an ovalnbsp;Sort of Animalcule, fomewhat in the Shapenbsp;of an Emmet�s Egg (See Fig. V. Plate VII.)nbsp;They are extremely nimble, and in a continual fwift Motion backwards and forwards;nbsp;but fometirnes they ftop on a fudden, andnbsp;turn round on their own Axis numberlefsnbsp;T imes with furprifing V elocity, firft one W aynbsp;and afterwards the contrary *. This Gyra-

* The Solar Microfeope has difeovered, that this ftrange Motion is produced by the Adlion of a great Number ofnbsp;i.egs or Fins, placed in a circular Order.

tion.

tion, or Twirling round as it were on a Point, I have taken Notice of in other Kinds alfo ofnbsp;the Animalcules found in Fluids.

Another pretty common Sort, and in Shape fomewhat refembllng the foregoing,nbsp;is fliewn (Fig. VI.) Their Motion is verynbsp;fwift, and always with the fharp End fore-moft, whence one may reafonably fuppofenbsp;it to be the Head. Some of them are clearnbsp;from End to End, but curioufly ribbed innbsp;the Manner of a Melon : others are tranf-parent at their fmall Extremity only, butnbsp;have their Bottle-end opake. No Legs ornbsp;Fins can be difeerned in either.

We find another Sort, as long almoft as the iargefi: in Fepper-Water, which are verynbsp;brifk and active, and have a Power of con-tra(ffing or extending thernfelves as theynbsp;fwim along. At the End that feems to benbsp;the Fore-part, feveral Feet are vifible j butnbsp;efpecially when the Water is almoft evaporated : for then they flirink into a globularnbsp;Form, and their Feet ftanding out may benbsp;perceived to move very nimbly. Fig. VII. i.nbsp;reprefents one of thefe Animalcules at itsnbsp;full Length: 2. fhews another of them whennbsp;contraifted.

There is likewife a Species of Animalcules whofe Bodies are fpherical, but pointednbsp;fomewhat like a Pear, and refembling Bladders filled with Water, wherein a vaft Number of dark Particles feem in a continual

Agitation. Their Motion is chiefly a re-* volving one, turning round perhaps abovenbsp;an hundred Times in a Minute, firfl onenbsp;V/ay, and then the contrary ; and all thisnbsp;without moving a Hair�s Breadth out ofnbsp;their Place. But fometimes they move forward very brifkly, turn, return, and fetch anbsp;large Compafs with fcveral Deviations ;nbsp;keeping, however, throughout their wholenbsp;Progreffion, their pointed End always fore-molt. See Fig. VIII.

I once dilcovered in the Scum on the Surface of Hay-Water a Kind of fnmute Serpents j for fo I call them from'their Motion, v/hich was like that of a Serpen t; and fromnbsp;their coiling up themfelyes in the Mannernbsp;Serpents do. I kept this Water ibme Weeks,nbsp;and fhewed them to feveral of my Friends jnbsp;but fince that Time have never met withnbsp;them in any Infufion of the fame Sort, or innbsp;any other Fluid, Their Manner of movingnbsp;forward, and alfo of coiling themfelves up,nbsp;is fl^ewn Fig. IX. i, 2. They were largernbsp;than any of the Eel-kinds of Animalcules,nbsp;their Motion very different, and not near fonbsp;quick. The End that feemed to be thenbsp;Plead was thicker and foinewhat more opakenbsp;than the other.

Animalcules in the Shape of Eels are fre^-quently met with in many of the Infulions 1 am now mentioning, and likewifc in fe-vcral other Liquors. The Bignefs of them

is very different, fome being an hundred Times larger than others, and probably theynbsp;may differ alfo very much in Kind. Theynbsp;have in general a nimble wriggling Motion :nbsp;but fome Sorts of them are more a�tive andnbsp;vigorous than others.

Vinegar, after ftanding a few Days uncovered, and efpecially in the Summer-Seafon, will frequently abound with a Kind of thefenbsp;Eels, large enough to be difcerned by thenbsp;naked Eye; 'which has encouraged fomenbsp;People erroneoufly to allert, that the Sharp-nefs of Vinegar is owing to nothing elfe butnbsp;the Striking of thefe Creatures upon thenbsp;Tongue and Palate with their pointed Tails;nbsp;whereas it is very certain, that many Timesnbsp;none of them can be difcerned even in thenbsp;foureft Vinegar ; and befides, Mr. Leeuwenhoek has demonftrated, that its Sharp-nefs proceeds only from the pointed andnbsp;penetrating Figure of the Salts floating innbsp;it, as I fliall find Occafion to obferve morenbsp;fully by and by.

Dr. Power tells us *, That if Vinegar wherein Eels abound be but moderatelynbsp;heated at the Fire, tliey will all be killed,nbsp;and fink down to the Bottom ; but thatnbsp;Cold does them no Injury. For after fuch

Vinegar had been expofed a whole Night to the fevered; Froft, and was frozen, and thawed, and frozen again, and fo feveral timesnbsp;over, they were as brifk as ever. He like-wife informs us, that in cold Weather henbsp;put fome Vinegar full of thefe Eels into anbsp;Glafs, and poured thereon about the famenbsp;Quantity of Oil, which floating on the Vinegar, all the Eth would conftantly creep upnbsp;into the Oil when the Vinegar began tonbsp;freeze �, but upon thawiqg the Vinegar, theynbsp;as conftantly returned to it again. Thefe arenbsp;pretty and curious Experiments.

A Drop of Oil of Vitriol, mixed with the Vinegar, kills them in the fame Manner asnbsp;Fire does.

If fome Grains of Sand be put among the Eels before the Microfcope, it will benbsp;highly entertaining to fee them ftrugglingnbsp;and embarraifed, as it were, amongd largenbsp;Stones.

CHAP.

[ 3i ]

CHAP. IV.

WHoever is defirous to be furniflied with yninute Eels always ready for thenbsp;Microfcope, needs only boil together a littlenbsp;Flour and Water, and make fuch Pafte thereof as Bookbinders commonly ufej or it maynbsp;be bought of them. It ftiould neither benbsp;very ftiff nor very watery, but of a moderate Confiftence. Expofe it to the Air in aanbsp;open Veflel, and prevent its hardening ornbsp;becoming mouldy on the Surface, by beating it well together when you find anynbsp;Tendency that Way j for if it grows hard ornbsp;mouldy, your Expedlation will be difap-pointed. After fome Days it will turn four ;nbsp;and then, if examined attentively, you willnbsp;difcern Multitudes of exceeding fmall, long,nbsp;Bender, wriggling Animalcules, which grownbsp;larger daily, till you will be able to feenbsp;them with the naked Eye.

To promote their coining forward, pour every now and then a Drop of Vinegar onnbsp;your Pafte : and after they are once produced you may keep them all the Year, bynbsp;putting to them fometimes a little Vinegarnbsp;or Water, if the Pafte becomes too dry, andnbsp;fometimes a little Supply of other fournbsp;Pafte j taking Care continually to preferve

the Surface in a right Condition, which will eafily be done when it is well flocked withnbsp;thefe Animalcules j the continual Motion ofnbsp;them preventing any Mouldinefs thereon.

A Water-Glafs, or fome other Glafs Vef-fel, is the moft convenient to keep your Pafte in j for, by holding it up againft thenbsp;Light, you will oftentimes perceive the Eelsnbsp;wriggling themfelves above the Surface ofnbsp;the Pafte upon the Sides of the Glafs, andnbsp;may be able to take feveral of them with anbsp;Pen or Hair Pencil, much more difengagednbsp;from the Pafte, and confequently fitter fornbsp;View, than if you are obliged to examinenbsp;the Pafte itfelf in order to find them in it.

Apply them to your Microfcope upon a fingle Talc or Ifinglafs, after having firft putnbsp;on it a very fmall Spot of Water for them tonbsp;fwim about in. The thicker your Pafte is,nbsp;and the more they are enveloped in it, thenbsp;greater Proportion of Water will be requifitenbsp;to dilute it, that they may difentangle themfelves, and be rendered diftindfly vifible.

They are vcrv entertaining Objefts examined by any Kind of Microfcope, but particularly the Solar one, by which I have magnified them fometimes to an Inch andnbsp;half, or two Inches in Diameter, with anbsp;Length proportionable, and have found themnbsp;anfwtr exaftly the Appearance of fuch fizednbsp;Pels. The internal Motion of their Bowelsnbsp;m;iy very plainly be diftinguiflied; and when

the Water is dried almoft away, and they are near expiring, their Mouths may be feennbsp;opening to a confiderable Width.

Mr. Leeuwenhoek fays, that at hrft he could difeern no living Creaturesnbsp;in Rain-Water ; but, after ftanding fomenbsp;Days, he difeovered innumerable Animalculesnbsp;many thoufand of Times lefs than a Grain ofnbsp;Sand, and in Proportion to a Mite as a Beenbsp;is to a Horfe.

In other Rain-Water, which had likewife flood fome Time, he found the fmallefl Sortnbsp;he had ever feen ; and in a few Days more,nbsp;met with others eight Times as big as thefe,nbsp;and almoft round.

In another Quantity of Rain-Water, that had been expofed like the former, he difeovered a Kind of Animalcules with two littlenbsp;Horns, in continual Motion. The Space between the Horns was flat, tho� the Body wasnbsp;roundifli, but tapering a little towards thenbsp;End, where a Tail appeared four Times asnbsp;long as the Body, and the Thicknefs of anbsp;Spider�s Web. He obferved feveral Hundreds of thefe within the Space a Grain ofnbsp;Sand would occupy. If they happened on

the leaft Filament or String, they were entangled in it, and then would extend their Bodies into an oblong Round, and ftrugglenbsp;hard to difengage their Tails. He obi'ervednbsp;a fecond Sort of an oval Figure, and imagined the Head to hand at the fharpeft End.nbsp;The Body was flat, with feveral fmall Feetnbsp;moving exceeding quick, but not difcerniblenbsp;without a great deal of Attention. Sometimes they changed their Shape into a perfeiTnbsp;Round, efpecially when the Water begannbsp;to dry away. He met alfo with a third Sortnbsp;twice as long as broad, and eight Timesnbsp;fmaller than the firfl:; vet in thefe he dif-cerned little Feet, whereby they moved verynbsp;nimbly. He perceived likewife a fourth Sort,nbsp;a thoufand Times fmaller than a Loufe�s Eye,nbsp;and which exceeded all the reft in Briflenefs;nbsp;he found thefe turning themfelves round, asnbsp;it were upon a Point, with the Celerity of anbsp;Top. And he fays there were feveral othernbsp;Sorts.

It is common, in Summer-time, for the Water that ftands in Ditches to appear fome-times of a greenilh and fometimes of a red-(difti Colour which, upon Examination

* TJie Infefts that moft commonly difcolour the Waters are of the Shrimp Kind, called by Swammerdam Pulexnbsp;a^uaticus arbore/ans, from the branching out of their littlenbsp;fdorns; they are often fo numerous in ftagnating Waters,nbsp;}n or June, at Which time they copulate, as to makenbsp;� �nbsp;nbsp;nbsp;nbsp;.nbsp;nbsp;nbsp;nbsp;-nbsp;nbsp;nbsp;nbsp;quot;nbsp;nbsp;nbsp;nbsp;.nbsp;nbsp;nbsp;nbsp;,nbsp;nbsp;nbsp;nbsp;them

with the Microfcope, is found entirely owing to infinite Millions of Animalcules crowdednbsp;together on the Surface of it, and giving itnbsp;fuch Appearance. Their Bodies are oval,nbsp;and tranfparent at both Ends; but the Middle either green or red, according to thenbsp;Colour of the Water they are fwimming in.nbsp;This middle Part, viewed with the firfi; ornbsp;fecond Magnifier, feems compofed of Globules, and bears fo near a Refemblance tonbsp;the Rows or Spawn of Fifhes, that it is rea-fonable to believe it really may be the fame:nbsp;and the more fo ftill, as they are found afternbsp;fomeTime perfe�tly clear and colourlefs, andnbsp;therefore may be prefumed to have fhednbsp;their Spawn.

The Water that drains from Dunghills, and looks of a deep brown Colour, is fonbsp;thronged with Animalcules, that it feems tonbsp;be all alive; and muft be diluted with Waternbsp;before they can be fufficiently feparated tonbsp;difiinguilh their various Kinds. Amongftnbsp;thefe one Sort is found, which I do not remember to have feen elfewhere, and therefore give a Draught of (Plate VIII. Fig. XI.)nbsp;Their middle Part appears dark, and befetnbsp;with Hairs, but both Ends of them tranf-them appear of a pale or deep red, and fometimes of a yellow Colour, according to the Colour of themfelves. Thenbsp;green Scum fo commonly feen on the Top of ftanding Watersnbsp;in Summer-time, is nothing but innumerable green Animalcules. Vid. Derham�s PhjJic. Theolog. pag. 178.

parent j their Tails are tapering, with a long Sprig at the Extremity; and their Motion isnbsp;flow and waddling. This Dunghill-Waternbsp;abounds alio with a Sort of capillary Eelsnbsp;that are extremely adlive.

An Infufion of any Herb, Grain, Fruit, or Flower, made in common Water, will benbsp;found, after a few Days, to contain fomenbsp;Kinds of Animalcules peculiar to itfelf; andnbsp;this, tho� aftonilhing, may be accounted fornbsp;in a very reafonable Manner; for a little Ob-fervation will fliew, that every Herb, Grain,nbsp;Fruit, or Flower, is allotted by Providence tonbsp;be the Food of fome particular Sort of Bird,nbsp;Beaft, or Infect, of the viflble and largernbsp;Kinds; and we may fuppofe it, in like Manner, when infufed in Water, to afford alfo anbsp;proper Nourifliment for fome or other ofnbsp;thofe numberlefs Species of minute Creatures,nbsp;which are invijible to the naked Eye, andnbsp;not to be difcovered without a good Micro-fcope. And as to this Particularity of Ani~nbsp;malcules, I refer the Curious (who have notnbsp;yet been convinced by Trials of their own)nbsp;to the Obfervations of Monfieur Joblotnbsp;(Frofe[Jhr Royal of the Mathematics, and ofnbsp;the Royal Academy oj Painting and Sculpturenbsp;at Paris) on the various Kinds difcoverednbsp;by him in the feveral Infufions following :nbsp;the Pidlures of which Animalcules he hasnbsp;given, as well as a Defcription of them. Henbsp;examined the Infufions of Pepper, black,

white, and long; of Senna^ of Pinks, of Cyanus or Bluebottle, of Rofes, JeJj'amin,nbsp;Rafpberry-Stalks, Pea, Barberries, Fennel,nbsp;and Hage, Marigold-Flowers, four Grapes,nbsp;and Mellion Rind; and found different Animalcules in them all. Hay, new and old,nbsp;abounded with many Kinds ; Rhubarb,nbsp;Mujhrboms, fweet BafiL, Citron-Flowers, hadnbsp;their particular Animalcules. The Anemo-ny afforded fome very wonderful *; Celery produced many Kinds ; Wheat-Ears znd.nbsp;Straw many Kinds ; Straw of Barley, Rye,nbsp;Oats, and Purkijh-Corn, many Kinds; Oak-Bark, new and old, afforded great Variety.nbsp;Some of thefe Infufions he kept a wholenbsp;Year round, and obferved, not only thatnbsp;each Infufion had Animalcules of Shapesnbsp;quite different from thofe in others, butnbsp;likewife that in the fame Infufion differentnbsp;Kinds of Animalcules appeared at differentnbsp;Times.

N. B. It is highly probable, that the Place where Infufions are made, in a City, or innbsp;the Country ; expofed to the open Air, ornbsp;fhut up within a Hoafe; as alfo the Seafonnbsp;of the Year, and its Temper as to Heat ornbsp;Cold, may occafion great Differences in the

f Mr. Joblot�s Draught of the Animalcules in this Infufion reprefents an exaft Satyr�s Face upon their Backs: I recommend the Trial to the Curious.

We fometimes find in our Infufions of vegetable ProduBions, and in other Watersnbsp;that have flood awhile uncovered, an Animal much larger than any before defcribed,nbsp;of a very fingular and furprizing Form, asnbsp;piaured Plate VIL Fig. XIL This littlenbsp;Creature is in its middle State; it lately wasnbsp;a Worm, and will foon become a Gnat.nbsp;For ¹ Gnats depofit their Eggs in a Kind ofnbsp;llimy Matter on the Surface of the Water,nbsp;and faften them to fomething that may prevent their being wafhed away, or feparatednbsp;too foon. Frorft thele Eggs proceed a Number of minute Worms, which, finking to thenbsp;Bottom of the Water, make for thernfelvesnbsp;Cafes or Coverings of fine Sand or Earth, cemented together with a Sort of Glue, butnbsp;open at both Ends for them to come out ofnbsp;or retire into as they find Occafion. After anbsp;Time, quitting thefe Habitations, and thenbsp;Figure of Worms, they re-afcend to the Topnbsp;of the Water in the Shape now before us,nbsp;fhelled all over, with a large Head andnbsp;Mouth, a Couple of black Eyes, two Horns,nbsp;feveral Tufts of Hairs or Briflles on differentnbsp;Parts of the Body, and a Tail with a Brufhnbsp;of Hair at the End of it, which being

SpeBach de la Nature, Engli^ Edit, \2ino, pag-Hooke�s nbsp;nbsp;nbsp;p. i8�.

fmeared over with an oily Fluid, ferves like a Cork to keep them above Water ; theirnbsp;Heads being fometimes lifted into the Air,nbsp;and fometimes plunged into the Water, whilenbsp;the Tail Hides along the Surface. And if thenbsp;Oil on the Tail begins to dry, they �hednbsp;from their Mouth a new Supply upon it,nbsp;which reftores its Ability of Iteering wherenbsp;they pleafe, without being wetted or prejudiced by the Water. After living in thisnbsp;Manner the Time appointed by Providence,nbsp;a flranger Change fucceeds: for, religningnbsp;their Eyes, Horns, and Tail, and calling offnbsp;their whole Skin, there iffues forth a Racenbsp;of Infe�ls of a quite different Element: thenbsp;moft beautiful and delicate Plumage adornsnbsp;their Heads ; their Limbs are conftitutednbsp;with the fineff 1 exture ; they have Wingsnbsp;curioufly fringed and ornamented; theirnbsp;whole Bodies are invefted with Scales andnbsp;Hair, and they are actuated by a furorizingnbsp;Agility : in Ihort, they become Gnats, andnbsp;fpring into the Air. And, what is moftnbsp;amazing, a Creature that but a Minute fincenbsp;was an Inhabitant of the Water, would nownbsp;be drowned if it were plunged therein.

I have been the more particular in my Account of this Metamerphojis, as I apprehend many Sorts of the Animalcules in f luidsnbsp;undergo Changes in fomewhat a like Manner. I fhall only add here, that thenbsp;little Creature whofe Pidure I have given,

is a delightful Obje�f for the Microfcope-, its white Heart beating diftindtly, and the Motion of all its Inteftines being perfedlly vifi-ble and extraordinary.�Of the Gnat I ihallnbsp;fpeak farther in its proper Place.

The Waters every where abound with Life, and are an endlefs Subjedl of Employment for the Microfcope : Seas, Rivers,nbsp;Ponds, Ditches, and almoll: every Puddlenbsp;can, by its Affiftance, prefent us with livingnbsp;Wonders never before difcovered : for fuchnbsp;Examinations have as yet been but little attended to, even by People that have gotnbsp;thefe Inftruments, and alfo a Genius to ufenbsp;them. But I am in hopes this Treatife maynbsp;excite them to be more induftrious, and notnbsp;fuffer a little Difficulty, or a few Difappoint-ments, to difcourage them from a Studynbsp;that can fo amply reward their Pains.

In feveral of * Mr. Leeuwenhoek�s Letters to the Royal Society, we meet withnbsp;an Account of fome furprizing Animalculesnbsp;found adhering to the Roots of the Lensnbsp;Ralufris, ox Luck-Weed (which in Summertime floats plentifully on the Surface ofnbsp;Ponds and Ditches), as examined by him innbsp;a Glafs Tube filled with Water. One Sort

of thefe was fhaped like Bells, with long Tails, whereby they faftened themfelves tonbsp;the Root of thefe Weeds; and fometimesnbsp;twenty of thefe were feen together, gentlynbsp;extending their long Tails and Bodies, andnbsp;then, in an Inftant, con trailing them again.nbsp;See the Draught, Plate VIII. Fig. I.

A, reprefents a Root oiDuck-Weed, with the Tails of mzny Animalcules adhering to it.nbsp;b b b b, fhew their Bell-like Bodies.nbsp;c c c c, their long Tails.

Another extraordinary Kind of Animacule (which fee Fig. II.) appears in a Sheath ornbsp;Cafe, a, b, c, the End whereof it fallens tonbsp;the Duck-Weed Roots. This little Creaturenbsp;has two feeming Wheels with a great manynbsp;Teeth or Notches coming from its Head,nbsp;and turning round as it were upon an Axis,nbsp;d, e. At the leall Touch it draws the Wheel-work into its Body, and its Body into thenbsp;Sheath, after which it appears as Fig. III.nbsp;But when all is quiet, it thrulls itfelf outnbsp;again, and the Rotation of the Wheel-worknbsp;is renewed. Mr. Leeuwenhoek took Notice of one of thefe, whofe Cafe feemed com-pofed of minute Globules (Fig. IV. a, b.)nbsp;and in this he difcovered the Wheel-work tonbsp;confift of four roundilh Parts, with little Di-vilions between each, though only three ofnbsp;thofe roundilh Parts could be feen, the fourthnbsp;lying behind, as reprefented Fig. V. Thisnbsp;convinced him how much he had been mif-

taken, in believing them, from their com-� mon Appearances, to be two Wheels,nbsp;whereas the real Form of this Wheel-worknbsp;is as at Fig. V.

To find thefe A7imalcules, choofe Duck-Weed that has long Roots; for young Plants with Ihort Roots feldom aiford any. Benbsp;careful too that they are not covered with anbsp;rough Matter, or tending to Decay, as theynbsp;will often be. Let the Roots fink gentlynbsp;down in a Glafs Tube filled with Water,nbsp;and fo apply them to the Microfcope. Twonbsp;or three Animalcules will be found fometimesnbsp;adhering to one Root; and at other timesnbsp;you may examine feveral, and not be able tonbsp;meet with any.

In the Water, or flimy Matter, found in Leaden Pipes or Gutters, Mr. Leeuwenhoek met with various Kinds of Animalcules^ and, among the reft, with Multitudesnbsp;that appeared to have a Sort of Wheel-work,nbsp;turning round fomewhat in the former Manner *. Thefe Creatures, when the Waternbsp;dries away, contrail their Bodies into a globular or oval Figure, and reddifh Colour, andnbsp;become fixt in the dry Dirt, which growsnbsp;as hard as Clay : but whenever a Piece ofnbsp;fuch Dirt is put in Water, in about half annbsp;Hour�s 1 ime they open, and by Degrees ex-

tend their Bodies, and fwim about: and this they did after fome of this Gutter-Dirt hadnbsp;been kept dry for twenty-one Months together. Whence he concludes, that the Poresnbsp;of their Skin are clofed fo perfectly, as tonbsp;prevent all Perfpiration; by which Meansnbsp;they are preferved till Rain falls, when theynbsp;open their Bodies, fwim about, and take innbsp;Nourifhment.

We may find in the Waters of our Ditches feveral Species both of Teftaceous and Cruf-taceous Animalcules: two of the latter Sort,nbsp;which are moft remarkable, are fhewn (Platenbsp;IX. Fig. I. and II.) in a fwimming Pofture,nbsp;with their Backs towards the Eye. Theirnbsp;Legs are fomewhat like Shrimps or Lob-fters, but of a much more curious Strudlure.nbsp;They are lefs than a very fmall Flea, butnbsp;are all Breeders, and carry their Spawn eithernbsp;under their Tail, or in two feeming ¹ Bagsnbsp;hanging from their Sides, as in Fig. II.nbsp;Thefe Bags may fometimes be obfervednbsp;Broken, and the Spawn (confifting of Globules very large in Proportion to the Crea-

ture) fcattered about the Water. There is alfo a third Sort, as beautiful as the foregoing, but not near fo large ; its Shape morenbsp;refembles a Shrimp, and it carries its Spawnnbsp;as the Shrimp does. Thefe three Species ofnbsp;Animalcules appear to have only one Eye,nbsp;and that placed in the Middle of the Forehead, without fo much as the leaft Trace ofnbsp;even a dividing Line. They are often to benbsp;found fo tranfparent, that the Motion ofnbsp;their Bowels is feen diftindlly by the Micro-fcope, together with a regular Pulfation in anbsp;little Part, which therefore we may fuppofenbsp;to be the Heart.

I fhall finilh this Head with defcribing a very wonderful Kind of minute Animal,nbsp;the extraordinary Form whereof (aboutnbsp;thrice the Bignefs it appeared to the nakednbsp;Eye) whilft in the Water, and faftened tonbsp;the Root of a Weed, is given Fig. III. Thisnbsp;was a large one of the Sort, and had eightnbsp;Horns; whereas the fmaller ones have fel-dom more than fix. It is likewife fhewnnbsp;here as extended to its full Length, butnbsp;when contracted is not a fourth Part fo long.nbsp;It fixes by the Tail to the Roots or Stalks ofnbsp;Water-Plants. On the upper Side a verynbsp;fmall Animalcule faj is reprefented comingnbsp;out of the other�s Body. This was fuppol-ed at firlt to have faftened itfelf there bynbsp;fome Accident but, by obferving it narrowly.

fowly, it was difcovered to be a young one in the Birth ; for though it had but four verynbsp;finall Horns when firft feen, after fixteennbsp;Hours its Horns and Body were grown muchnbsp;larger j and in four Hours more it was quitenbsp;excluded its Mother�s Body. Againft this*'nbsp;on the upper Side, appeared a little roundnbsp;Knob, which gradually increafed in Bignefs,nbsp;and in a few Hours became pointed at f�j.nbsp;Thirteen or fourteen Hours after, it wasnbsp;grown much larger, and alfo had two Horns.nbsp;In twenty-four Hours four Horns were feennbsp;upon it, one whereof was fmall, the fecondnbsp;larger, and the other two very -large, extending and contradling more vigoroufly thannbsp;their Fellows. Three Hours afterwards thisnbsp;Animalcule likewife fell off from its Mother,nbsp;and Ihifted for itfelf.

The above Account is the Subdance of Mr. Leeuwenhoek�s Letter to the Royatnbsp;Society, Phil. �Tranf. Numb. 283.�And innbsp;Numb. 288. we meet v/ith a farther De-feription of the fame Animalcule by an Png-JiJJj Gentleman, whom Mr. Leeuwenhoek�s Relation had put upon hunting afternbsp;it. He fays, he difcovered one of them innbsp;fome clear Water taken out of a Ditch, butnbsp;with the utmoft Attention could find no morenbsp;therein. It appeared the firil Day as in Fig.nbsp;IV. but he tells us it varied every Moment,nbsp;and the Knob (a), which looks like th�nbsp;Vol. I.nbsp;nbsp;nbsp;nbsp;FInbsp;nbsp;nbsp;nbsp;Gut

Gut Cacum, was fometimes a little longer'. Two or three Days after, he perceived fomenbsp;white Fibres at the Extremity of the Knob jnbsp;and on the fourth Day it lay extended at fullnbsp;Length, and appeared as in Fig. V. and henbsp;was then convinced, that what he imaginednbsp;an Excrefcence, was in Reality a youngnbsp;Animalcule of the fame Species, iffuing fromnbsp;the old one, and having fix Horns. Nextnbsp;Day he found it in the Water entirely fepa-rated, and about a third of its Parent�s Length.nbsp;The Horns come out like Radii, not fromnbsp;the Extremity, but quite round a fmall Knob,nbsp;which probably is the Head : they have anbsp;vermicular Motion, and can extend or con-trad; themfelves either fingly or altogether.nbsp;The other End is flat, and by that it oftennbsp;faftened to the Bottom or Side of the Glafsnbsp;wherein he kept it. It alfo contrads andnbsp;dilates its Body, and can bring both Bodynbsp;and Horns into a fmall Com pafs, as innbsp;Fig. VI. and Fig. VII. The Horns are per-fedly white, the Body yellowilh, and notnbsp;eafily difcernible by the naked Eye; being,nbsp;when extended, no thicker than a largenbsp;Horfe-Hair.

Monf. Buffon, in a Letter to Martin Folkes, Efq. late President of the Royalnbsp;Society, dated at the Garden of Verjailles,nbsp;'July i8, 1741, fends an Account (as a newnbsp;Difeovery in Natural Hiftory) of a Creature

Called a Polype ¹, found adhering to the Pens Palujiris; which being cut through thenbsp;Middle, from the upper Half a Tail proceeds, and from the lower Half a Head : fonbsp;that one Animal becomes two. If it be divided into three, the middle Part (hoots forthnbsp;a Head and Tail, the upper Part a Tail, andnbsp;the lower Part a Head �, and all three become as perfedt Animals as the firft. Whencenbsp;he concludes, that in the boundiefs Varietynbsp;of the Works of Providence, every Thingnbsp;that can be, is.

Another Letter to the fame Gentleman, dated at the Hague, Sept. 15, 1741, from thenbsp;Honourable William Bentinck, Efq.nbsp;fays. That a young Man of Geneva lookingnbsp;for fmall Infedts in Water, faw fome littlenbsp;Things which he took for Plants; but examining them carefully, he perceived fomenbsp;Motions in them, and found them contradtnbsp;when touched. It was a long while, however, before he could determine whether theynbsp;were Plants or Animals ; for he faw feveralnbsp;young /Shoots coming out upon them, andnbsp;that as far as four Generations, hanging tonbsp;ene another. But he has lince found them

The Name Polypus, or Many Feet, is given to feveral Fiflies of the Slar-Fijh or Cuttle-Fijh Kind, fome whereof,nbsp;befides feveral Claws, have two long Trunks, which theynbsp;can extend to a great Dillance to feize their frey ; and thisnbsp;Animalcule, I fuppofe, is called Polype, from its having foine-what of a like Form.

to eat Infeds, and even raw Meat. They failen themfelves by one Extremity to lomenbsp;Plant, or the Side of a Glafs, and have atnbsp;the other End fix or eight Horns, wherewith they hold their Prey.

He cut one of thefe Creatures to fee what Would become of it, and fome Days afternbsp;found new Arms growing out where othersnbsp;had been cut away. Since that, he has divided them the long Way, the broad Way,nbsp;oblique, and every Way poffible, all withnbsp;the fame Saccefs. He has alfo gone on fub-dividing them, and has not found them propagate any other Way than by Shoots, andnbsp;without Copulation.

Both thefe Letters feem to mean the fame Animalcule Mr. Leeuwenhoek defcribes:nbsp;though with farther extraordinary Particulars, which I believe the Curious will judge itnbsp;worth their while carefully to examine into^.

* Since the Publication of the above Accounts, fuch farther Particulars concerning this Animalcule have been received bothnbsp;from Holland and Francs, in Anfwer to the ingenious Enquiries of Martin Folkes, Efq. Prcfident of the Royal Society, and by him communicated to the faid Society, thatnbsp;it would appear an unpardonable Negledt Ihould I take nonbsp;Notice of them.

The Honourable William Bentinck, Efq. F. R. S. in a Letter from the Hagus, dated 15th 'January, N. S. 1743,nbsp;inclofcs fomc Obfeivations and Experiments drawn up bynbsp;Mr. Trembley (the young Gentleman mentioned p. 97.nbsp;as ihe firlf Difeoverer of the Singularity of this Infedl, who

Animalcules in Waters.

Upon the Whole, this Animalcule appears to be fomewhat of the Star-Fiji Kind, ornbsp;between that and the Sea-Mujhroom, ornbsp;Anemone: which is a little Animal found

now refides in Holland); and Mr. Bentinck adds, that he can anfwer for the Truth of the Fads therein contained, asnbsp;there is not one of them but what he has feen repeated abovenbsp;twenty times.

Mr. Tremel EY gives a Drawing of xhe Polype, with eleven Horns, or Arms, and adhering to the Tail by a little Twig;nbsp;but in all other refpedts exaftly conformable to Fig. JV. andnbsp;V. Plate IX. The Horns, he fays, ferve for Legs and Arms ;nbsp;and at the End whence they come out is a Mouth, or Paflagenbsp;into the Stomach, which, extending the whole Length, formsnbsp;a Body like a Pipe or Gut, open at both Ends. He knowsnbsp;two Species, and has feen fome ftretch their Bodies to annbsp;Inch and half in Length, but that is rare ; few,.even of thenbsp;larger Kind, being above nine or ten Lines long: and fiichnbsp;can contrad themfelves to not above a lingle Line. Hopping,nbsp;if they pleafe, at any Degree, between the utmoft Contradionnbsp;and the utmoft Extenlion. Their Horns differ in Length according to the Species; one Sort can extend them (even Inches;nbsp;their Number of Horns is alfo different; but a full-grownnbsp;Polype has feldom Ie(s than fix.

They do not fwim, but crawl, either upon the Ground, oa aquatic Plants, Pieces of Wood, Leaves, all which are tonbsp;be taken from the Bottom, Surface, Edges, or Middle ofnbsp;Ditches (when we hunt after thefe Animals) and put into anbsp;Glafs of clear Water ; where, after a little Reft, if there benbsp;any Polypes, they will be feen to extend their Arms, whichnbsp;they contraded upon being difturbed.

Their common Pofture is, to fallen their Tails to fome-thlng, and then extend the Body and Arms into the Water ; and they make ufe of their progreftive Motion to place themfelves conveniently for this Purpofe. Their Arms are fo manynbsp;Snares, ftretched out to catch (mail Creatures in the Water;nbsp;and when any,Infed happens to touch an Arm, it is caught,nbsp;and conveyed to the Mouth by the contrading of that Arm ;nbsp;or if the Creature ftruggles, the other Arms allift.

They are voracious Animals : a Polype can fwallow a Worm whole twice or thrice its own Length. If the Worm come^

Animalcules in Waters.

Endways, it is fwallowed in that Manner ; otherwife it goes down double, and makes feveral Foldings in the Stomach,nbsp;which diftends wonderfully for its Reception. The Wormnbsp;foot) dies there, and after it has been fqueezed or fucked, isnbsp;voided by the Mouth. They eat more or lefs, feldoiner ornbsp;oftener, as the Weather is hotter or colder, and grow in Proportion to what they eat: they can live whole Months without Food, but wafte proportionably to their falling.

He fays, the Account (in the Pbilo/ophical Tran/a�lions before quoted, p. 95.) of the Manner how thefe Infedts multiply, is true and exadl ; and the more one fearches into it,nbsp;the moie evidently it will appear to be done by a true Vegetation. The Polype brings forth its Young from the exteriornbsp;Parts of the Body, and that not always a fingle young one atnbsp;once : it is common to fee five or fix, nay fometimes nine ornbsp;ten at the fame Time ; and when one drops off, anothernbsp;comes in its Place.

For two Years, thoufands of them have been under his Eye, but he could never obferve any thing like Copulation amongftnbsp;them. And left it Ihould happen in fome fecret Manner between the Old and Young, he has feveral Times cut off anbsp;young one from its Parent, and kept it in a Glafs alone ;nbsp;notwithftanding which, it bred very plentifully. And thatnbsp;ro Copulation might pofiibly be performed between thenbsp;young ones themfclves, he has cut them oft', one by one, asnbsp;they Iprouted out, and has kept each of them alone, and thatnbsp;for feven lucceflive Generations, but without finding anynbsp;Difference as to their increafe. He has likewife feen a Polypenbsp;bring forth young ones, and thole again producing others,nbsp;before the iirft has been fepaiated from its Parent. Theynbsp;multiply more or lefs, in proportion to their Feeding, andnbsp;the Warmnefs of the Weather.

But the moll amazing Part of Mr. Tremble y�s Account is, what he tells us concerning his Operations on thefe Creatures.nbsp;If one of them be cut in two, tranfverfely, the Fore-part,nbsp;which contains the Head, Mouth, and Arms, lengthens it-felf, creeps, and eats, on the very fangt;e Day. The Tail-partnbsp;forms a Head and Mouth at the wounded End, and lliootsnbsp;forth Arms, more or lefs fpeedily as the Heat is favourable.nbsp;In Summer they will be Ihot out in twenty-four Flours, andnbsp;the new Head perfefled in a few Days.

Cut a Polype where or in what Parts you pleafe, tranfverfely, each Part becomes a compleat Polype. But being too fmall an Animal to admit of being divided into many Parts at

once.

.Animalcules in Waters.

once, he firft cut one into four Quarters, and let them grow J then divided each Quarter, and proceeded fubdividing till henbsp;obtained fifty out of one ; and has ftill by him feveral Piecesnbsp;of the fame Polype thus cut above a Year ago, which havenbsp;produced Numbers of young ones.

If a Polype be cut the long Way, through the Head, Stomach, and Body, each Part is half a Pipe, with half a Head, half a Mouth, and fome of the Arms at one of its Ends. Thenbsp;Edges of thefe half Pipes gradually round themfelves, andnbsp;unite, beginning at the Tail-End ; and the half Mouth andnbsp;half Stomach of each becomes compleat. All this he hasnbsp;feen done in lefs than an Hour ; and the two Polypes thusnbsp;formed differed nothing from whole ones, but in havingnbsp;fewer Arms ; which Defedl a few Days fupplied. A Polype hasnbsp;been cut lengthways between Seven and Eight in the Morning, and between Two and Three in the Afternoon each Partnbsp;has devoured a Worm as long as itfelf.

Cutting a Polype lengthways, through the Head and Body, but not quite through the Tail, in a (hort Time there will benbsp;two perfect Heads and Bodies with but one Tail: which Headsnbsp;and Bodies may, foon after, be again divided in like Manner :nbsp;and thus, Mr. Tremblf y fays, he has produced uPolype withnbsp;feven Heads and Bodies conjoined with but one Tail. Thefenbsp;feven Heads being cut off at once, feven others grew in theirnbsp;(lead ; and each of the feven Heads fo cut off, putting forthnbsp;a new Body, became a compleat Polype.

He cut a Polype tranfverfely afunder, and putting the two Parts clofe together, they united where they had been cut.nbsp;The Creature eat the next Day, is grown fince, and has multiplied. The Fore-Part of one Polype united in the famenbsp;Manner to the Hind-Part of another. This compound Animal eat likewife the next Day, and has fince produced youngnbsp;ones from each of the Parts that formed it. But thefe twonbsp;Experiments do not always fucceed.

It was faid before, that the Body of a Polype is a Sort of hollow Gut or Tube : this he has found means to turn infidenbsp;out, as one may turn a Stocking; and has feveral at prelencnbsp;by him, whofe Infides remain to be their Outfides; notwith-llanding which, they eat, grow, and multiply, as if nothingnbsp;had been done to them. He has repeated ail thefe Experiments feveral Times with the utmoit Precaution, Affiduity,nbsp;and Attention; and might appeal, he fays, to the Q__alitynbsp;and Number of the Perfons who have feen them made bynbsp;him, a-s well as of thofe who have made the fame themfelves.

H4 nbsp;nbsp;nbsp;He

Animalcules in Waters.

He adds, that in the Hiftory of the Polype, which he has Jtt � Hand, all the Methods and Contrivances ufed by him in hisnbsp;Obfervations will bedefcribed ; but even before its Publication he is ready and willing to communicate any Information that may enable others to perform the like.

Mr. Reaumur, Fellow of the Royal Academy of Sciences in France, declares (in the Preface to the lixth Volume of hisnbsp;Ilifiorfof lnfe3s]V.'}i publillied zX. Paris) that he has repeated allnbsp;Mr. Trembley�s Experiments, notonly by himfelf, butwith.nbsp;Mr. Jussieu, and feveral others of the faid Academy, andnbsp;found them fucceed as they had done in Holland, of which henbsp;gives a general and fuccinft Account. When firli he faw twonbsp;compleat Animals forming themfelves from the Parts of onenbsp;Polype cut afunder, he knew not, he fays, how to believe hisnbsp;pyes ; and he cannot yet behold it without new Amazement,nbsp;though he has feen it an hundred and an hundred Times. Henbsp;adds, that the Curious in France foon began to try if othernbsp;Creatures might not be found with the fame extraordinarynbsp;Faculty. That Mr. Bonnet foon difcovered a Bender Water-Worm about one Inch and half long, that had the famenbsp;Property ; and Mr. Lyonett found another about threenbsp;Inches long, and the Thicknefs of the treble String of anbsp;Violin, which being cut into thirty or forty Parts affordednbsp;the fame Phsenomena.

Mr. Reaumur, imagining that fome Sea Produdlions, whofe Shape fomewhat refembles this Frejh-Water Polype,nbsp;fuch as the Urtieas Marine and Star-Fijh, might have thenbsp;like Faculties, engaged Mr. Guttarb and Mr. Jussieunbsp;, to make Variety of Experiments on the Coafts ot PoiStou andnbsp;Hormandy. They broke and cut Star-FiJh into feveral Parts,nbsp;and had the Pieafure to fee the feveral Parts continue alive,nbsp;and their Wounds cicatrize and heal: and though they couldnbsp;not flay long enough in the Country to fee new Parts Ihootnbsp;forth inftead of thofe cut away, Mr. Gerrard de Viltnbsp;LARS has feen the Urtica, on the Coafts ncAT Rochelle, re-produce all the Parts cut off, and the Star-Fijh putting forthnbsp;new Radii in the Room of thofe they had been deprived of.nbsp;When the Filhermen faw Mr. Jussieu tearing and cuttingnbsp;one of thefe Animals in Pieces, they told him, it was Labournbsp;in vain, he could not kill it; Experience having taught themnbsp;what Men of I.earning had never fo much as heard of.nbsp;Mr. Reaumur and Mr. Bonnet found alfo fome Sorts ofnbsp;Earth-Worms, which being cut in two, each Half had all itsnbsp;Deficiencies re-pioduced after fome Months. Many, indeed,

Ammalciiles in Waters.

frequently on the Coafi; of Nortnandy *. They are feen flicking on the Declivity ofnbsp;Rocks, foine red, fome green, and fomenbsp;of other Colours ; where they look likenbsp;Muflirooms while fhut and folded up, butnbsp;like Anemonies when they open and difplaynbsp;themfelves. There is no opening them bynbsp;P'orce without deftroying them �, but on Pref-fure they fometimes ejedt feverai young onesnbsp;of different Sizes : v/hich feems to provenbsp;them both Male and Female, and alfo to be

died ; but as fome fucceeded, the Mlfcarriages muft be imputed to Want of Care, and not to the Want of fuch an Ability in thefe Animals.

It may, perhaps, be expefled of me to add here fome fiirther Relation of this extraordinary Creature, as it is well knownnbsp;by many, that for a Year and half pall great Numbersof theinnbsp;have been continually under my Examination ; but havingnbsp;lately publilhed whatever 1 can atteft concerning it from mynbsp;own Knowledge, under the Title of y/� EJfay tonuards a Natural Hijlory of the Polype (wherein I defcribe their differentnbsp;Species, the Places where to feek and how to find them, theirnbsp;wonderful Produdlion andincreaf?, the Form, Strudlure, andnbsp;Ufe of their feverai Parts, and the Manner they catch theirnbsp;Prey ; with an Account of their Di/ea/es and Cures, of theirnbsp;zmz��xig Re-produSlion after being cut in Pieces, of the bell Methods to perform that Operation, and of the Time requilite tonbsp;perfeft the feverai Parts after being divided : and alfo full Di-redlions how to feed, clean, manage, and preferve them at allnbsp;Seafons oftheYear : Wkewik s.Courfe of real Experiments, performed by cutting them every Way that can be eafily contrived ; Ihewing the daily Progrefs of each Part towards becomingnbsp;a perfeft Polype ; the Whole explained every where by greatnbsp;Numbers of Figures, and intermixt throughout with Varietynbsp;of Oh/ervations and Experiments) ; I mull refer my Reader tonbsp;that hffay ; as an Abllradt thereof would not only over-fwellnbsp;this Volume, but likewife prove an Injury to thofe who havenbsp;Jsought the former Editions.

viviparous.

viviparous. If you loofen their Hold, carry them away, and keep them in Water, theynbsp;will fix themfelves to the firft convenientnbsp;Place they find. When the Sea-Mujhroomnbsp;is about to open, it raifes itfelf, and thruftsnbsp;out two little white and ftriped Bodies likenbsp;Bladders, round which appears a great Variety of Points or Trunks of different Sizesnbsp;and Colours; whence fome Naturalifts havenbsp;called it the Sea-Aitemone. This Opening,nbsp;not unlike the blowing of a Flower, hasnbsp;inclined others to look upon it as a Sort ofnbsp;Plant, or elfe as partaking both of the Animal and Vegetable Nature. But fince allnbsp;thefe little Points or Studs are not Leaves,nbsp;but a Sort of Snouts or Trunks, throughnbsp;which this Creature fucks in its Nourifb-ment, as the Sea-Urchin and Star-Fijh donbsp;through their fine Reeds or Prickles, wenbsp;cannot deny it a Place in the Rank of Animals ; and efpecially after fo remarkable anbsp;Circumftance (confirmed by ocular TefH-mony) as that of three or four young onesnbsp;iffuing from the Parent upon fqueezing it.

There is a Sort of Star-Ftjh, called by Rondf.letius, p, I2I, Stella Arborefcensynbsp;which, from a Body fomewhat like the Sea -Urchin^ fends out five Branches in Form ofnbsp;a Star: thefe five divide into ten; thofe tennbsp;again into twenty; the twenty into forty jnbsp;the forty into eighty; the eighty into onenbsp;hundred and fixty; the one hundred and

fix tv

fixty into three hundred twenty j the three hundred twenty into fix hundred forty; thenbsp;fix hundred forty into one thoufand twonbsp;hundred eighty; the one thoufand two hundred eighty into two thoufand five hundred fixty; the two thoufand five hundrednbsp;fixty into five thoufand one hundred twenty;nbsp;the five thoufand one hundred twenty intonbsp;ten thoufand two hundred forty; the tennbsp;thoufand two hundred forty into twentynbsp;thoufand four hundred eighty; the twentynbsp;thoufand four hundred eighty into fortynbsp;thoufand nine hundred fixty; and thofenbsp;again into eighty-one thoufand nine hundrednbsp;twenty.�The farther Divifions could notnbsp;certainly be traced; tho� probably whennbsp;the Fifh was alive they might have beennbsp;diftinguiflied much beyond this Number*.nbsp;All thefe flender Threads, thro� their wholenbsp;Length, have minute Clafpers iffuing fromnbsp;them, and appear very amazing when examined by the Microfcope.

To conclude this Chapter.�If the fmall-eft living Creatures that have been yet dif-covered are produced in the Waters, in them we find alfo the largeft and mofl monftrous.nbsp;No Bird orBeaft comes near the Size of manynbsp;Kinds of Fifhes, nor can the Elephant itfelfnbsp;be brought in Comparifon with the Whale.

Joannes Faber Lynceus aflures us, that, in the Year 1624, he faw himfelf anbsp;Whale that was caft upon the Shore nearnbsp;Santa Severa, about thirty Miles from Rome,nbsp;ninety-one Palms in Length, and fifty innbsp;Thicknefs : its Mouth was fixteen Palmsnbsp;long and ten high, and being opened andnbsp;kept gaping, a Man on Horfeback mightnbsp;therein find Room enough. Its Tongue wasnbsp;twenty Palms, that is, about fifteen Foot innbsp;Length. He adds, that four Years before,nbsp;another Whale was thrown afhore near thenbsp;Ifland of Corjica, not far from the Coaft ofnbsp;Italy, which, being a Female, was found bignbsp;with a Cub thirty Foot long, and fifteennbsp;hundred Pounds in Weight, He fays, thenbsp;Carnea Pinguedo [Lard or Fat] only of thenbsp;Parent Whale weighed one hundred andnbsp;thirty-five thoufand Pounds.

Let us now refle6l how amazing the Dif-parity between fuch a Filh as this, and a minute Animalcule lefs than the thoufandthnbsp;Part of a Grain of Sand in Bignefs ! hownbsp;innumerable mufi: the Kinds of Creatures benbsp;that form the Progreflions from one Size tonbsp;the other ! and how equally wonderful doesnbsp;the Hand of Providence appear, whether itnbsp;a�luates an enormous Mountain of Matter,nbsp;or enlivens an Atom !

C H A P.

[ 103 3

WE cannot employ the Microfcope to any more ul�eful Purpofe than tonbsp;view the natural Courfe of the Blood withinnbsp;its Veffels, or examine the Contexture of itnbsp;when extradled from them : for the Prefer-vation or Reftoration of the Health of Mannbsp;may be greatly advantaged by fuch Enquiries.

By feeing it within the Veflels, we may judge of the Situation, Dimenfions, Arrangement, and Ramifications of the Arteries andnbsp;Veins through which it paflTes, together withnbsp;the general State of the Fluid, the Degreenbsp;of its Impulfe, Progreffion, or Motion, andnbsp;the Tendency or Direction of its Currentnbsp;palTing through them.

When taken from the Vefiels, we can examine it more minutely, and obferve allnbsp;the little Alterations that may happen in thenbsp;Mixture, Size, Form, and Quality of thenbsp;Particles compofing its more folid or morenbsp;fluid Parts.

I fhall now fhew how the Microfcope may be employed in both thefe Ways; but thinknbsp;proper to premife a fhort Account of the Bloodnbsp;itfelf, fince our Knowledge of that will thenbsp;better enable us to make a right Judgmentnbsp;when we come to fee it circulate.

CHAP.

CHAP. VII.

TJTJMAN Blood, and the Blood of Land-Animals, is found by the Microfcope to confift of round red Globules fioating innbsp;a tranfparent Water and Serum. Each rednbsp;Globule is made up of fix fmaller and morenbsp;tranfparent ones : and Mr. Leeuwenhoeknbsp;has difcovereq, that each of thefe again isnbsp;compofed of fix Globules ftill more minutenbsp;and colourlefs : fo that every common rednbsp;Globule is compounded of at leaft thirty-fix fmaller ones ; and perhaps the Divifionnbsp;may ftill go on much farther ¹.

The fpecific Gravity of thefe Globules is fomewhat more than of the Serum whereinnbsp;they float, as is fhewn by their fubfiding innbsp;Blood extracted from the Veins and at reft :nbsp;they have alfo a confiderable Attradlion tonbsp;each other, and when brought in Contact,nbsp;cohere fo ftrongly (unlefs fcon feparatednbsp;again by Motion) as to form a Subftance re-fembling foft Flefh.

It is not difficult to imagine, how fix foft and flexible Globules, eafily compreffiblenbsp;into any Shape, may compofe one largernbsp;Globule : but to make it the better under-

Fig. I. Plate X. fhews one fuch large Globule, wherein five of the fmaller Sortnbsp;that compofe it appear in Contad:, the fixthnbsp;lying behind.

Fig. II. fhews how, by their mutual At-tradion to, or Preffure againfi: each other, they readily unite to form a perfed roundnbsp;Body.

It is alfo eafy to conceive, that thefe fix Globules, and even the more minute onesnbsp;ftill whereof they are compounded, maynbsp;occafionally be feparated, in order to pafsnbsp;through fuch extremely minute Veflels asnbsp;without Separation they cannot poffibly enter ; and may re-unite when they meetnbsp;again in Veffels where they have more Room.nbsp;And we are very certain, that fometimesnbsp;they cohere in greater Numbers, and formnbsp;larger Maffes, than are confident with a freenbsp;and healthy Circulation.

Mr. Leeuwenhoek and Dr. Jurin, after the moft accurate Admeafurement, by the Way deferibed page 46, agreed, that thenbsp;Diameter of a common red Globule of human Blood is equal to the * one thoufandnbsp;nine hundred and fortieth Part of the Lengthnbsp;of an Inch. Mr. Leeuwenhoek before

this had computed that ¹ twenty-five thou¹ fand of them were but equal to a Grain ofnbsp;Sand.

Suppofing, then, the Blood in People of found Health to confift of Globules of fuchnbsp;Size and Compofition as before mentioned,nbsp;foft, flexible, and eafily feparable j it mu ftnbsp;necelTarily happen, that a confiderable Alteration in any of thefe Particulars will occa-fion a morbid State.�Should the Globules,nbsp;for Inftance, be divided too minutely, and notnbsp;readily again cohere 3 fhould they becomenbsp;rigid and unflexible, either when feparated ornbsp;united 3 or IhOuld they coagulate and becomenbsp;infeparable, bad Confequences miift enfue.

The great B�erhaave fays, that Health confifts in an equal Motion of the Fluids,nbsp;and an equal Refiftance of the Solids. Nownbsp;the Fluids move equally when their Forcenbsp;is not greater in one Part than in another 3nbsp;and the Refiftance of the Solids is equalnbsp;when they comprefs the Fluids every wherenbsp;fo equally, that no Senfe of Pain arifes.

But when the Globules of the Blood cohere in Mafles too large, and will not eafily be fo feparated as to pafs freely through the

If the Diameter of one thoufand nine hundred and forty Blood-Globules be equal to the Length of one Inch ; and it,nbsp;as Geometricians demonftrate, Spheres be to each other as thenbsp;Cubes of their Diameters,,it muft neccffarily follow, that anbsp;Sphere whofe Axis is one Inch in Length muft be equal tonbsp;feven thoufand three hundred undone millions, three hundrednbsp;and eighty-four thoufand fuch Globules,

minutefl Veilels, the Force of the Fluid muft there be greater, and confequently unequal ;nbsp;the Refillance of the Solids muft alio benbsp;thereby increafed, and rendered likewife unequal : whence feme Diftemper muft arife.nbsp;If, on the other hand, the Globules arenbsp;broken, or feparated into fmaller Maffes thannbsp;the natural Standard Size, they will take upnbsp;more Room than they did before ; and, being crow'ded too abundantly into the capillarynbsp;Veffels, will occafion Dillenfion, Uneafinefs,nbsp;and perhaps a partial Stagnation there: whilft,nbsp;in the larger Veffels, the Current rolls alongnbsp;with too great Rapidity, the Force of thenbsp;Fluids, and the Refiftance of the Veffels, arenbsp;both rendered unequal, and the Balance be-tw'een the Solids and Fluids is entirely overturned. None of the Secretions in this Statenbsp;can duly be performed ; and unlefs fomenbsp;Means be found to reftore the Equilibrium,nbsp;the Event muft foon be fatal.

I believe it will be allowed, that where one Perfon dies from a Diforder in the containing Veffels, tw^enty mifearry by fome unnatural Alteration in the Fluids that pafsnbsp;through them: and therefore, if we can findnbsp;what their natural State is, the Means whereby it may be preferved in fuch State, bynbsp;what Accidents it may be prejudiced, andnbsp;how it may be reftored, our Pains will benbsp;well employed.

VoL. I. nbsp;nbsp;nbsp;Inbsp;nbsp;nbsp;nbsp;In

In order to obtain this ufeful Knowledge, it will be necelTary to examine the humannbsp;Blood and other Juices, frequently, with thenbsp;Microfcope, in every Condition, and undernbsp;every Diftemper, as well as in a State ofnbsp;Health : by which we flaall have ocular De-monftration of its different Appearanees innbsp;each State, and of the Changes it undergoes;nbsp;and by Experiments of various Mixtures withnbsp;it, may poflibly difcover by what Means itnbsp;can be altered from one Condition to another:nbsp;as from a thin and broken to a more firmnbsp;and confiftent State, and fo on the contrary.

Would our learned Phyficians, who are heft able to judge of fuch Matters, be induced to take this Method into their Pradlice, itnbsp;is reafonable to believe, that in a few Yearsnbsp;the Caufes of Difeafes would be better known,nbsp;and the Art of Healing brought to a muchnbsp;greater Certainty, than it is at prefent. Annbsp;Obfervation of Mr. Leeuwenhoek is verynbsp;well worth regarding: he took Notice, thatnbsp;when he was greatly difordered, the Globulesnbsp;of his Blood appeared hard and rigid, butnbsp;grew fofter and more pliable as his Healthnbsp;returned : whence he infers, that in annbsp;healthy Body it is requifite they fhould benbsp;foft and flexible, that they may be capablenbsp;of palling through the capillary Veins andnbsp;Arteries, by eafily changing their round Figures into Ovals, and alfo of re-alTumingnbsp;their former Roundnefs when they comenbsp;into VeiTels where they find larger Room.

Changes are produced in Fluids furprizing-ly and fuddenly, as a very few chemical Experiments will demonftrate : the Bite of Venomous Creatures, and Inoculating for the Small-Pox, �hew likewife how minute a Proportion of poifonous Matter will contaminate the whole Mafs of human Blood; whichnbsp;can no otherwife be effe�led but by alteringnbsp;the Solidity, Figure, Size, or Motion of itsnbsp;component Parts or Globules. And it is probable, that in many Cafes it may be changed from a morbid to a healthy State, bynbsp;Ways not lefs eafy, could we be fo happynbsp;as to find them out: for we cannot reafon-ably fuppofe, that the beneficent Author ofnbsp;Nature has given more certain and readynbsp;Means of doing Mifchief than of doing Good.

Many Diftempers might perhaps be cured by an immediate Admilfion of fome Medicine into the Veins, which elude the Powernbsp;of all that can be taken by the Mouth. Fornbsp;the Stomach, by its Heat, its Adtion, and anbsp;Mixture of its Juices, works fuch an Alteration in Things before they can be admittednbsp;into the Blood, that they are unable to produce the fame Effedts as if they were received into it fimply and unchanged.

Some Trials that have been made already may ferve in a great Meafure towards confirming the above Suppofition. Dr. Fabri-cius injedled with a S vphon into the Mediannbsp;Vein of a Soldier�s Right Arm, in die Hof-

pital at Dantzick about two Drams of a certain purgative Medicine, which in aboutnbsp;four Hours began to operate, and gave thenbsp;Patient five Stools. His Cafe was Venereal,nbsp;and in fo terrible a Manner, that there werenbsp;Nodes on the Bones of his Arm. But bynbsp;this fingle Injedlion, and without any othernbsp;Medicine, the Protuberances gradually dif-appeared, and the Difeafe was quite cured,nbsp;He likewife ipjedted into the Vein ol a married Woman, thirty-five Years old, and trou-:nbsp;bled from her Birth with Epileptic Fits, anbsp;fmall Qiiantity of a purging Rezin diffolvednbsp;in an Anti-Epileptic Spirit : this occafionednbsp;a few gentle Stools ; after w'hich the Fitsnbsp;were lels violent every Time than other, andnbsp;in a fliort Time returned no more at all.

Dr. Smith 'j~, of the fame Chy, injedted Alteratives into the Veins of three Patients inbsp;one was lame with the Gout, another exceedingly Apopledtic, the third alflidfed withnbsp;that ftrange Diftemper called the Plica Po-lonica; and they were all cured by the faidnbsp;Ipjedlions.

S.Fraoassati injedted Aqxia Forfis into the jugular and crural Veins of a Dog, whichnbsp;died immediately. The Blood was foundnbsp;fitted in the fmaller Veffels, and the largernbsp;Vefiels burfl. Whereupon he remarks, that

tire Blood, it may probably be cured by fomO Difolventnbsp;nbsp;nbsp;nbsp;�Another Dog, in whof�

Veins Oil of Vitriol was injected, corliplained a great while, foamed like Epileptics, breathed fliort, and died. His Blood was fixednbsp;�nd grumous, refernbiing Soot.�Oil of Tartar was injedled into a third Dogj whoj af^nbsp;ter much bemoaning, appeared fwelled, andnbsp;died. His Blood was not in the leaft curdled, but thinner and more florid than com-*nbsp;mon.�This proves too great a Separation,nbsp;as well as a Coagulation, mortal.

Mr. Boyle found, that by putting a little Aqua Fortis^ Oil of Vitriol, or Spirit of Salt,nbsp;into warm Blood, it did not only lofe itsnbsp;pure Colour and become dirty, but in anbsp;Moment was coagulated ; whereas urinousnbsp;Spirits abounding in volatile Salts, fuch asnbsp;Spirit of Sal Armoniac, mingled with it, didnbsp;not curdle it, or debafe its Colour, but madenbsp;it redder, kept it fluid, and preferved it anbsp;long while from Putrefaftion.

As the Microfcope has informed us of the StruBure of the Blood, which without itsnbsp;Plelp could never have been difcovered; andnbsp;as its continual Affiftance is needful to examine and diftinguifli minutely any Changesnbsp;that may be wrought therein, either for thenbsp;better or the worl'e, by Accident or by Medicine ; I hope this Difcourfe will not benbsp;judged too long or foreign to my Subjecft,

fince Hints of this Kind may prove highly beneficial to Mankind, if they Ihould be fonbsp;fortunate to fall into the Hands of thofenbsp;who are inclinable to purfue and improvenbsp;upon them.

I come now to defcribe the Manner of bringing the Blood to a ftridt. Examinationnbsp;before the Microfcope, and fhall offer fuchnbsp;Ways as I have myfelf experienced ; notnbsp;doubting but the Ingenious will contrivenbsp;otherSi aS they may find Occafion.

Take (with the Tip of a Feather, or a foft Hair Pencil) a fmall Drop ofnbsp;warm Blood immediately from the Vein :nbsp;fpread it, as thin as pofiible, on the cleareftnbsp;fingle Ifinglafs placed on a Slider on purpofe,nbsp;and apply it to the firfl; or fecond Magnifier :nbsp;the Globules will then be feen diftindlly, andnbsp;a little Pradtice will enable to form a Judgment of any Alteration that may happen innbsp;the Size, Figure, Colour, or Appearance ofnbsp;them. We may alfo examine the Blood extremely well, by taking up a little of it in anbsp;very fmall capillary Tube of the thinneftnbsp;Glafs, and then placing the Tube before thenbsp;Magnifier*

If a Drop of the fame Blood be diluted with warm Water, and applied in either ofnbsp;the aboveWays, fome of the larger Globulesnbsp;will appear more afunder, and a great manynbsp;of them will be feen divided into thefmallernbsp;ones which compofe them.

If fome of the fame Blood be mixed with a little warm Milk, feveral red unbrokennbsp;Globules will be feen diftindlly j but thofenbsp;that are again feparated into their fmallernbsp;ones will be confounded with the Milk it-felf, of which the greateft Part is nothingnbsp;elfe but Heaps of fuch like-lized minutenbsp;Globules.

If we defire to try by Experiment what Alteration any Liquor, either poifonous ornbsp;medicinal, can produce on the Contexturenbsp;of the Blood, the Liquor Ihould be blendednbsp;with it at the very Inftant of its iffuing fromnbsp;the Vein : for if the Blood be in the leall:nbsp;coagulated before fuch Mixture, no certainnbsp;Conclilfions can be formed. Putting theVef-fel into which we receive it into a Bafon ofnbsp;Water a little hotter than the Blood, willnbsp;preferve it longer fluid, and make our Experiment by any Mixture with it fucceed thenbsp;better.�I would alfo advife, to get yournbsp;Inftrument in perfedl Readinefs, by adjuft-ing the Magnifier before the Vein is opened;nbsp;and likewife to make your Obfervations in anbsp;warm Place, left the Blood become congealed before you can finifti your Enquiry.

I 4 nbsp;nbsp;nbsp;In

In all Enquiries of Confequence, it is bcft to draw the Blood from a large Vein : be-caufe what we can gain (by the Prick of anbsp;Pin or Needle) from the Finger, or any fuchnbsp;Part, iffues from fome extremely minutenbsp;capillary Veffels only, and perhaps is not fonbsp;good a Sample of the Contexture of thenbsp;whole Mafs. Some Trials on both maynbsp;however not be amifs, to difeover whatnbsp;Difference there is between them.

By mingling with the Blood the leaft imaginable Quantity of t\\Qpoifonons Juice which iffues from the Teeth of a Viper when enraged, or from any other Animal, Vegetable,nbsp;or Mineral, we lliall difeover its immediatenbsp;Effedl upon the Globules ; and by confider-ing that the Alteration we obferve is wroughtnbsp;in it tho� at Reft, we fliall be able to judgenbsp;and calculate what Confequences muft enfuenbsp;from fuch a Mixture with the Blood, as itnbsp;circulates through the Veins of a livingnbsp;Creature.

lyir. William Cowper, examining a Solution of Opium with th.amp; MicroJ�cope, foundnbsp;its diftblved Particles in the Shape of fringednbsp;Globules : whence he concludes, that fuchnbsp;Particles circulating in the Mafs of Blood,nbsp;may be fo entangled in its Serum, or thickennbsp;it in fuch a Manner, as to retard its Velocitynbsp;when over-violent, and render its Motionnbsp;calm and equal; whereby all painful Senfa-

tions

tions will be taken off. And from the fame Principles it is eafy to account for all itsnbsp;other Effedls, aTid perceive how too great anbsp;Number of fuch fringed Globules muff caufenbsp;a total Stagnation of the Blood, and confe-quently kill. Vid. Philof.Tiranf. Numb. 222.

Spirits, Oils, diffohed Salts, Pindlures, Ef- � fences, and all other chemical Preparations,nbsp;furnifla us with numberlefs Subjects of Experiment ; and are certainly capable of producing the moff fudden and amazing Effects either good or bad, if injedled into thenbsp;Blood-Veffels of living Animals : the Caufesnbsp;of which Effects may in a great Degree benbsp;difcovered and accounted for, by mifcrofco-pical Obfervations on Mixtures of them withnbsp;the Blood when extracted from the Veins.

A little Blood being mixed with about four Times its Quantity of ¹ Sal Volatilenbsp;Oleofum, and viewed through a Microfcope,nbsp;there appeared an immediate Separation ofnbsp;the Globules. In about the eighth Part ofnbsp;a Minute fome of them were much dimi-nifhed, and in a Quarter of a Minute manynbsp;of them were much diffolved, and entirelynbsp;difappeared. Sometimes twenty Globulesnbsp;were feen near together, which foon leffenednbsp;to eighteen, then to fixteen, and becamenbsp;fewer and fewer, till only two o,r three werenbsp;left. Whence it is probable that Sal p^o-

latik Oleofum taken with the Food, and fo carried into the Lacfteals and Blood-Veflels,nbsp;may retain its Power of preventing fuch Coagulations as would otherwife happen.

T he Urine, Saliva, Semen, Sweat, Faces Alvi, and all other Animal Juices, are like-wife Objedls for the Microicope, to be examined either alone, or mixed with thenbsp;aforefaid Liquors : whence much ufefulnbsp;Knowledge may be acquired.

As to Colour in the Blood, a Blacknefs arifes in it from a Deficiency of Serum, asnbsp;Palenefs does from too great an Abundancenbsp;of it: for it will be always found, that whennbsp;Globules cohere together in too great Numbers they give a black Appearance. Whennbsp;this therefore is the Cafe, Means of dilutingnbsp;fliould be found out and made ufe of; fincenbsp;it is abfolutely requifite to Health, that thenbsp;Globules of the Blood Ihould float in a duenbsp;Qiiantity of Scrum, and be thereby circulatednbsp;freely through the minutefl: Veflels ; a contrary State to which has proved the Death ofnbsp;thoufands. � Mr. Leeuwenhoek tells us,nbsp;that whenever he found his Blood too deepnbsp;coloured, his Way was to drink four Di/hesnbsp;of Coffee in a Morning, in the room of hisnbsp;ufual two ; and fix Dilhes of in the Afternoon, inftead of three. He drank it as hotnbsp;as poflible, and went on in this Manner tillnbsp;he perceived his Blood grow paler, and con-fequently its Globules farther feparated.

CHAP. IX.

IN order to view the Blood circulating through its VeJJ'els, we muft make ufe ofnbsp;fuch /mail Creatures as by their Tranfpa-rency permit us to look within them, andnbsp;fee what paffes there : for, in a Man, or anynbsp;of the large Animals, the Skin is fo opakenbsp;that we cannot difcern even the fine Blood-Veffels themfelves, and much lefs the Current that runs along them. Our Information, however, will not be greatly different;nbsp;for the whole Animal Creation is eftablifliednbsp;on one and the fame Plan, and the Circulations in the meaneft living Creature arenbsp;carried on through Veffcls of a like Strudlurenbsp;(in the general), and are accelerated or retarded by the fame Caufes, as in the nobleff.

And, in Truth, as to the Circulations of the Fluids, and the Motions of the Bowels,nbsp;the Brain, or any of the internal Parts,nbsp;more Knowledge may be gained by infpedt-ing InfeBs and fmall Animals with the Mi~nbsp;crofeope, than by the moft Ikilful and curiousnbsp;Diffedions, or anatomical Experiments onnbsp;larger Subjeds. For the Skins of fome ofnbsp;thefe little Creatures are fo tranfparent, thatnbsp;we may fee plainly through them the Ordernbsp;and Difpofition of the Veffels underneath

and the Coats of thefe Veflels are, again, of* fuch an amazing Thinnefs and Delicacy ofnbsp;Contexture, that they are little or no Impediment to our View of the fecret, tho* regular, Operations of Nature, and the Lawsnbsp;file adts by when undifturbed and quiet jnbsp;whereas our DifTeftions of larger Animals,nbsp;while alive, mayfhew her at work, indeed,nbsp;but in fuch Confufion, by our breaking innbsp;upon her violently, that all her Motions thennbsp;muft be in great Diforder, and confequentlynbsp;uncapable of affording any fatisfadlory Information as to the Circulations.

In this Sort of Creatures too, after viewing as long as we think fit the natural'and regular Current of the Blood, as it is carriednbsp;on in a State of Health we may, by Pref*nbsp;fure, and feveral other Ways, impede, dif-turb, and divert its Courfe; and may findnbsp;Means, by various Mixtures with it, of inducing a morbid State; and at laft, by letting the Creature die before our Glafs, wenbsp;may perceive all the Changes it undergoes,nbsp;and what occafions the intermitting, vibrating, trembling Pulfe of expiring People.

In feveral of thefe little Creatures we can not only fee the general Courfe of the Blood,nbsp;but are able perfectly to diftinguifh thenbsp;Figure and Circumftances of the Globulesnbsp;whereof it is compounded, and the Alterations they fuffer when they pafs out of thenbsp;larger into the more minute Veflels� For

roany of theVeflels are fo fmall, that even lingle Globules cannot poffibly find aPafiagenbsp;thro� them without being comprefied intonbsp;oval Shapes : and yet thefe VefiTels are largenbsp;in Compariion of the finefi: Veffels of all, tonbsp;pafs through which, the Globules mull: benbsp;divided and fubdivided into their frnallefi:nbsp;and moll: minute component Globules,

It is amazing to. oblerve how careful Providence has been to prevent the Bloodnbsp;from coagulating, or cohering in Mafies dangerous to Life, by the very Difpofition ofnbsp;the Veffels it runs through : which, whethernbsp;feparating or uniting, are fo contrived as tonbsp;caule the Globules to come frequently together with a brilk Collifion, or ftrikingnbsp;againfi ea Ji other. The ^rteries^ for Example, which convey the Blood from thenbsp;Heart to the Extremities of the Animal,nbsp;and in their Progrcis continually leflen theifnbsp;Diameters, and divide into fmaller Branchesnbsp;almofi: ad infinitum �, in thefe Arteries, Inbsp;fay, at every fuch Divifion, many of thenbsp;Globules of the Blood mull rufh, with anbsp;cpnfiderable force, againft an Angle diredl-ly in their Way; whence recoiling back onnbsp;thole immediately behind, they muft llrikenbsp;upon one another, and caufe a Kind ofnbsp;Commotion, ere the Current can dividenbsp;readily into the two fmaller Branches. Seenbsp;Fig, III. Plate X.-In the Veins, which.

on the contrary, return back the Blood from the Extremities to the Heart, whofe Diameters enlarge as the Tide rolls along, andnbsp;whofe fmall Branches are continually uniting and making larger Veffels, till at laft allnbsp;their Streams fall into one ; here, at everynbsp;Conjundlion of two Branches, their Currents rufh againft each other with Violence :nbsp;by which Concuffion unnatural Cohefionsnbsp;are broken or prevented 3 and of this thenbsp;Microfeope can afford us ocular Demonftra-tion. Vide Fig. IV.

By the Current of the Blood, I mean its f reaming or p fing on either from ornbsp;towards Heart, through znyVef 'el, whether it be a Vein or Artery.

By the Circulation I would be underflood to intend, the Courje or Current oi \t, fromnbsp;the Heart, along the Arteries, to th.e Extremities of the Body: together with its Returnnbsp;by the Veins from the Extremities back againnbsp;towards the Heart.

Both thefe the Microfeope can bring to View 3 but the latter is fomewhat more difficult

ficult to be aflured of than the former j for when the Veffels before us are extremelynbsp;fmall, it is not always eafy to diftinguilhnbsp;which of them are Veins and which arenbsp;Arteries.

The larger Arteries are indeed diftinguifh-able by a Protrufion of the Blood at each Contra�lion of the Heart, then a Stop, andnbsp;then a new Protrufion, which may plainlynbsp;be feen continually fucceeding one another:nbsp;whereas the Current paffes through thenbsp;Veins with an equal and unintermittingnbsp;Stream. But in the more fine and extremenbsp;Branches of the Arteries this Difference isnbsp;not perceivable.

The tranfparent Membrane between a Frog�s hind-foot Toes is the Obje�t mofl:nbsp;commonly employed for viewing the Currentnbsp;and Circulation of the Blood; and in this, ifnbsp;well expanded, it may be feen fairly and dif-tinftly, both in the Veins and Arteries, innbsp;the Manner reprefented Plate XI. Fig. I,

E. nbsp;nbsp;nbsp;E. E. Arteries and Veins in the finenbsp;Membrane, with the Blood-Globules circulating through them.

The Way of applying it to the Microfeope was deferibed Page 13, and therefore needsnbsp;not be repeated here.

The Tails or Fins of fmall FiHies may likewife be ufed very commodioufly to thisnbsp;Purpofe, and prefent to view great Numbers of Veins and Arteries with the Bloodnbsp;paffing different Ways through them.

It is difficult here in LoJidon to meet with any Fiffies alive and proper for this Infpec-tion, except E.els and Flowtders ; either ofnbsp;thefe however will ferve exceeding well;

your Eel into a Glafs Tube filled with Water, after wiping off its Slime, which would ob-feure your Glafs. Then having floppednbsp;both Ends, to prevent the Water�s runningnbsp;out, apply the Tail or Fin to your Microfeope, and you will fee the Circulation in anbsp;very agreeable Manner. If you put notnbsp;Water in your Tube, the Sliminefs of thenbsp;Eel will immediately foul the Glafs andnbsp;prevent your Pleafure,

The flat Figure of the Flounder will not permit us to put it into a Tube as we do thenbsp;Eel, or view it by every Kind of Microfeope : but if a plain Piece of thin Glafs benbsp;placed over the Hole where Objects are applied to the Double Refiedling Microfeope,nbsp;its Tail may be fpread advantageoufly uponnbsp;the faid Glafs : and by fetting a Book, ornbsp;7nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;lome-

foiiiething elfe of a proper Fleightto fupport the Body of the Fifli, it will lie in a verynbsp;good Pofition for View, and the Circulationnbsp;may be feen diftin�lly.

Eels and Flounders live a long While out of Water, and are therefore inoft ufeful fornbsp;this Service here at London-, biit in thenbsp;Country many Sorts of other fmall Fifhesnbsp;may be found much more tranfparent.

Mr. Leeuwenhoek informs us that he faw, with great Admiration, in the ut-moft Extremities of a very minute p'ifh�snbsp;Tail, how the larger Arteries were there divided into the moil fine or evanefcent ones jnbsp;and that many of the fmaUeil Veins, returning from the faid Extren ities, met together at lafi: in fome larger Vein. Therenbsp;appeared alfo in fome Veflels fuch an Agitation of that Blood (which was protrudednbsp;from the larger Arteries towards the evanefcent ones at the very Extremity of thenbsp;Tail, and returned afterwards through manynbsp;minute Veins into a large one) as hardlynbsp;can be conceived. In the larger Arteries henbsp;could perceive a continual newProtrufion, ornbsp;Acceleration of the Blood�s Courfe receivednbsp;from the Heart; but in the fmaller Arteriesnbsp;the Motion feemed equable vvithout any

fuch repeated Propulfion; and though in the minutetl Veffels there appeared no Colour,nbsp;yet in the larger Vein or Artery, thoughnbsp;near the End of the Tail, the Blood wasnbsp;plainly red.

We cannot properly call any Veflel an Artery farther than the Pulfatiqn reaches^nbsp;beyond that, and returning towards thenbsp;Heart, it mull be accounted a Vein: fornbsp;Veins are only Arteries elongated; but asnbsp;they frequently divide into Branches thatnbsp;evade Difcovery, it is, perhaps, impoffiblenbsp;to determine exactly where the Arterie*nbsp;end, and where the Veins begin.

They do not always, however, branch out fo extremely fine before their Inofcula-tion or Communication with the Veins; fornbsp;the fame curious Obferver tells us, that onnbsp;each Side the little Griftles, which gave anbsp;Stifihefs to the Tail of the Fi�h abovemen-tioned, he could fee a very open Communication of the Veins and Arteries; the Bloodnbsp;running towards the Extremities throughnbsp;Arteries, and returning back again throughnbsp;Veins that were evidently a Continuation ofnbsp;thofe Arteries, and of the fame Diameternbsp;with them : And this he faw in thirty-fournbsp;different Places, in as many Arteries, and asnbsp;many Veins. The Manner whereof, as bynbsp;him d(jlineated, is ihewn. Tab. XI. Fig. II.

A; A. reprefentamp; two Arteries, one of which runs on each Side of a minute Grifile.

As this whole Fiihwas riot half an Inch in Length, how fmall muft the Tail thereofnbsp;be, in which, notwithftanding, the Circulation of the Blood was vifible in thirty-fournbsp;Places, and the Current of it in fixty-eightnbsp;Veflels ! and yet thefe Veffels were very farnbsp;from being the moft minute of all. Hownbsp;inconceivable then muft be the Number ofnbsp;its Circulations in an human Body! Nornbsp;need we wonder to behold it iffuing forthnbsp;at every Prick of a Pin or Needle. Uponnbsp;confidering this, Mr. LeeuWeI^hoeR: adds,nbsp;that he is fully perfuaded, a thoufand different Circulations of the Blood are continually carried round in every Part of a Maii�gnbsp;Body that is not larger than the Breadth ofnbsp;his Fore-finger Nail

The Tail of a Newt, or Water-Lizard, applied in a Glafs Tube, after the Mannernbsp;diredted for the Eel, affords an entertainingnbsp;Profpeft of the Circulation through Numbers of fmall Veffels. But nothing can fhewnbsp;it finer than an exceeding fmall Newt -f- of

this Water-Kind, which fometimes may be found lefs than an Inch long, and fo tranfpa-rent, that the Blood may be feen running innbsp;all Diredions, not only through the Vedelsnbsp;of the Tail, but throughout the whole Body:nbsp;And it is particularly delightful, to behold, innbsp;the little Toes, the Stream thereof runningnbsp;to the Extremity in one, Channel, and returning, back again by another.. Juft below thenbsp;Head are on either Side three Fins, or fome-what like Fins, which, in fwimming, thenbsp;Creature makes ufe of to pcife and guide itsnbsp;Body : each of thefe appears by the Micro-fcope divided, likeinto many pointed Branches : in ,any one whereof, as in,.the.nbsp;Toes, ,the Blood is feen coming along an Artery to the Extremity, and then immediately returning towards the Heart againnbsp;through a Vein that lies parallel, and almoftnbsp;clofe thereto, and with which its Communication is very apparent.-�As thirty or fortynbsp;of thefe Branchings prefent themfelves before the Eye fometimes at once, with thenbsp;Blood diftinftly circulating in all, theyaftordnbsp;a charming Sight: and they may be viewednbsp;by the third or fourth Magnifier ; for thenbsp;Globules of the Blood in Newts are largernbsp;than in any other Creature I have examined,nbsp;and are fewer in Proportion to the Serum ornbsp;Water they float along in. To which I maynbsp;alfo add, that the Figure of them, as they are

In Spring-time, if alittleFrog�r Spawnhc kept fome Days in a fmall Quantity of thenbsp;Ditch-Water wher'ein you found it, you willnbsp;be furnhhed with a Number of exceedinglynbsp;fmall T'adpoles, which, when firft they be-,nbsp;gin to fwim, are almoft wholly tranfparent;nbsp;and if placed before the Micrafcope, in anbsp;Tube proportionably fmall, with fome Waternbsp;in it, you will eafily difcern the Heart and itsnbsp;Pulfation, together with the Blood circulating in every Part of the Body; and,.particularly, in the Tail more than fifty VelTelsnbsp;preient themfelves at one View.

Thefe T^adpoles become lefs clear every Hour, and in a Day or two their Skin growsnbsp;fo opake that the Circulation of the Bloodnbsp;can be feen no longer, unlefs it be in thenbsp;Tail, or better fiill in the Fins, at the joining-on of the Head^

A fmall Mufcle taken carefully from its Shell, and placed before the Microfcope onnbsp;an Ifinglafs, affords a View of many Arteriesnbsp;and Veins, through which the Circulationnbsp;of the Blood may be very clearly feen : andnbsp;one great Advantage in this Objedl is, thatnbsp;it lies always quiet ; whereas moft othernbsp;Creatures are difficult to be kept ftill longnbsp;enough for Obfervation. The Motion of the

Blood continues in it fix or feven Hours with little Alteration ; and, by moiflening it nownbsp;and then with fait Water, ruay probably benbsp;continued much longer.

I can alfo allure you, from my own repeated Experiments, that if a large Mujcle be carefully opened, and a Piece of the thinnbsp;tranfparent Membrane eafy to be found therein be Inipped olf with a Pair of fharp ScilTars,nbsp;and applied to the Microfcope, the Blood willnbsp;be feen paffing through Numbers of Veinsnbsp;and Arteries gt; and if the Extremity of thenbsp;Membrane be viewed, the true Circulation,nbsp;or the Return of the Blood from the Arteries through the Veins, will be Ihewn in anbsp;delightful and fatisfaftory Manner, and continue for a long Time. There are likewifenbsp;other tranfpareqt Parts of the Mujcle, wherenbsp;the Paflage of the Blood is yery difcernible :nbsp;and as Mufcles are to be got mod: Times ofnbsp;the Year in London, the Knowledge hereof^nbsp;will, I hope, oblige the curious.

We are told by Mr. Leeuwenhoek, that in the fartheft Joints of the hinder Legsnbsp;of little Crabs'^, he beheld the Blood circulate through the Arteries and Veins withnbsp;greater Rapidity than he had ever obferved itnbsp;in any other Creature; and, moreover, thatnbsp;the red Globules thereof were twenty-five

Times fewer in Proportion to its Serum than in any other Land or Water-Animal henbsp;had ever before examined.

At the proper Time of Year, exceeding fmall Crabs may be found in great Abundance, under Stones and Brick-bats, on thenbsp;Shore of the River T^hanies, when the Tidenbsp;is out: and as many of them are no largernbsp;than a YitiltSpider, it is highly probable fuchnbsp;may be tranfparent in many Places of thenbsp;Limbs and Body j notwithilanding Mnnbsp;Leeuwenhoek found his, which were annbsp;Inch broad, opake every where but in thenbsp;extremeft Joints of the hinder Legs. Perhaps too they may appear more tranfparentnbsp;if they are applied to the Microfcope in anbsp;little Tube filled with Water, than if theynbsp;are viewed dry : for it is obfervable, thatnbsp;many Objedls acquire a Tranfparency by being wetted, in the fame Manner as Papernbsp;becomes clear by being rubbed wnth Oil.

The Blood may be feen circulating in the Legs and Tails o� Shrimps, efpecially if viewed in Water; but then the Water mufi:nbsp;have a little Salt put thereto, or elfe theynbsp;will foon expire. In Shrimps the Blood isnbsp;not red ; which has given Occafion to callnbsp;them, as well as many other Infects, exanguesynbsp;or bloodlefs : tho� in reality no living Creature is without Blood; for animal Life con-lifts in a Circulation of fome Fluid through

Arteries and Veins; and that Fluid, what-e\'er Colour it may be of, is properly to be accounted Blood. In Grafshoppers the Globules (which may be feen palling throughnbsp;the Vedels in their Wings) arc green ; andnbsp;yet I am apt to think. Nobody that viewsnbsp;them will hedtate to call thetp, with thenbsp;Serum vyherein they fwim. Blood.

In the traufparent Legs and Feet of feve-ral fmall Spiders, the Current of the Blood may plainly be didinguidied both in thenbsp;Veins and Arteries; alio in the Legs of verynbsp;XxxxdSXPunices or Bugs xX. is remarkably vidble,nbsp;together with an extraordinary Vibrationnbsp;of the VelFels, which I never have obferv-ed in any other Creature. In thefe too, ifnbsp;clear, as they may fometimes be found, thenbsp;Wonderful Motions of all the internal Partsnbsp;will afford an agreeable Entertainment tonbsp;the curious, and may be examined as longnbsp;and as often as they pleafe. For I have keptnbsp;a Bug alive, in a Slider between two Piecesnbsp;of Ifinglafs, at lead fix Weeks together, not-withftanding it was confined fo clofe as tonbsp;be uncapable of fiirring : and altho� duringnbsp;that Time it often feeined dead and motion-Jefs,when I placed it before the Microfeope,nbsp;a little V/armth would fet the Bowels atnbsp;Work again, and renew the Current of thenbsp;JBlood as brillcly as ever.

After

After many Obfervations made by Mr. Le EUWENHOEK On the Blood of Cocks, Spar-rows. Frogs, �Trouts, Perch, Cod, Salmon, amp;c.nbsp;he affirms, that the red Particles in thenbsp;Blood of Birds, Fijhes, and Water-Animals,nbsp;are conftantly * flat and of an oval Figure;nbsp;that is, they are longer than their Breadth,nbsp;and appear as in Plate X. Fig. V. The fe-rous Part of the Blood in Fijhes and Aquaticnbsp;Animals is alfo greatly more, in Proportionnbsp;to the red Particles, than it is in Beajts ornbsp;Men, and the Particles themfelves are larger;nbsp;fo that, by being bigger, and fwimming farther afunder, they may he feen much better,

Mr. Leeuwenhoek obferved the Blood circulating in the filmy Wings of a Bat �j*,nbsp;and likcwife in its Ears, and found the Globules thereof perfedlly round : wherefore;nbsp;allowing his AfTertion, that in Fiffies andnbsp;Birds they are always flat and oval, we neednbsp;no longer hefitate how to clafs this oddnbsp;Creature; but, notwithftanding its flying,nbsp;fhall pronounce it to be a Beaji.

He tells us, that Bats can fee as well by Day as Night: but he fuppofcs the Heatnbsp;and Drynefs of the Day-Air would flirivelnbsp;up the thin Membranes of their Wings, andnbsp;confequently flop the Circulations there;

f Arc. Nat. Tom. I. Part II. p. 51. Again, Tom. II. Epill. iz8. Again, Tom. IV. Epift. 65.nbsp;i Arc. Nat. Tom. IV. Epift. 67.

whereas the cool Dews of the Evening render them moift and pliable; which makes them chufe that Time to come abroad.

In viewing fex^eral of the Obje(5ts here mentioned, one iball often obferve the Bloodnbsp;palling through Velfels fo minute, that thenbsp;Globules of it cannot glide along other wifenbsp;than angle, and fqueezed into oblong Forms:nbsp;yet an hundred of the red Globules of fuchnbsp;Blood, if placed clofe to one another in anbsp;Row, would not equal the Length of thenbsp;Diameter of a large Grain of Sand; andnbsp;confequently a Million of them exceeds notnbsp;a Grain gf Sand in Bignefs

The Effects of Heat and Cold upon the Blood are well worth taking Notice of: fornbsp;as Heat relaxes the Velfels, the Blood findsnbsp;more Room to move in, its Globules float atnbsp;greater Diftances, and it circulates morenbsp;freely; whereas Cold fo contradls the Vef-fels, that the Globules are comprefl; together, and the Blood is impeded, and in fom�nbsp;Degree coagulated in the minute Capillarynbsp;Veins and Arteries of the extreme Parts ; asnbsp;is evident from the Swelling and Blacknefsnbsp;of the Hands and Feet when expofed to fe-vere Cold.

6 nbsp;nbsp;nbsp;Before

Before I clofe this Chapter, I fliall briefly f:omiTmnicate fome Experiments I had thenbsp;Pleafure of making lafl: Summer, with mynbsp;jnofl: ingenious and valuable Friend Do�tornbsp;Alexander Stuart, Phyfician to her latenbsp;Majefly, in order to view the Circulation ofnbsp;the Blood by the Solar or Camera Obfcuranbsp;Microfcope, which has the Advantage ofnbsp;magnifying Objefts beyond any other Sortnbsp;of Microfcope j but mufl; refer the Curiousnbsp;to a more full Account thereof laid by thisnbsp;Gentleman before the Royal Societyy 'andnbsp;which will be publilhed in the Philofophicalnbsp;Pranfaciions.

1 mufl; firfl defcribe a particular Apparatus, invented by the DoBor for examining thenbsp;Circulation of the Blood in Frogs, Mice,nbsp;Bats, or any Creatures of the like Size. Innbsp;this Contrivance the Looking-glafs, Tube,nbsp;and convex Lens are juft the fame, andnbsp;placed in the Hole of a Window-fliutter innbsp;the fame Manner, as defcribed Page 22. Butnbsp;here, inflead of ufing Wilson�s \itt\c Pocketnbsp;Microfcope, he has got the Belly-part of anbsp;large Refleding one fixed horizontally on anbsp;Pedeftal, at a Height exadly equal to thenbsp;Tube. This flands on a little Shelf madenbsp;to fupport it j and to the Snout thereof,nbsp;wdiich lies on a Level with the Tube, thenbsp;Magnifiers are fcrewed. The Objed, beingnbsp;extended and faftened with Strings and Pinsnbsp;on a Frame convenient for the Pyrpofe, is

applied between the Tube and the Magnifier �, whereby the Sun�s Rays reflected from the Looking-glafs, through the Tube, uponnbsp;the Obje�l, pals on through the Magnifier,nbsp;and exhibit upon the Screen an Image of thenbsp;Objedl moR prodigioully enlarged. This, Inbsp;hope, may .give fome Idea of our Inftrumcnt;nbsp;and now I come to the Application.

Our Objedt was a �rog, whole Limbs being extended and faftened on the Frame,nbsp;we opened the Skin of the Belly from nearnbsp;the Anus to the Throat j then giving it anbsp;little Snip fideways both at the Top andnbsp;Bottom, by Ricking a Fifj-Hook in eachnbsp;Corner of the Skin, it was ealily Rretchednbsp;out before the Microfcope, and prefented onnbsp;the Screen a moR beautiful Pidlure of thenbsp;Veins and Arteries in the Skin, with thenbsp;Blood circulating through them. In thenbsp;Arteries we could plainly perceive the Bloodnbsp;flopping, and as it were receding a little, atnbsp;each Dilation of the Heart, and then immediately rufliing forwards again at eachnbsp;Contraction whilR in the Veins it rollednbsp;on in a continual Current with inexprelhblenbsp;Rapidity

� When the Arteries were magnified very much, by removing the Screen to a confiderable Diftance, the alternate �xpanfion and Contraflicn of their Sides were very vifiblcnbsp;and remarkable. -

and extending the Mufcles before the Micro-Jcopc, by the fame Means as we had done the Skin, we had the Pleafure of viewing theirnbsp;Structure, which jWe found to CQnfid; ofnbsp;Bundles of tranfparent Strings qr Eibres,nbsp;lying parallel to qne another, and joinednbsp;together by a common MembranCi^^.'Pfefenbsp;Strings or Fibres appeared through; ^heirnbsp;whole Length made up,pf niinute roundifhnbsp;yefcles, pr, in other, Words, feemedjUkenbsp;Rulhes divided the long Way. We couldnbsp;not be certain of any Circulation throughnbsp;ijhe Mwfcles, though fometimes, we imaginednbsp;we faw� a very flow Motion of fame tranfparent Fluid : but the Objedl growing drynbsp;and rig.id^ obliged us to leave that Enquirynbsp;to a farther examination.

We then proceeded to our lafl: Experiment, which was to draw out gently a Part of the Frog�s Gut, in order.to apply the Me-fentery to the Microjeope: � olx\A h.Qxe.m wenbsp;fucceeded fo happily, that I believe the Circulation of the Blood was never before feenrnbsp;in fo diftin�l and fine a Manner. No Words:nbsp;can deferibe the wonderful Scene that wasnbsp;prefented before- our Eyes ! We beheld thenbsp;Blood pafling through numberlefs Veflels atnbsp;one and the fame Inflant, in fome one Way,nbsp;in others the quite contrary. Several of thenbsp;VcflTcls were magnified to above an Inch innbsp;Diameter, .and the Globules of the Bloodnbsp;rolling through them feemed near as large as

Pepper-Corns j whilrt in many of the mi-nuteft Veffels only Angle Globules were able to find a Paffage, and that too not withoutnbsp;changing their Figure into that of oblongnbsp;Spheroids. We faw here, like wife, muchnbsp;better than we had done before, the Pulfa-tion and Acceleration of the Blood in thenbsp;Arteries, in the Manner before defcribed,nbsp;and could clearly diftinguifh two or threenbsp;Veflels lying over one another, with Currents running different Ways. In fhort, itnbsp;appeared like a beauteous Landfeape, wherenbsp;Rivers, Streams, and Rills of Running Waternbsp;are every where difperfed.

During this Examination, we took notice of a Veffel extremely minute, ilfuing fromnbsp;the Side of a larger, and turning backwardsnbsp;from it in a curve Line. We perceived, atnbsp;unequal Intervals, fometimes one, fometimesnbsp;two, and fometimes three colourlefs Globules dropt or fqueezed out of the largernbsp;Veffels into this minute one, and glidingnbsp;through it lingly and very flowly; whichnbsp;made the Doctor imagine it might be a fe-cretory DuB. We obTerved, likewife, thatnbsp;as the Animal grew languid and near expiring, the Blood in the Arteries would flopnbsp;on a fudden, feem as it were coagulating,nbsp;and then run backwards for fome Time}nbsp;after which it would again recover its natural Courfe with a great deal of Rapidity.nbsp;^A due Confidcration of thefc Appearances

liiight poffibly account for the Intermiffions, Starts, and Irregularities in the Pulfe of Per�nbsp;Ions near the Poi4t of Death.

TH is wonderful Phsenomenon may be feen diftindlly in feveral fmall Infe�ls,nbsp;fomc whereof I lhall here mention, withnbsp;fhort Directions how to find it.

Divide a Bee particularly an Humble^ Bee, near the Neck j and its Heart, whichnbsp;is a white pulfing Particle, may be feeanbsp;beating brifkly.

The Head of the HorferFly being cut off, juft at the fetting-on of the Neck, a littlenbsp;Particle (which is the Heart] will appearnbsp;with a Fulfation in it for half an Hour.

The Grafshopper :}: has a green Film or Plate over its Neck and Shoulders, whichnbsp;being raifed with a Pin, its Heart may benbsp;feen beating very orderly for a long Whilenbsp;together.

Cut off the Head of that little flying Beetle, kpown to every Child by the Name of Lady-Bird^, or Cow-Lady; ereCl. it per-

� Dr. Power�s Microfcop. Ob/ernjat. p. 4 t Ibid. p. 34.nbsp;nbsp;nbsp;nbsp;II Ibid. p. 30.

pendicularly, and y�u will � fee two -fmali black Eyes, each iet between three whitenbsp;Plates like politlied -Ivory, on one Side twonbsp;fmall ones, and a large one on the other.nbsp;F^ll off both 'the truftacFous and �filmy'nbsp;Wings which cover a tender black Skin,nbsp;and removing that Skin, the Pulfation of thenbsp;Heart may^-be^fech beating vigoroufly fornbsp;twelve or fourteen Hours.

' Hht'H�art z Snaii^to be found ex-adlly againft the rouildPfole near its NeCk, of a white Colour, and� -may be fe�n beatingnbsp;a Charter of an Hour after Difiedlion -f*.

� it may -alfo be fe�n- in a Loufe, as ! fhall fliew when I come to deferibe that Creature jnbsp;and I make no doubt the curious and diligent Enquirer will be able to diffovqr ft innbsp;Multitudes of other little Animals,

Tho perijialtic Motio?i of the Stomach and Bowels may be fecn very diftiniftly m Lice,nbsp;Gnats, Flies, amp;c. and a Multitude of othernbsp;Infedts.nbsp;nbsp;nbsp;nbsp;^nbsp;nbsp;nbsp;nbsp;.

* Power�s Mkrofcop. OL/er^jat. p. 36. t Swammerd. Hijt, Citnrrele des InJeQes, p. 77.

CHAP.

[ ^39 ]

TH E flejhy Fibres of the' Mufcles (according to the Obfervations of Mon-feur Muys) are compofed of other fmaller Fibres or Fibrils, the Size of a flender Hair;nbsp;five or fix hundred of which Fibrils go tonbsp;the making up of one flefy Fibre, whofcnbsp;Diameter is no more than the twenty-fourthnbsp;Part of an Inch. Each of thefe Fibrils isnbsp;again compofed of more than three hundrednbsp;fmall tranfparent Fubuli, fo extremely fender, that were one of thofe Blood-Globulesnbsp;(which Mr. Leeuwenhoek fuppofes butnbsp;the millionth Part of a Grain of Sand) divided into twenty-four Parts, even thefenbsp;minute Parts could hardly enter and pafsnbsp;through fuch exceedingly fmall Tubes. Andnbsp;yet, that they do enter and pafs throughnbsp;them, is evident by the Rednefs of the Flefiinbsp;of Animals. We mull; therefore infer, thatnbsp;the Fiibuli forming a Fibril are really hollow ; that the Extremities of the Arteriesnbsp;open into them, and empty there a Part ofnbsp;their Liquor, which is carried back again bynbsp;the Veins to the Heart and that the Globules of the Blood are, for this Purpofe,nbsp;divided into Parts inconceivably fmall'¹.

Mr. Leeuwenhoek fays, each Mufcular Fibre is compofed of many fmaller Filamentsnbsp;or Fibrils; which, however minutCj he couldnbsp;plainly diftinguilh to be vafcular; for, if henbsp;cut acrofs their Length, the Light appearednbsp;through the Mouths of the Velfels; but ifnbsp;he cut them ever fo little obliquely, no Lightnbsp;was to be feen *. He found alfo, that eachnbsp;Fibril is invefted with a -f- minute Membrane, which is only a Congeries of Blood-Veffels, conveying Juices and Nourilhmentnbsp;thereto, though their Finenefs renders themnbsp;invifible. It is not, however, to be imagined, that each Fibril has its peculiar Membrane : but that all the Membranes togethernbsp;are like a Net finely fpread, with a Fibrilnbsp;ifluing through each of its Melhes.

This Strufture of the Fibres he obferved in the Flelh of an Ox and of a Whale j butnbsp;more plainly in that of a Whale, the Beef-Fibres lying more compadl and clofe. Henbsp;alfo found that the Fibres of a Moufe werenbsp;of the fame Thicknefs as thofe of an Ox,nbsp;though thirty thoufand Mice are not equalnbsp;to one Ox in Bignefs: whence he concludes, that the different Size of Animals isnbsp;entirely owing to the greater or lefs Numbernbsp;and Length of the Fibres J.

t Gortbr. Mtdic, Comftnd. p. 58, 59. LeeVW. 4tc. Hat. Tom. III. p. 58.nbsp;nbsp;nbsp;nbsp;1 Ibid. p. 61.

Thefc

Thefe flejhy Fibres appear, through their whole Length, encompafled with circularnbsp;Wrinkles. If a Thread were twilled aboutnbsp;a fine Needle in a Screw-like Form# withnbsp;fpiral Circumvolutions, fo that each Threadnbsp;be diftant from another the Diameter of thenbsp;Needle, it would naturally reprefent thenbsp;Manner of thefe circular Twiftings. Andnbsp;this Difpofition is wonderfully contrived fornbsp;the ready Dijlenfon or ContraSlion of thenbsp;Fibres: for as a Cord will be diftended ornbsp;contradled quicker or fower in Proportionnbsp;to its Length, the fame muft alfo be thenbsp;Cafe in Animal Fibres; and, therefore, onnbsp;thefe Principles we may calculate how muchnbsp;more nimbly the Leg of a Moufe can movenbsp;than the Leg of an Ox.

The Method of viewing the Mufcular Fibres is, to cut carefully, and with a very�nbsp;Iharp Razor or Penknife, a Slice of driednbsp;Flefli or Filh, as thin as poffible. Lay itnbsp;on a Piece of Glafs, and moillcn it withnbsp;warm Water; which drying foon away, willnbsp;leave the Veflels open and diftinguilhable.nbsp;�It is obfervable, that the Fibres of Filhnbsp;are larger than thofe of Fiefh.

That the Mufcular Fibres are vafcular, or made up of little hollow Veflels, is fuppofednbsp;by Malpighius, Borelli, Gorter, ournbsp;own Countryman Mr. Hooke, who fays,

they appeared to him like Strings of Pearls j and, very lately, by Dr. Alex. Stuart,nbsp;in his learned, and ingfenious Treatife deMo-tu Mufculorurn j where, from fuch a Structure, and by the Influx of the nervous Fluid,nbsp;he accounts, very reafonably, f�r the elafticnbsp;Force, the Contradtion, the Diftenfion, andnbsp;all the Adlions of the Mufcles ¹. But asnbsp;thefe Gentlemen difier fomewhat in the Figure of the little Veficles fuppofed to makenbsp;up the mufcular Fibres, the Curious will donbsp;well to examine, with the Microfcope, intonbsp;this Matter, as carefully as poflible; andnbsp;that by contriving all the Ways they cannbsp;think of to view the Fibres in living Animals. For, whatever Form the VeflTels maynbsp;have when replete with a nervous or othernbsp;Fluid, I am afraid, when the Fibres havenbsp;been dried, or the VeflTels collapfe togethernbsp;by not being fupplied with fuch Fluid, thenbsp;true Form and Structure of them can nevernbsp;be fully known.

Our Obfervations, it is probable, may be made with mofl; Succefs on InfeBs; theirnbsp;flefliy Fibres, as Mr. Leeuwenhoek tellsnbsp;us, being no lefs vifible than thofe of largernbsp;Creatures: which he found by cutting offnbsp;and examining the flefhy Parts of the Legsnbsp;of FlieSy GnatSy Ants -f-, amp;c. in all \yhich he

Vid- Gort�¹ de Fabrita Moiu Mufculer. Stuart de 'ttletu Mufe. p. 49, f Arc. Nat, Tom, III. p, 108.

could plainlydiftinguifh the circularWrinkles or Circumvolutions encompafling the Fibres,nbsp;as they are pidlured PlateXI. Fig. III.

UPON examining of Bones with a Afr-crofcope, their fuperficial Part is found to confift of a great many fmall Vedels, andnbsp;fome few of a larger Size; which laft, whennbsp;they come to the Surface of the Bone, appear invefted with either a Membrane ornbsp;bony Subftance perfectly tranfparent. Thenbsp;Inficfe of the Bone has a fpongyor cellularnbsp;Subftance, confifting of long Particles clofe-ly united, which are compofed of number-lefs fmall Veflels, fome�runnihg lengthways,nbsp;and others taking their Cdurl'e towards thenbsp;Sides of the bony Particles, which, not-withftanding their great Nufhber of Apertures, are extremely hard, and lie fome parallel, and others perpendicular, to the Lengthnbsp;of the Bone.

Mr. Leeuwenhoek difcovered, once, in a fmall Bit of a Shin-Bone, four or five Vef-fels, with Apertures large enough for a Silknbsp;to pafs through �, each whereof feemed fur-niflaed with a Valve, difpofed in fuch a Man-*

L 3 nbsp;nbsp;nbsp;ner

ner as to let out what was contained in the VelTel, but fufFer Nothing to return into it*.

** It may poflibly he conceived by fome, fays Dr. Grew, that the Bonesy at leaftnbsp;� fome of them, are hard at the firft : asnbsp;Salts and other cryftallizing Bodies are asnbsp;hard upon the very firfl Inftant of their*nbsp;** Shooting, as they are when grown intonbsp;� large Cryftals. But it is fo far evidentnbsp;� that all the Bones are foft at the firft, thatnbsp;I am of Opinion, they are originally anbsp;Congeries of as true Fibres or fibrous Vef-fiels as any other in the Body j which bynbsp;� Degrees harden into Bones, in like Man-ner as the inmoft Veflels of a Plant do innbsp;** Time harden into Wood. And as in anbsp;� Plant there are fucceflive Additions ofnbsp;Rings or Tubes of Wood, made out ofnbsp;** Veifels; fo in an Animal, it feems plainnbsp;** that there are Additions fucceflively madenbsp;** to the Bones out of the fibrous Barts of thenbsp;� Mufcles; efpecially thofe whiteft Fibresnbsp;** which run tranfverfely, and make the Sta-men or Warp of every Mufcle. So that,nbsp;** as in the Bark of a Plant, Part of the Vef-fels are fucceflively derived outward to thenbsp;** Rind, and Part inward to the Sap, whichnbsp;afterwards becomes hard Wood j fo, in thenbsp;Flefli of an Animal, Part of the whitenbsp;** tranfverfe Fibres are fucceflively derived

to the Skin (of which it chiefly cor^fifts), � and Part of them inwardly, making ftillnbsp;** new Periojieums one after another, as thenbsp;old ones become fo many Additions^ tPnbsp;** the Bones

Whoever would examine the BoneSy muft {have off, with a fharp Pen-knife, very thinnbsp;Pieces, lengthways, crofsways, and obliquely,nbsp;and that from the Infide, Outiide, and Middle of the Bone. Apply to the Microfcopenbsp;fome of thefe Shavings dry, and others moirnbsp;ftened with warm Water, and thus the Vef-fels will be feen in all Diredtions. But thenbsp;beft Way of (hewing the bony Structure is,nbsp;by putting the Bones in a very clear Firenbsp;till they are red-hot; then taking them outnbsp;carefully, you will find the bony Cells, tho�nbsp;tender, perfedt and entire : And being nownbsp;quite empty, they may be viewed with greatnbsp;Eafe and Pleafure.

CHAP. XIV.

Mr. Leeuwenhoek endeavoured to difcover, by his Microfcopey the Structnbsp;ture of the Nervesy in the Spinal Marrow

L 4 nbsp;nbsp;nbsp;of.

of an Oxj and faw, with great Delight, that minute hollow Veffels, of an unconceivablenbsp;Finenefs, inverted with their proper Membranes, and running out in Lengths parallelnbsp;to one another, make up their Comport tion.nbsp;And though fome hundreds of thefe VertTelsnbsp;go to the Formation of the leaft Nerve thatnbsp;can portlbly be examined, he did not onlynbsp;difcern the Cavities of them, which he computed to be three Times lefs than their Diameters, but, in fome, perceived the Orificesnbsp;as plainly as the Holes in a pricked Papernbsp;are to be feen when looked at againrt thenbsp;Sun. It requires, however, great Dexteritynbsp;and Expedition to make this Examinatiortnbsp;with Succefs j for after a thin Slice of thenbsp;Spinal Marrow is placed before the Micro-fcope, in lefs than a Minute�s Time it becomes dry, and the whole Appearance va-nifhes ¹.

The fame ingenious Enquirer into Nature examined likewife the Brain of fevetal Creatures, fuch as an Lidia)! Hen, a Sheeps annbsp;Ox, a Sparrow, See. and could there .dirtin-guifh Multitudes of Veffels, fo extremelynbsp;fmall, that if a Globule of the Blood (anbsp;Million whereof exceed not a Grain ofnbsp;Sand in Bignefs) were divided into five hundred Parts, thofe Parts would be too large

Of the Nerves. nbsp;nbsp;nbsp;147

to pafs into fuch Veffels. He obferved farther that the VelTels in the Brain of a Sparrow are not fmaller than in an Ox j andnbsp;argues from thence, that there really is nonbsp;other Difference between the Brain of a largenbsp;Animal and that of a fmall one, but only anbsp;greater or fmaller Number of VelTels; andnbsp;that the Globules of the Fluid palling thro�nbsp;them are in both of the fame Size.

Though it does not diredlly relate to Mi^ crofcopes, I hope I may be excufed for takingnbsp;Notice here, that in the Year 1711, Dodlornbsp;Alexander Stuart -f- made a Dilcovery,nbsp;that the Nerves are not elaftic, contrary tonbsp;the Opinion of all preceding Authors} andnbsp;proved it by the following Experiment:nbsp;� Laying a Piece of Twine, about fournbsp;� Inches in Length, parallel to the Nerve,nbsp;Artery,and Vein oftheinfide of the Thighnbsp;� in an human Subjedt, and tying thefe to-� gether, above and below, as foon as theynbsp;were cut out of the Body, and laid on anbsp;Board; the Artery and Vein were feen tonbsp;� contradl equally, to the Lofs of a quarternbsp;Part of the Length they had in the Bodynbsp;before Excifion ; but the Nerve continuednbsp;� of the fame Length with the Twine, asnbsp;in the Body.�

gt;7 nbsp;nbsp;nbsp;CHAP.

Jf^iivocal orfpontaneous Generation^ that is, a Produ�tion of Plants without Seeds,nbsp;and of living Creatures without any othernbsp;Parents but Accident and Putrefadlion, ho\y-cver abfurd it may feem to us, was an Opinion that prevailed almoft univerfally; tillnbsp;Microfcopes overturned it, by demonftratingnbsp;that all Plants have their Seeds, and all Animals their Eggs : whence other Plants andnbsp;other Animals, exactly of the fame Species,nbsp;are perpetually and unalterably produced.

Nothing feems now more contrary to Reafon, than that Chance and Najiinefsnbsp;fhould give a Being to Uniformity, Regularity, and Beauty ; that two fuch unlikelynbsp;Principles fhould produce, in different Places,nbsp;Millions of Vegetables of the fame Kinds,nbsp;and alike exadlly, even in the moft minutenbsp;Particularities: or, what is yet more amazing,nbsp;that dead corrupting Matter, and blind uncertain Chance, fhould create living Animals,nbsp;fabricate a Brain, conflitute Nerves iffuingnbsp;from it, compofe a Contrail; of Mufcles, fur-nifh out Eyes, Lungs, a Heart, a Stomach,nbsp;Bowels, and all other Parts ufeful to fuchnbsp;Creatures; and that too not after an aukward,

flovenly, variable, undefigning, and unfinished Manner j but with a Contrivance, Dexterity, Elegance, Perfeftion, and Con-flancy, beyond the utmoft Power of Art tonbsp;imitate. This, however, was the Opinion,nbsp;not only of the Ignorant and Illiterate, butnbsp;of the moft learned grave Philofophers of preceding Ages; and would probably ftill havenbsp;been taught and believed, had not Micro-fcopes difeovered the Manner how all thefenbsp;Things are generated, and reftored to Goo^nbsp;the Glory of his own amazing Works ¹,

The Eye, affified by a good Microfeopey can diftinguiih plainly, in the Semen Mafeu-linum of Animals, Myriads of Animalculesnbsp;alive and vigorous; though fo exceedinglynbsp;minute, that it is computed three thoufandnbsp;millions of them are not equal to a Grain ofnbsp;Sand, whofe Diameter is but the one hundredth Part of an Inch -I-. And the famenbsp;Inftrument will inform us, beyond all Doubt,nbsp;that the Farina of Vegetables are nothingnbsp;elfe but a Congeries of minute Granulaynbsp;whofe Shapes are conftant and uniform asnbsp;the Plants they are taken from. And as the

I would as foon fay, that Rocks and Woods engender Stags and EiephaAts, as affirm, that a Piece of Cheefe generates Mites. Stags are born and live in Woods, and Mites innbsp;Cheefe ; but they both owe their Being to that of other Ani-Sials. SpeSi. dt la Nat. Eng. Edit. lamo, Vol. II. p. 11.nbsp;t Vid, Keil�s Anat. 5th Edit. p. ti6.

Seeds of Plants are proved, by repeated Experiments, to be unprolific, if the Farintz be not permitted to fhed, it has been fup-pofed, that all its Granula contain feminalnbsp;Plants of their own Kind.

The Growth of Animals and Vegetables feems to be nothing elfe but a gradual Unfolding and Expanfion of their Vedels, by. anbsp;flow and progreflive Infinuation of -Fluidsnbsp;adapted to their Diameters ; until, beingnbsp;ilretched to the utmoft Bounds appointednbsp;them by Providence at their Formation, theynbsp;attain their State of Perfe�lion, or, in othernbsp;Words, arrive at their full Growth.

It is thought probable, according to this Theory, that in Animals (of the larger andnbsp;more perfect Kind at leaft) the kernen of thenbsp;Male being received into the Matrix of thenbsp;F'emale, fome of the Animalcules it containsnbsp;in fuch Abundance find an Entrance intonbsp;the Ovaria, and lodge themfelves in fomenbsp;of the Ova placed there by Providence as anbsp;pr*opcr Nidus for them.

An Ovum becoming thus inhabited by an Animalcule, gets loofened in due Time fromnbsp;its Ovarium, and paffes into the Matrixnbsp;through one of the Fallopian Tubes. Thenbsp;Veins and Arteries that faftened it to thenbsp;Ovary, and were broken when it droppednbsp;from thence, unite with the Veffels it findsnbsp;here, and compofe the Placenta. The Goatsnbsp;of the Ovum, being fwelled and dilated by

the Juices of the Matrix, form the other Integuments needful to the Prefervation ofnbsp;the little Animal; which receiving continually a kindly Nourifhment from the famenbsp;Juices, gradually ftretches and enlarges itsnbsp;Dimenfions, becoming then quickly vifiblenbsp;with all the Parts peculiar to its Species,nbsp;and is called a Fcetus.

In Plants, which are uncapable of removing from Place to Place as Animals can, it was requifite a Repolitory for their Fari^nbsp;nee Ihould be near at hand, to prevent itsnbsp;being loft: and accordingly we find, thatnbsp;every Flower producing a Farina has like-wife in itfelf a proper Uterus for the Reception of it: where the Ova thereby impregnated are expanded by the Juices of thenbsp;Parent Plant to a certain Form and Bulk;nbsp;and then becoming what we call ripe Seeds,nbsp;tliey fall to the Earth, which is the naturalnbsp;Matrix for them.

According to the above Suppofition, a ripe Seed falling to the Earth is in the Conditionnbsp;of the Ovum of an .Animal getting loofenbsp;from its Qvary, and falling into the Uterus :nbsp;and, to go on with the Analogy, the Juicesnbsp;of the Earth fwell and expand the Veflelsnbsp;of the Seed, as the Juices of the Uterus donbsp;thofe of the Ovum, till the feminal Leavesnbsp;unfold, and perform the Office of a Placentanbsp;to the Infant-included Plant; which imbibing fuitable and fufficient Moifture, gradually

dually extends its Parts, fixes its own Root, Ihoots above the Ground, and may be faidnbsp;to be born.

As Difcoveries made by the Microfcope, of infinite Numbers of Animalcules in the Setnennbsp;Mafculinum of all living Creatures, and like-wife of a Regularity and Conftancy in thenbsp;Farina of each Species of Vegetables, analogous to the faid Animalcules in the Animalnbsp;Semen, have been the principal Means ofnbsp;convincing us that all Things are producednbsp;by Parents of their own Kind, according tonbsp;the eternal and unalterable Laws eftablifhednbsp;at their firft Creation j I hope this fhortnbsp;Account of Generation, before my enteringnbsp;upon thofe Subjedls, will not be judged improper.

At the Beginning of the Year 1678, Mr. Nicholas Hartsoeker ofnbsp;Rotterdam declared, in a Treatife of Diop~nbsp;tries by him then publilhed, that it wasnbsp;twenty Years fince he firft began to examinenbsp;the Semen Mafculinum of feveral living Creatures by the Help of Microfcopcs: that, as

far as he knew, he was the firft Perfon who had ever done fo j that he had found in fuchnbsp;Semen infinite Numbers of Animalcules, moftnbsp;exceedingly minute, almoft in the Shape ofnbsp;Tadpoles or young Frogs; and that he hadnbsp;made this Difcovery known to the Worldnbsp;in the 30 th of the Ephemerides Eruditorum,nbsp;printed at Paris in the fame Year 1678.

Mr. Leeuwenhoek:, in the 113th of his Epiftles (dated �January 1678) is verynbsp;angry at this Claim; and aflerts, that henbsp;himfelf firft difcovered the Animalcules innbsp;Semine j and fent Account thereof to thenbsp;Royal Society in November itjj, as henbsp;proves by the Fhilofophical EranfaSlions, pub-liflied in Decembernbsp;nbsp;nbsp;nbsp;and in January

and February 1678. Nay, he farther affirms, that Letters had pafled between him andnbsp;Mr. Oldenburg on this Subje�t in 1674.nbsp;This Difpute concerns us no farther than asnbsp;it fliews about what Time the Exiftence ofnbsp;thefe Animalcules was firft difcovered, whichnbsp;fome of my curious Readers may perhaps benbsp;inquifitive to know.

The general Appearance or Figure of the Animalcules in the Semen Mafculinum of dif*.nbsp;ferent Kinds of living Creatures is very muchnbsp;the fame: that is, the Bodies of them allnbsp;feem of an oblong oval Form, with long tapering flender Tails iffuing therefrom ; andnbsp;as by this Shape they foipev/hat refemble

'Tadpoles, they have frequently been called by that Name; though the Tails of them, innbsp;Proportion to their Bodies, are much longernbsp;than the Tails of Tadpoles are: and it is ob-fervable, that the Animalcules in the Semennbsp;of Fiflaes have Tails much longer and flen-derer than the Tails of thofe in other Animals, infomuch that the Extremity of themnbsp;is not to be difcerned without the bed; GlalTesnbsp;and the utmoft Attention : their Bodies arenbsp;alfo much fmaller.

In the Spring-Seafon, at the Time that Frogs engender, upon opening the Tefticlesnbsp;of a Male, and applying fomc of th^feminalnbsp;Matter before the Microfqope, Multitudesnbsp;of Animalcules appeared therein, about ¹ onenbsp;thoufandth Part of the Thicknefs of the Hairnbsp;of a Man�s Head, as nearly as could be computed : whence it follows, that a thoufandnbsp;Millions of them would be -but equal to anbsp;Globe whofe Diameter is the Thicknefs ofnbsp;the Hair of a Man�s Head. And there feem-ed to be ten thoufand of them at lead fornbsp;each one of-the female Ova,

♦ -.i - nbsp;nbsp;nbsp;gt;■•..•nbsp;nbsp;nbsp;nbsp;^nbsp;nbsp;nbsp;nbsp;' -*■nbsp;nbsp;nbsp;nbsp;•

Upon viewing the Milt or Semen Mafcu-linum of a living Cod-fith with a Microjcope, fuch Numbers of Animalcules with longnbsp;Tails were found therein, that at leaft tennbsp;thoufand of them were fuppofed to exift innbsp;the Quantity of a Grain of Sand. Whencenbsp;Mr. L,eeUWEN HOEK argues, that the Miltnbsp;of that (ingle God-fi(h contained more livingnbsp;Ajiimalcules than there are People alive uponnbsp;the Face of the whole Earth at one and thenbsp;fame Time : for he computes *, that onenbsp;hundred Grains of Sand make the Diameternbsp;of an Inch j wherefore in a cubic Inch therenbsp;will be a million of fuch Sands. And as henbsp;found the Milt of the Cod-(i(li to be aboutnbsp;fifteen cubic Inches, it mud: contain fifteennbsp;millions of Quantities as big as a Grain ofnbsp;Sand. Now if each of thefe Quantities contain ten thoufand Animalcules, there mud:nbsp;be in theWhole one hundred and fifty thoufand millions.

Then, to find out, in a probable Manner, theNumber of People living upon the wholenbsp;Earth at one Time; he reckons, that in anbsp;great Circle there are five thoufand four hundred Dutch iopxzxe:. Miles ; whence he calculates the Surface of the Earth to containnbsp;nine millions two hundred feventy-fix thou-

fand two hundred and eighteen fuch fquare Miles : and fuppofing one Third of thenbsp;Whole, or three millions ninety-two thou-fand and feventy-two Miles, to be dry Land;nbsp;and of this, two thirds, or two millionsnbsp;lixty - one thoufand three hundred andnbsp;eighty-two Miles, to be inhabited: and fuppofing farther, that Holland and Wef-Fricf-land are twenty-two Miles long and fevennbsp;broad, which make one hundred and fifty-four fquare Miles; the habitable Part of thenbsp;World is thirteeen thoufand three hundrednbsp;and eighty-five Times the Bignefs o�Hollandnbsp;and Wefi-Friefand.

Novy, if the People in thefe two Provinces be fuppofed a million, and if all the othernbsp;inhabited Parts of the World were as populous as the.fe (which is highly improbable), there would be thirteen thoufand threenbsp;hundred and eighty-five millions of Peoplenbsp;on the Face of the whole Earth : but thenbsp;Milt of this Cod-fifh contained one hundrednbsp;and fifty thoufand millions of Animalcules,nbsp;which is ten Times more than the Numbernbsp;of all Mankind.

The Number of thefe Animalcules may be computed another Way : for the ingeniousnbsp;Author of SpeSlacle de la Nature fays that

three curious People counted, with all the Care they were able, as many of the ^ggsnbsp;or Row of a female Cod-fifla as weighed anbsp;Dram, and agreed pretty well in the Number, which they wrote down. They thennbsp;Weighed the whole Mafs; and fetting downnbsp;eight Times the Sum of one Dram for everynbsp;Ounce, which contains eight Drams, allnbsp;the Sums together produced a Total of ninenbsp;millions threehundred and thirty-four thou-fand Eggs ¹.

Now fuppofing (as Mr. Leeuwenhoek does of the Semen Mafculinum of Frogs) thatnbsp;there are ten thoufind Animalcules in thenbsp;Milt for each one of the Female Ova in thenbsp;Row, it will follow, that fince the Femalenbsp;Row is found to have nine Millions threenbsp;hundred thirty-four thoufand Eggs, thenbsp;whole Milt of the Male may be reckoned tonbsp;contain ninety-three thoufand four hundrednbsp;and forty millions of Animacules: which,nbsp;though greatly fhort of the firft Calculation,nbsp;is almoft feven Times as many as the wholenbsp;human Species.

Four Millions and ninety-fix thoufand Eggs were com¹ Puted in the Roe of a Crab, each of which received itsNou-��ifhment by a Rope from the Crab's Body, Vide Arc. Nat,nbsp;Tom. I. Par. 11. p. 24\0gt;

Hair of his Head near them, which Half through his Microfcope appeared an Inch innbsp;Breadth; and he was fatisfied that at lead;nbsp;fixty fuch Animalcules could eafily lie withinnbsp;that Diameter; whence, their Bodies beingnbsp;fpherical, it muft follow, that two hundrednbsp;and lixteen thoufand of them are but equalnbsp;to a Globe whofe Diameter is no more thannbsp;the Breadth of fuch an Hair.

He obferved, that when the Water wherewith he had diluted the Semen of anbsp;Cod-fifla was exhaled, the little Bodies ofnbsp;the Animalcules burft in Pieces, which didnbsp;not happen to thofe in the Semen of a Ram;nbsp;which he imputes to the greater Firmnefsnbsp;and Confillency of the latter, as the Flefh ofnbsp;a Land-Animal is more compa�l than thatnbsp;of a Fifla. He likewife takes Notice, thatnbsp;the Tails of thofe in Fifhes are fo extremelynbsp;fender,- that he could never be certain ofnbsp;his feeing the very Tips or Extremities ofnbsp;them.

In the Milt of a Jack at leaf ten thoufand Animalcules were diicernible in anbsp;Quantity not bigger than a Grain of Sand,nbsp;exactly in Appearance like thofe of the Cod-fifh ; and upon putting J four Times asnbsp;much Water to it, they were perceived tonbsp;become fronger and brifker, and to fwim

as if in Purfuit of Prey, with greater Velocity ; though (being viewed in a capillary Tube) their whole Courfe was no longernbsp;than the Diameter of a Hair.

If you would view the Animakules in the Milt or foft Row of Fifhes, fqueeze out anbsp;little of it, and putting the C^antity of anbsp;Pin�s Head upon a lingle Ifinglafs, dilute itnbsp;with Rain orRiver Water, till the little Creatures have fufficient Room to fwim aboutnbsp;freely, and flaew themfelves to Advantage;nbsp;which they can by no means do unlefs itnbsp;be made very thin. Or, after you havenbsp;mixed fome Water with it, apply it to thenbsp;Mtcrofcope in one of your fmallell capillarynbsp;Tubes j which Way Mr. Leeuwenhoeknbsp;informs us he found the moft ufeful for thenbsp;Examination of the Semen of different Creatures. [N. B. * The Eggs in the Row, andnbsp;Anmalcules in the Milt, of Fiflaes of onenbsp;Year old, are as large as in thofe of the famenbsp;Species of twenty Years old.]

Upon opening the Seminal Veffels of a Cock, fqueezing out a fmall Drop of the Semen, and viewing it with a Microfcope, Legions of Animalcules appeared therein, fwim-J�iing in Crowds together, and crofling one

another with as much Brilknefs and Vigour as if the Cock had been but newly dead, tho�nbsp;it was killed the Day before : and by feve-ral Trials on the Semen of other Cocks, itnbsp;has been found, that the Animalcules thereinnbsp;will live many Hours in a capillary Glafsnbsp;Tube. To a flight Obferver they feem innbsp;the Form of Eels j but if the greatefl: Magnifiers be ufed with due Attention, they willnbsp;be foud fhaped as Fig. III. Plate XII.�nbsp;Their Size is fo extremely minute, that anbsp;* million of them are fuppofed not to exceed the Bignefs of a Grain of Sand; andnbsp;their Tails cannot be difcerned without muchnbsp;Difficulty, being ten thoufand Times morenbsp;flender than the Hair of a Man�s Hand.

A little of the Seminal Matter taken from the Tefticle of a Dog abounded with Animalcules -f, a million whereof would hardlynbsp;equal a large Grain of Sand : and after fomenbsp;of this Matter had been kept Seven Days innbsp;a Glafs Tube, feveral of foe: Animalcules remained alive and vigorous. [Their Form isnbsp;fliewn Fig. IV.]�The Tfefiicles of a Hare,nbsp;though four Days dead, were alfo exceedingly full of Animalcules like thofe in Dogs,nbsp;fwimming in a clear Liquor, but withoutnbsp;Motion.

Killing a Female Rabbet immediately after the Coitus, and opening the Uterus thereof, innumerable Animalcules were found in a fmall Drop, taken from the Mouth of thenbsp;Fallopian Tube, where it opens into the Matrix : but none were difcerned in the Uterusnbsp;itfelf, or farther along the Tube. They hadnbsp;long Tails, and for the moft Part ¹ fixnbsp;tranfparent Globules appeared on the Bodynbsp;of each, as in Fig. V. i. though fome hadnbsp;only one Globule at the End of the Body,nbsp;and another in the Tail, as Fig. V. 2.

Examining a 'Drop of Semen taken from the Tefticles of a Ram, it abounded withnbsp;Animalcules in as great Numbers as the fe-minal Matter of other Creatures j but withnbsp;this extraordinary Singularity, that Multitudes of them fwam the fame Way together.

,t Mr. Leeuwenhoek opened the Uterus of an Ewe, which about fcventeen Days before had been coupled withnbsp;a Ram, and in one of the Cornea obferved a little reddipnbsp;fiepy Subfiance, wherein no Shape could be diftinguilhed. Henbsp;put this in a Glafs Tube the Thiclcnefs of a Quill, filled withnbsp;Oil of Turpentine, and applied it to his Micro/cope ; but couldnbsp;make nothing of it in that Manner. Wherefore he took itnbsp;from the Tube, and extending it very gently out of the roundnbsp;Figure in which it lay, he perceived extremely plain thenbsp;Formation of all the Vertebr�, with the Blood-Veflels andnbsp;Ramifications palling over them, and in two Places could feenbsp;the Spinal Marrow, He could alfo diftinguilh not only thenbsp;Head, but alfo the Mouth, Brain, and Eyes, the Bignefs ofnbsp;two Grains of Sand, and clear as Cryftal; He faw likewife

gether, and feemed to have the Inclination of Sheep, to follow their Leader and movenbsp;in Flocks. Mr. Leeuwenhoek fays, henbsp;found fo much Pleafure in obferving this,nbsp;that he called in fome Neighbours to fharenbsp;it with him.

A Buck being killed in Rutting-time, the �* Vafa Deferentia were found turgid with a,nbsp;milky Fluid, a Drop whereof, when appliednbsp;to the Microfcope, appeared full of Animal^nbsp;cules moving very brifidy. The greateftnbsp;Difficulty was to lay them properly beforenbsp;the Microfcope: for when the Matter is toonbsp;thick, nothing can be feen but a confufednbsp;Motion, and when fpread thin it dries awaynbsp;immediately j but by diluting it with warmnbsp;Water, juft enough to change its Colour,nbsp;they were feen diftindlly.

The h.nrmn'Seinen has likewife been viewed by the Microfcope, and found no lefs the Ribs and Tntedines ; though the whole Creature was nonbsp;larger than the eighth Part of a Pea.�After this, he openednbsp;the Uterus of another Ewe, but three Days from the Coitus ;nbsp;and fearching the Liquor coming from it very diligently withnbsp;a Magnifying Glafs, obferved a little Particle the Size of anbsp;Grain of Sand ; which examining with an excellent Micro-jcope, he with great Pleafure found to be an exceeding minutenbsp;Lamb lung round in its Integuments, and could plainly dif-cern its Mouth and Eyes. Vid. Arc. Nat. Tom. I. Par. ILnbsp;pag. 165, and ly v

plentifully flocked with Life than that of other Animals: for more than ten thoufandnbsp;living Creatures were feen, by Mr. Leeuwenhoek, moving in no larger a Quantitynbsp;of the fluid Part thereof than the Bignefs ofnbsp;a Grain of Sand; and in the thicker Partnbsp;they were fo thronged together, that theynbsp;could not move for one another. Their Sizenbsp;was fmaller than the red Globules of thenbsp;Blood, and even lefs thin the millionth Partnbsp;of a Grain of Sand The Bodies of themnbsp;are roundifti, femewhat flat before, but ending fharp behind, with Tails exceedinglynbsp;tranfparent, five or fix Times longer, andnbsp;about fiveTimes more flender, than theirBo-dies. They move themfelves along by thenbsp;violent Agitation of their Tails, in variousnbsp;Bendings, after the Alanner that Eels or Serpents fwim : and fometimes their Tails arenbsp;moved thus eight or ten Times in gettingnbsp;forwards the Diameter of a Hair.

It is wonderful to confider the Minutenefs of thefe little Animals, and particularly thenbsp;amazing Slendernefs of their Tails : whichnbsp;mufl, notwithflanding, be furnifhed with asnbsp;many Joints as the Tails of larger Creatures,nbsp;fince they are able to move them with great

Agility: and, befides, every one of thefe Joints muft be provided with its proper Muf-cles, Nerves, Arteries, and Veins j and alfonbsp;with Fluids circulating thro� them, and fup-plying them with Nourifhment, Strength,nbsp;and Motion. In fliort, the Mind lofes itfelfnbsp;in contemplating a Minutenefs beyond allnbsp;human Conception; tho� Reafon tells us itnbsp;certainly muft be. I remember Dr. Powernbsp;has a fine Paflage to this Purpofe in thenbsp;Preface to his Experiments: It has oftennbsp;� feemed to me (fays he) an ordinary Pro-�� bability, and fomething more than Fancynbsp;� (how paradoxical foever the Conjefturenbsp;�� may feem), to think, that the lead; Bodiesnbsp;we are able to fee with our naked Eyesnbsp;are but middle Proportionals, as it were,nbsp;betwixt the greateji and the fmallef Bo-dies in Nature ^ which two Extremesnbsp;� lie equally beyond the Reach of humannbsp;� Senfation. � For, as on one Side they arenbsp;� but narrow Souls, and not worthy thenbsp;Name of Philojophers, that think anynbsp;� Body can be too great or too vaji in itsnbsp;� Dimenfions : fo likewifc are they as in-apprehenfive, and of the fame Litter withnbsp;� the former, that, on the other Side, thinknbsp;� the Particles of Matter may be too little,nbsp;** or that Nature is ftinted at an Atom, andnbsp;� mud; have a Non ultra of her Subdivi--��* fions.�

As the Animalcules in the Semen Mafculi-num of different Creatures are not much unlike in Shape, it is alfo obfervable, that they do not differ in ¹ Bignefs according to thenbsp;Sizes of the Creatures they are taken from jnbsp;but feem, in this refpeft, analogous to thenbsp;Seeds of Trees and Plants, whofe Size bearsnbsp;very little Proportion to the Bignefs of thenbsp;Trees and Plants producing them. Thenbsp;Seed of an Apple, for Inftance, is fomenbsp;thoufands of Times fmaller than a Cocoa-Nut, tho� the Trees they grow on have notnbsp;that Difproportion : and the S�eds of Tobacco (whereof a thoufand weigh notnbsp;above a fingle Grain) are lefs beyond Com-parifon than many Kinds of other Seeds whofe'quot;nbsp;Plants are not near fo large as Tobacco is.nbsp;Hence it comes to pafs, that Animalculesnbsp;may be difeovered in the Semen of the final lefl;nbsp;Birds,Quadrupeds, and Fifhes, nay, and evennbsp;in Infedts too. For Mr. Leeuwenhoeknbsp;affures us, he found a white Matter he hadnbsp;fometimes fqueezed from the hinder Parts ofnbsp;male J Spiders, about the Bignefs of a Grainnbsp;of Sand, to be indeed their Semen, by difeo-vering therein prodigious Multitudes ofAni^nbsp;malcules, which continued living above fivenbsp;Hours, but were fo extremely minute thatnbsp;he fuppofes a thoufand Millions of them

Arc. Nat. Tom. IV. pag. 30. t Dr- Power�s Ex-periro. pag. 30. nbsp;nbsp;nbsp;| Philo/oph.Tran/a�. Numb. 279.

would not equal the Size of a Grain ofMillet. He found them likewife in the Semen of thenbsp;Dormoufe % in Oyfters �, in Silkworms % innbsp;the Labella minimart or fmall Dragon-Fly,nbsp;in the Common Fly % in the male Flea \ innbsp;Gnats and in feveral other Infedls : and,nbsp;without doubt, a curious Enquirer will benbsp;able todifeover them in Abundance of Subjects yet unexamined j for Nature is uniform in all her Works, and there is goodnbsp;Reafon to believe that they certainly exift innbsp;all the animal Part of the Creation.

Amongft the many Species of Animalcules obferved in Waters and Infulions, there arenbsp;none found refembling thofe in Semine � ;nbsp;but the Animalcules in the Semen of all Sortsnbsp;of Creatures hitherto examined have a common and general Likenefs to one another jnbsp;with this Particularity, that they appear innbsp;continual Motion, without the leaf! Reft ornbsp;Intermiftion, provided the Fluid be fufficientnbsp;for them to fwim about in.

Many People have imagined, that living Creatures might alfo be found in the othernbsp;animal Juices: but, after the ftriCleft andnbsp;moft careful Examination, it appears certain

* Jrc. Nat. Tom. I. Par. II. p. 2j. Ibid. Tom. 11. P^r. I. p. 144.nbsp;nbsp;nbsp;nbsp;Ibid. Par. II. p. 422. Ibid. Tom. IV.

that nothing with the leaft Token of Life is to be difcovered by the beft Glafles, eithernbsp;in the Blood, Spittle, Urine, Gall, Chyce,nbsp;or any of the Humours, except the Semennbsp;only.

THough no Animalcules can be found in the Saliva or Spittle, great Numbersnbsp;of different Kinds may be difcovered in thenbsp;Hvhitijh Matter fticking between the Teeth,nbsp;if it be picked out with a Pin or Needle,nbsp;mixt with a little Rain-V/ater and Spittlenbsp;without Bubbles, and applied before the Mi-crofcope. And fometimes they are fo incredibly numerous, and fo full of Motion, thatnbsp;the whole Mafs appears ^live.

* The largeft Sort (ftiewn Plate XIII. Fig. I. Numb. 1.) move along very fwiftlynbsp;in the Spittle or Water ; of thefe there arenbsp;but few.

The fecond Sort are more numerous, and have a Motion peculiar to themfelves, as re-prefented Numb. 2.

The third Sort are roundldi, and fo minute, that a Grain of coarfe Sand would equal a million of them in Bignefs : theynbsp;move fo fwiftly, and in fuchMultitudes, thatnbsp;they feem like Swarms of Gnats or Flies,nbsp;and the exadl Shape of them is not ealy tonbsp;be diftinguifhed.

Some or all of thefe three Kinds may be found pretty conftantly in the Matter takennbsp;from between the Teeth of Men, Women,nbsp;or Children; efpecially from between thenbsp;Grinders, even tho� they walli their Teethnbsp;continually, and clean them with the utmoftnbsp;Care : but from the Teeth of People that arenbsp;more carelefs, the faid Matter affords anothernbsp;Sort of Animalcules in the Shape of Eels ornbsp;Worms, as piftured Numb. 4. Thefe movenbsp;themfelves. backwards, or forwards, withnbsp;great Bendings of the Body; and force theirnbsp;Way through the minuter Animalcules everynbsp;where around them, with the fame Eafe asnbsp;a, large Butterfly would break through anbsp;Swarm of Gnats. There are likewife, innbsp;this Matter from the Teeth, other Sorts ofnbsp;Animalcules, whofe Motions are fo extremelynbsp;languid, that without long Attention theynbsp;cannot be diftinguiflied to be alive.

Obfervation. They all die if Vinegar be applied to them �, whence it feems reafonablenbsp;to conclude, that walking the Teeth andnbsp;Gums with Vinegar may be a Means of pre-ferving them from thefe minute Creatures.

TH E Microfcope has difcovered, what without it could fcarce have been imagined, that the Diftemper we call the Itchnbsp;is owing to little Infedls under the Cuticula,nbsp;whofe continual Bitings caufe an ouzing ofnbsp;Serum from the Cutis, and produce thofenbsp;Puftules or watry Bladders whereby this Dif-eafe is known. This was found out bynbsp;Dr. BonoNio, * who obferving that itchynbsp;People frequently pull out of their fcabbynbsp;Skin little Bladders of Water with the Pointnbsp;of a Pin, and crack them on their Nails likenbsp;Fleas, he determined to examine what thefenbsp;Bladders might really be. Wherefore, picking out with a fine Needle a little Puftulenbsp;from a Place fcabbed over, and where therenbsp;was a fevere Itching, he fqueezed a thinnbsp;Matter from it, and perceived a very final!nbsp;white Globule fcarcely difcernible, which,nbsp;applying to the Microfcope, he found to benbsp;a very minute Animal, in Shape refembling anbsp;Tortoife, of a whitilli Colour, but darker onnbsp;the Back than elfewhere, with fome longnbsp;and thick Hairs ifluing from it, very nimblenbsp;in its Motion, having fix Legs, a fliarp Head,

and two little Horns ; being in Shape as re-prefented by the two Pi�lures, Fig. II. a, b. Plate XIII. ^

This Experiment was repeated on itchy Perfons of all Ages, Sexes, and Complexions,nbsp;and at all Seafons of the Year, and he con-*ftantly found the fame Animalcules in mod:nbsp;of the watry Puftules : and though by rca-fon of their Minutenefs and Colour (whichnbsp;is the fame as the Skin) it is difficult to dif-cern thefe Creatures on the Surface of thenbsp;Body, yet he fometimes faw them upon thenbsp;Joint of the Fingers in the little Furrov/s ofnbsp;the Cuticula, where they firft begin to enternbsp;with ther (harp Heads, gnawing and working in their Bodies, till they are got quitenbsp;under the Cuticula, where they burrow fromnbsp;Place to Place, caufe a troublefome and grievous Itching, and force the infedted Perfonnbsp;to fcratch, which only ferves to increafe thenbsp;Malady; for, by breaking the little Puftulesnbsp;and fome fmall Blood-Veffiels, Scabs, cruftynbsp;Sores, and fuch like foul Symptoms enfue:nbsp;whilft thefe mifchievous Ainmalcules efcapenbsp;the Nails by their Minutenefs, and difperfenbsp;themfelves th� Farther.

Frequently obferving thefe Animalcules, he perceived one of them drop a little oblongnbsp;white Egg, almoft tranfparent, from thenbsp;hinder Part of its Body : and afterwards henbsp;faw many of the fame Sort of Eggs ; whichnbsp;proves them generated, like other Creatures,

from

from a Male and Female, though he was never able to diitinguilh the Sex of any henbsp;examined.

We may hence account how this Diftem-per comes to be fo very catching, hnce thefe Animalculesi by fimple Contact, can eafiiynbsp;pafs from one Perfon to another, having notnbsp;only a fwift Motion, but clinging to everynbsp;Thing they touch, and crawling as well uponnbsp;the Surface of the Body as under the outward Skin; and a few being once lodged,nbsp;they multiply apace by the Eggs they lay.nbsp;The Infe�tion may alfo be propagated in anbsp;like Manner by Sheets, Towels, Handkerchiefs, or Gloves, ufed by itchy People;nbsp;lince thefe Ajtimalcuks may eafily be harboured in fuch Things, and will live out ofnbsp;the Body two or three Days.

The Difcovery of thefe Animalcules thews the Reafon likewife why this Diftemper isnbsp;never to be cured by internal Medicines :nbsp;but requires lixivial Wafhes, Baths, or Ointments, made up with Salts, Sulphurs, Vitriols, Mercury, Precipitate, Sublimate, ornbsp;fuch Kinds of penetrating and corroding Remedies as can powerfully kill thefe Verminnbsp;in the Skin. And if fometimes we find thenbsp;Difeafe returns upon us, in a little while after we fuppofed it quite cured by Undtion, itnbsp;is no great Wonder; fince, tho� the Oint-

inent may deftroy all the living Ammlcuks^ it may not probably kill their Young Onesnbsp;in the Eggs, laid in Neds in the Skin;nbsp;which, coming to hatch, may renew thenbsp;Diftemper. For this Reafon it is advifeablenbsp;to continue the Anointing for fome Days,nbsp;even after the Cure feems perfedt.

TH E Cuticula, Scarf-Jkin, or outward Covering of the Body, is remarkablenbsp;for its Stales and for its Pores.

Its Scales are a Difcovery of the Micro-fcope; for being fo minute that ¹ two hundred of them may be covered with a Grain of Sand, they could never be difcerned bynbsp;the naked Eye. They are placed as onnbsp;Fhlaes, -f- three deep, that is, each Scale is fonbsp;far covered by two others, that only a thirdnbsp;Part thereof appears ; which lying over onenbsp;another, may be the Caufe why the Skin ofnbsp;the Body appears :|; white; for about thenbsp;Mouth and Lips, where they only juft meetnbsp;together, and do not fold over, the Blood-

Vid. Arc. Nat. Tom. I. Par. II. p. 208. Again� Tom. IV. p. 46. Ibid. p. 47. J Ibid. P' 5¹-

Veffels are feen through, and the Parts look red. The perfpirable Matter k fappofed tonbsp;iflue between' thefe Scales (which lie overnbsp;the Pores or excretory Veffels through whichnbsp;the watery and oily Humours perfpire), andnbsp;may find Vent in an hundred Places roundnbsp;the Edges of each Scale ; fo that, if a Grainnbsp;of Sand can cover two hundred Scales, itnbsp;will be able to cover twenty thoufand Placesnbsp;where Perfpiration may iffue forth.

A Piece of Skin taken from between the Fingers, from the Forehead, Neck, Arms,nbsp;or any other foft Part of the Body whichnbsp;is not hairy, ferves beft to ftiew the Scales ;nbsp;for where the Skin is callous, they are glew-ed as it were together.

If they are fcraped off wdth a Penknife, put into a Drop of Water, and fo applied tonbsp;the Microfcope, they will be feen to goodnbsp;Advantajje.

[ 174 ]

Every Part of the human Skin is full of excretory DuBs or Pores, which emitnbsp;fuperfluous Humours continually from thenbsp;Mafs of the circulating Fluid.

In order to view the Pores, cut a Slice of the upper Skin with a {harp Razor as thinnbsp;as poffible : then immediately cut a fecondnbsp;Slice from the fame Place, which apply tonbsp;the Microfcope, and in a Piece not largernbsp;than a Grain of Sand can cover, innumerable Pores will be perceived, as plainly as littlenbsp;Holes pricked by a fine Needle may be dif-cerned if it be held up againft the Sun. Thenbsp;Scales of the outer Skin prevent any diflind:nbsp;View of the Pores, unlefs they are fcrapednbsp;away with a Penknife, or cut off in the abovenbsp;Manner j but if a Piece of the Skin betweennbsp;the Fingers, or in the Palms of the Hands,nbsp;be fo prepared, and then examined, thenbsp;Light will be feen very pleafantly throughnbsp;the Pores.

ber of Tores in a human Body. He ¹ fup-pofes there are one hundred and twenty fuch Pores in a Line one tenth of an Inch long ;nbsp;however, to keep within Compafs, he reckons'nbsp;only one hundred. An Inch in Length willnbsp;then contain a thoufand in a Row, and anbsp;Foot twelve thoufand. According to thisnbsp;Computation, a Foot fquare muft have innbsp;it an hundred and forty-four millions : andnbsp;fuppofing the Superficies of a middle-fizednbsp;Man to be fourteen Feet fquare, there willnbsp;be in his Skin two thoufand and fixteen millions of Pores.

To acquire fome clearer Idea Hill of this prodigious Number of Pores by our Conception of Time, let us reckon with -f¹nbsp;Mersennus, that each Hour confifis ofnbsp;lixty Minutes, and each Minute of fixtynbsp;Seconds, or fixty Pulfations of an Artery 5nbsp;in one Hour there will then be three thoufand and fix hundred Pulfes j in twenty-fournbsp;Hours eighty-fix thoufand and four hundred ; and in a Year thirty-one millions fivenbsp;hundred and thirty-fix thoufand. But there,nbsp;are about fixty-four Times as many Poresnbsp;in the Surface of a Man�s Skin, and therefore he mull live fixty-four Years, ere henbsp;will have a Pulfation for every Pore in hisnbsp;Skin.

Dr. Nathanael Grew obferves, that the * Pores through which we perfpire arenbsp;more particularly remarkable in the Handsnbsp;and Feet; for if the Fland be well wafhednbsp;with Soap, and examined with but an indifferent Glafs, in the Palm, or upon the Endsnbsp;and firil Joints of the Thumb and Fingers,nbsp;innumerable little Ridges parallel to eachnbsp;other, of equal Bignefs and Diftance, will benbsp;found; upon which Ridges the Pores maynbsp;be perceived by a very good Eye, lying innbsp;Rows, even without a Glafs : but, viewednbsp;through a good Glafs, every Pore feems likenbsp;a little Fountain, wdth the Sweat ftandingnbsp;therein as clear as Rock-Water ; and, ifnbsp;wiped away, it will be found immediatelynbsp;to fpring up again.

When we confider the Multitude of Ori-fces all over the Skin, it is reafonable to imagine, that minute Animals, as Fleas,nbsp;Lice, Gnats, amp;c. do not with their llendernbsp;Inftruments make new Perforations, butnbsp;rather thruft or infinuate them into the Vef-fels cf the Skin, and fuck out the Blood, ornbsp;w^hat other Humour is their proper Aliment.

f 177 ]

I or Skin, that we are able to difcover more of what paffes within its Body thannbsp;in moil other living Creatures; which renders it a delightful Objeft for the Micro-fcope.

It has naturally three * Divifions, namely, the Head, the Breafl, and the Belly or Tail-part.�In the Head appear two fine blacknbsp;Eyes, with a Horn that has five Joints, andnbsp;is furrounded with Hairs, ftanding beforenbsp;each Eye; from the End of the Nofe ornbsp;Snout there is a pointed projedtingPart, ferv-ing for a Sheath or Cafe to a Sucker, ornbsp;Piercer, which the Creature thrufiis into thenbsp;Skin, to draw out the Blood or Humours itnbsp;feeds on, as it hath no Mouth that opens;nbsp;This Piercer, or Sucker, is judged to be-J*nbsp;feven hundred times flenderer than a Hairjnbsp;is contained in another Cafe within the firft,nbsp;and can be thruil out or drawn in at Plea-fure.

The Breaft is marked very prettily in the Middle, the Skin thereof tranfparent, and

* Vid. SwAMMERB, Hijl. Generale des In/eSles, p. 174. t Vid. Arc. Nat, Tom. II. p. 74.

N 4 nbsp;nbsp;nbsp;full

full of little Pits. From the under Part of it proceed fix Legs, each having five Joints,nbsp;their Skin refembling Shagreen, except towards the Ends, where it appears fmoother.nbsp;Each Leg terminates in two hooked Clawsnbsp;of unequal Length and Size, which it ufesnbsp;as we would a Thumb and middle Finger.nbsp;There are Hairs between thefe. Claws, asnbsp;well as over all the Legs.

On the Back of the Tail-part we may dif-cern fome Ring-like Divifions, Abundance of Flairs, and a Sort of Marks that look likenbsp;the Strokes of a Rod on one that has beennbsp;whipt. The Skin of the Belly feems likenbsp;Shagreen, and towards the lower End isnbsp;clear, and full of little Pits j at the Extremitynbsp;of the Tail are two little femi-circular Parts,nbsp;covered all over with Hairs, w'hich ferve tonbsp;conceal the Anus.

When the Loiife moves its Legs, the Motion of the Mufcles (which all unite in an oblong dark Spot in the Middle of its Breafl)nbsp;may be diftinguiflied perfedtly: and fo maynbsp;the Motion of the Mufcles in the Headnbsp;be when it moves its Horns. The Motionnbsp;of the Mufcles is alfo vifible in the feveralnbsp;Articulations of the Legs. W'e may like-wife fee the various Ramifications of the

Of the Louse. nbsp;nbsp;nbsp;179

Veins and Arteries (which are white) with the Pulie regularly beating in the Arteries.nbsp;But the moft furprizing of all is, the periftal-tic Motion of the Inteftines, continued fromnbsp;the Stomach along all the Guts down to thenbsp;Anus.

If a Loufe, when very hungry, be placed on the Back of the Fland, it will thruft itsnbsp;Sucker into the Skin, and the Blood maynbsp;be feen paffing in a fine Stream to the Fore-Part of the Head; where falling into anbsp;roundifh Cavity, it paffes again, in a likenbsp;Stream, to another circular Receptacle innbsp;the Middle of the Head from thence thro�nbsp;a fmaller Veffel to the Breaft and then tonbsp;a Gut that reaches to the hinder Part ofnbsp;the Body, where in a Curve it turns a littlenbsp;upwards.�In the Bread: and Gut the Bloodnbsp;is without Intermiffion moved with greatnbsp;Force, efpecially in the Gut; and that withnbsp;fuch a flrong Propulfion downwards, andnbsp;fuch a Contradlion of the Gut, as is amazing;nbsp;which continual and ftrong Adion of thenbsp;Stomach and Bowels upon the Food of thisnbsp;Creature, to further its Digeflion, is worthy to, be confidered,�In the upper Part ofnbsp;the crooked afcending Gut jufi: mentioned,nbsp;the propelled Blood hands hill, and feemsnbsp;to undergo a Separation : fome of it becoming clear and waterhh, while certain

little

If a Loufe be placed on its Back -f-, two bloody darkifh- Spots appear j the larger innbsp;the Middle of the Body, and the lefl'er towards the Tail. In the larger Spot a whitenbsp;phim or Bladder contradts arrd dilates upwards and downwards from the Head towards the Tail j the Pulfe of which is followed by a Pulfe of the dark bloody Spot,nbsp;in or over which the white Bladder feemsnbsp;to lie. This Motion of Syftole and Diallolenbsp;is feen beft when the Loife grows weak.nbsp;The white pulfing Bladder feems to be thenbsp;Heart, for on pricking it the Loufe inflantlynbsp;dies. In a large Loufe the Pulfation may benbsp;feen in the Back, but the white Film notnbsp;without turning the Belly Upwards. Thenbsp;lower darkilh Spot Dr. Harvey conjedturednbsp;to be the Excrements in the Guts.

Lice are not Hermaphrodites, as has er-roneoufly been imagined, but Male and Female. Mr. Leeuwenhoek difcoverednbsp;that the Males have Stings in their Tails,nbsp;but the Females none: and fuppofes thenbsp;fmartlng Pain they fometimes give arifesnbsp;from their Stinging, when made uneafy by

� Vid. Philc/opb. TrattfaCl. Numb. 102. f Vid. Dr. Power�s Obferu, 9.nbsp;j Arc. Nat, Tom. II. p. 77.

Preffure or otherwife j fince, if roughly handled, they may be feen .to thruft outnbsp;their Stings ; and as he felt little Pain ornbsp;Uneafinefs in the Sucker, or Piercer, thoughnbsp;leven or eight v/ere feeding on his Hand atnbsp;once. The Females lay Eggs or Nits, whencenbsp;young Lice come forth, perfedt m all theirnbsp;Members, and undergo no farther Changenbsp;but an Increafe of Size.

Mr. Leeuwenhoek, being defirous to learn the Proportion and Time of their Increafe, put two ¹ Females into a black Stocking, which he wore both Night and Dayjnbsp;and found that in fix Days one of them hadnbsp;laid fifty Eggs, and upon diffedting it, faw asnbsp;many more m the Ovary; whence h� concludes, that in twelve Days it would havenbsp;kid an hundred Eggs. Thefe Eggs hatching in fix Days (which he found to be theirnbsp;natural Time) would probably produce fiftynbsp;Males and as many Females: and thefe Fe-..nbsp;males coming to full Growth in eighteennbsp;Days, might each of them be fappofed, after quot;twelve Days more, to lay alfo an hundrednbsp;Eggs; which Eggs in fix Days farther (thenbsp;Time required to hatch them) might produce a younger Brood of five thoufand -f-.nbsp;So that in eight Weeks a Loufe may feenbsp;five thoufand of its own Defeendants j an

A Loufe may be difle�led eafily in a fmall Drop of Water, upon a Slip of Glafs thatnbsp;can be applied to the Microfcope; but without Water the Parts are very difficult to divide, and when feparated ffirivel and dry upnbsp;immediately. Thus five or fix Eggs of anbsp;full Size, and ready to be laid, may be foundnbsp;in the Ovary of a Female, with fixty ornbsp;feventy of different Sizes, but all much morenbsp;minute, as the Eggs are in the Ovary of anbsp;Hen. In the Male the Penis is remarkable,nbsp;and alfo the Tefles, whereof it has a doublenbsp;Pair; the Sting likewife deferves a curiousnbsp;Examination. Thefe Creatures avoid thenbsp;Light as much as poffible, and are impatientnbsp;of Cold. The Females, if fading, appearnbsp;very white, and even after feeding feem lefsnbsp;red than the Males, the Blood not appearingnbsp;fo plainly through their Veffels, from thenbsp;Multitude of their Eggs.

There is another Kind of Loufe found about uncleanly People, which, from itsnbsp;Shape, is called the Crab-Loufe. The Vermin adhering to and feeding on the Bodies,nbsp;of different Animals, though much, unlike

Of the Louse. nbsp;nbsp;nbsp;iSj

in Form and Size, are alfo commonly called Lice. Of thefe there are numberlefs Species,nbsp;feveral whereof we are obliged to Seignornbsp;Red I for giving us the Drawings of, at thenbsp;End of his Treatife de Generatione InfeSiorum,nbsp;whence Mr. Albin has taken them into hisnbsp;Book of Spiders: but few of thefe have beennbsp;fufficiently examined by the Microfcope, andnbsp;there are great Variety of other Kinds thatnbsp;are yet quite unknown.

Even Infe�ls are infefted with Vermin that feed on them and torment them. A Sort ofnbsp;Beetle, known by the Name of thp Loujynbsp;Beetle, is remarkable for Numbers of littlenbsp;Creatures that run about it nimbly from.nbsp;Place to Place, but will not be fhaken off.nbsp;Some other Beetles have Lice alfo, but ofnbsp;different Kinds.

The Earwig is troubled frequently with minute Infeits, efpecially juft under thenbsp;fetting-on its Head. They are white andnbsp;Alining like Mites, but much fmaller ; theynbsp;are round-backed, flat-bellied, and havenbsp;long Legs, particularly the two foremoft.nbsp;The fame has not been obferved on anynbsp;other Animal.

Snails of all Kinds, but chiefly the large ones without Shells, have many little Infers, extremely nimble, that live and feednbsp;upon them.

Numbers of little red Lice, with a very fmali Head, and in Shape refembling a Tqr-

toife, are often to be feen about the Legs of Spiders. Whilft the Spider lives they clingnbsp;clofely to it, but if it dies they leave it.

Whitidi Lice are frequently to be difcover-ed running very nimbly on Humble-Bees : I have feen them frequently on Ants ; manynbsp;Kinds are difcoverable on Filhes: Kirchernbsp;fays he has found Lice on Fleas and probably very few Creatures are free from them.

As fome may be delirous to know what Kinds of ^ Seignor-Redi has obfervednbsp;and given Drawhigs of, the following Lilfnbsp;is inferted to fatisfy their Curiolity. Licenbsp;found on the Hawk, three Sorts : on thenbsp;large Pigeon, the Turtle-Dove, the Hen,nbsp;the Starling, the Crane : on the Moor-Hennbsp;three Sorts: on the Magpie, the Heron,nbsp;the lefler Heron, the Swan, the Turkillinbsp;Duck, the Sea-Mew, the fmaller Swan : onnbsp;the w'ild Goofe two Sorts : on the Teal, thenbsp;Kaftrel, the Peacock, the white Peacock,nbsp;the Capon, the Crow, the white Starling :nbsp;on Sweetmeats and Drugs : on Men twonbsp;Sorts, namely, the common Loufe and the

* Redi calls the Vermin on Bealls Pediculi, or Lilt;e\ thof� on Birds Pulices, or Fleas. He fays every Kind of Bird hasnbsp;its particular Sort of Fleas, different from thofe of other Birds:nbsp;that all when firft hatched are white, but gradually acquirenbsp;a Colour like the Feathers they live among; yet remainnbsp;tranfparent enough for a good Microfcope to difcover the Motions of their Intellines : that the Crane has a white Sort,nbsp;marked as it were with Arabic Charafters : and that theirnbsp;Size is not proportioned to the Birds they breed upon, fornbsp;the little Black-Bird has Fleas as large as the Sman.

Crab-Loufe: on the Goat, the Camel, the -j- Afs, African Ram, the ^rican Hen:nbsp;on the Stag two Sorts, and on the Tiger.

THere is a little Animal, in Shape and Colour like a Loufe, that runs 1'wiftlynbsp;by Starts or Stops, and is commonly foundnbsp;on the Leaves and Covers of Books, ornbsp;amongft rotten Wood : it is called a Wood-Loufe, or Wood-Mite^ and is known almoftnbsp;to every body. The Eyes of this Creaturenbsp;are of a golden Colour, and can be drawn innbsp;or thruil out at Pleafure; the perifialtienbsp;Motion of the Bowels appears in it diftinft-ly, and, w'hat is ftill more wonderful, anbsp;Motion of the Brain is f�en.

I take this to be the Animal Mr.DERHAM calls the P'ediculus Pulfatorius, or Death-Watch (in Phil. Pranf. Numb. 291.) wherenbsp;he fays the Pediculus Pulfatorius and thenbsp;Scarabceus Sofiicephalus are the only two Infers that make regular clicking Noifes likenbsp;the Beat of a Pocket-Watch.

t Aristotle in his Hijiory. cf Animals, and Pliny on his Authority, afferss, tYidXAJfes and Sheep are free from Vermin ; but Red* proves they are both lailiafcen as to the Ajs ;nbsp;and as to t\s^Sheep, everyShepheid-Boy is able to confute them.

I, The Louje of a Lion, refembles that of the T'iger in Shape, but is larger, and of a brighter red. Vid. Redi Experim.nbsp;�circa General, In/etl, p. 312. amp; feq.

^ nbsp;nbsp;nbsp;c 186 i

CHAP. XXIIi.

By Mites are conlmonlyunderftood the minute Creatures found in great Abundance in Cheefe that is decaying. To thenbsp;naked Eye they appear like moving Particlesnbsp;of Duft; but the Microfeope difeovers themnbsp;to be Animals perfedl in all their Members^nbsp;having as regular a Figure, and performingnbsp;all the neceffary Offices of Life in as orderlynbsp;a Manner, as Creatures that exceed themnbsp;many millions of Times in Bulk.

They are cruftaceous * Animals, and ufu-ally tranfparent. The principal Parts of them are, the Head, the Neck, and Body. Thenbsp;Head is fmall in Proportion to the Body,nbsp;with a ffiarp Snout, and a Mouth that opensnbsp;and Ihuts like a Mole�s. They have twonbsp;little Eyes, and are extremely quick-lighted;nbsp;for if you touch them once with a Pin ornbsp;other Inllrument, you�ll perceive how readily they avoid a fecond Touch. Some havenbsp;fix Legs, and others eight which provesnbsp;them of different Sorts, tho� in every refpeftnbsp;befides they appear alike. Each Leg has fixnbsp;Joints, furrounded with Hairs, and two little

Claws

Claws at the Extremity thereof, which can eaiily take up any thing. The hinder Partnbsp;of the Body is plump and bulky, and endsnbsp;in an oval Form, with a few exceeding longnbsp;Hairs iffuing therefrom. Other Parts of thenbsp;Body and Head are alfo thinly befet withnbsp;long Hairs.

Thefe Creatures are Male and Female. The Female lay Eggs whence (as in Licenbsp;and Spiders) the young ones iffue forth withnbsp;all their Members perfedl, though moil exceedingly minute: but,notwithftandingtheirnbsp;Shape does not alter, they call their Skinsnbsp;feveral Times before they attain their fullnbsp;Growth.

They may be kept alive many Months between two concave Glades, and applied tonbsp;the Microfcope at Pleafure j and by oftennbsp;looking at them, many curious Particularsnbsp;will be difcovered. They may thus frequently be feen in Coitu^, conjoined Tail to Tail;nbsp;for though the Penis of the Male be in thenbsp;Middle of the Belly, it turns backwards likenbsp;that of the Rhinoceros. The Coitus is performed with an incredibly fwift Motion.nbsp;Their Eggs in warm Weather hatch innbsp;twelve or fourteen Days; but in Wintertime, and cold Weather, not under feveral

Weeks. It is not uncommon to lee the young ones llruggling to get clear of thenbsp;Egg-fhell# which fometimes they are a Daynbsp;about.

The Diameter of a Mites Egg feems equal to the * Diameter of the Hair of a Man�snbsp;Head; and fix hundred fuch Hairs are aboutnbsp;equal to the Length of an Inch. Suppolingnbsp;then a Pigeon�s Egg is three Quarters of annbsp;Inch in Diameter, four hundred and fiftynbsp;Diameters of a Mite's Egg are but equal tonbsp;the Diameter of the Egg of a Pigeon ; andnbsp;confequently, if their Figures be alike, wenbsp;muft conclude that ninety-one millions annbsp;hundred and twenty thoufand Eggs of a Mitetnbsp;are not larger than one Pigeon�s Egg.

Mites are moll voracious Animals j for they devour not only Cheefe, but likewifenbsp;all Sorts of dried Fifh orFlefh, dried Fruits,nbsp;Grain of all Sorts, and almoft every thingnbsp;befides that has a certain Degree of Moiflurenbsp;wdthout being over-wet: nay, they maynbsp;often be obferved preying upon one another.nbsp;In eating, they thrull one Jaw forwards andnbsp;the other backwards alternately, wherebynbsp;they appear to grind their Food j and afternbsp;they have done feeding, they feem to munchnbsp;and chew the Cud.

Thefe are the Vermin that find a Way into the Cabinets of the Carious, and eat up their fine Butterjlies and other choice InfeBs,nbsp;leaving nothing in their Stead but Dult andnbsp;Ruins. The heft Method of preventing thisnbsp;is, to keep the Drawers or Boxes continuallynbsp;fupplied with Camphirct whole hot and drynbsp;Effluvia penetrate, fhiivel up, and dellroynbsp;the tender Bodies of thefe little inifchievousnbsp;Plunderers.

It mufi; however be remembered, that there are feveral Species of Mites, whichnbsp;differ in fome Particulars, though their general Figure and the Nature of them be thenbsp;fame. For Inftance, the Mites * in Malt-Duft and Oatmeal-Duft are nimbler thannbsp;Cheefe-Mites, and have more and longernbsp;Hairs. The Mites amongft Figs refemblenbsp;Scarabs, have two Feelers at the Snout, andnbsp;two very long Horns over them, with threenbsp;Legs only on each Side, and are more flug-gitli than thofe in Malt. Mr. Leeuwenhoek obferved fome Mites on Figs to havenbsp;longer Hairs than he had feen on any othernbsp;Sorts; and upon Examination found thofenbsp;Hairs were fpieated, or had other little Hairsnbsp;iiTuing from their Sides : whence he imagined they might be jointed at the littlenbsp;Diftance where thefe Hairs come forth. He

O 2 nbsp;nbsp;nbsp;had

had alfo feen the like Hairs on other Mites, though very feldom. Mr. Hook defcribesnbsp;a Sort of thefe Animals, which he termsnbsp;wandering Mites ¹, as being to be found innbsp;every Place almoft where they can getnbsp;Food.

Happening fome Years ago to look into an empty white Gallipot, I fancied it wasnbsp;dufty } but, on a nearer View, perceivingnbsp;the Particles to move, I examined them bynbsp;the Mtcrofcope, and difcovered what I hadnbsp;taken for Duft to be Swarms of thefe wandering Mites, which were tempted andnbsp;brought thither by the Smell of fomenbsp;Caviere that had been in the Gallipot anbsp;few Days before.

The Mite is exceedingly tenacious of Life; I have kept them in my Glafles Months together, even without Food j and Mr. Leeuwenhoek fays, one he ftuck upon a Pinnbsp;before his Microfcope -j- lived in that Condition eleven Weeks.

This well-known little Creature is covered all over with black hard Ihellynbsp;Scales, Plates, or Divifions, curioufly jointed,nbsp;and folded over one another in fuch a Manrnbsp;ner as to comply with all the nimble Motions and Activity of the Animal. The Scalesnbsp;are curioufly polhhed, and befet about thenbsp;Edges with long Spikes, in the moll: beautiful and regular Order poflible. Its Necknbsp;is finely arched, and much refembles thenbsp;Form of a Lobfter�s Tail. The Plead is verynbsp;extraordinary} for from the Snout-part thereof proceed its two Fore-Legs, and betweennbsp;them lies the Piercer or Sucker wherewith itnbsp;penetrates the Skin of other living Creaturesnbsp;and draws out its Food. It has two largenbsp;beautiful black' Eyes, and a Pair of littlenbsp;Horns or Feelers. Four other Legs are joined on at the Bread:, fo that it has fix in all jnbsp;which, when it leaps, fold Ihort one within another, and, exerting their Spring all atnbsp;the fame Inflant, carry the Creature to anbsp;furprifing Diftance. The Legs have manynbsp;Joints, are very hairy, and terminate in twonbsp;long (harp hooked Claws, as may be feennbsp;Fig. VI, Plate XIII.

O 3 nbsp;nbsp;nbsp;The

The Flea's Piercer or Sucker is lodged be-^ tween its Fore-Legs, and includes a Couplenbsp;of D irts or Lancets, which, after the Piercernbsp;has made an Entrance �¹, are probably thruffcnbsp;farther into the Flefh, to make the Flood,nbsp;flow from the adjacent Parts, that it may benbsp;fucked up; and feems to occafion that roundnbsp;red Spot, with a Hole in the Center of it,nbsp;wiiich we commonly call a Flea-Bite. Thisnbsp;Pierctr, its Sheath opening fideways, andnbsp;the two Lancets within it, are very difficultnbsp;to be feen, -f- unlefs the two Fore-Legs, between which they are ufually folded in andnbsp;concealed from View, be cut off clofe to thenbsp;Head: for a F/ea rarely puts out its Piercernbsp;except at the Time of Feeding, but on thenbsp;contrary kftcps it clofely folded inwards ; thenbsp;heft Way therefore of coming at it is, bynbsp;cutting of the Head firft, and then thenbsp;Fore-Legs ; fince in the Agonies of Deathnbsp;it may ealily be managed, and brought before the Microjcope.

Fleas are Male and Female, and lay Eggs as well as Lice and Mites ; but are extremelynbsp;different in ali the Progrefs of their Lives be-Edes, f affing thro� the fame Changes exa�llynbsp;as the Stlkwonn does. They depofit theirnbsp;Eggs at the Roots of the Hair of Cats, Dogs,

and other Animals, flicking them fafl thereto by a Kind of glutinous Moiflure. When the Eggs hatch, not perfed: Fleas, but littlenbsp;Worms or Maggots, whofe Bodies have fe-veral annular Divifions thinly covered withnbsp;long Hairs, come out of them, and feed onnbsp;the Juices of the Animal, whereto they clofe-ly adhere Thefe Maggots are very brifknbsp;and nimble; but if touched, or under anynbsp;Fear, roll themfelves up on a fudden in anbsp;round Figure, and continue motionlefs fornbsp;fome Time; after which they flowly opennbsp;themfelves and crawl away, as Caterpillarsnbsp;do, with a lively and fwift Motion.

When the Time of their Change approaches, they conceal themfelves as much as poffible; eat nothing, lie quiet, and feemnbsp;as if dying ; but if viewed with the Micro-fcope, will be found, with the Silk or Webnbsp;that comes out of their Mouth, weaving anbsp;Covering or Bag round them, whofe Intidenbsp;is as white as Paper, though without it always appears foiled with Dirt. In this Bagnbsp;they put on the Chryfalis or Aurelia Form,nbsp;and become Milk-white ; but two or threenbsp;Days before they break from this Prifon,nbsp;their Colour darkens, they acquire Firm-nefs and Strength, and as foon as they ifluenbsp;from the Bag are perfeSl Fleas, and able tonbsp;leap away.

O 4

It has been difcovered, by putting the Eggs of Fleas in a fmall Glafs Tube, andnbsp;keeping it conftantly warm in one�s Bofom,nbsp;that, in the midft of Summer, they hatchnbsp;in four Days : then, feeding the Maggotsnbsp;\vith dead Flies, which they fuck greedily,nbsp;in eleven Days they come to the full Perfection of their reptile State : when the Maggotnbsp;fpins its Bag, and in four Days more changesnbsp;into a Chryfalis j after lying in which Condition nine Days, it becomes a perfeB Flea.nbsp;It is then immediately capable of Coition,nbsp;and in three or four Days lays Eggs. Sonbsp;that in * twenty-eight Days a Flea maynbsp;come from the Egg itfelf, and propagate itsnbsp;Kind : and their vaft Increafe will not feemnbsp;fo great a Wonder, if we confider, thatnbsp;from March to December there may be fevennbsp;or eight Generations of them. After havingnbsp;laid their Eggs they foon die, as all Creaturesnbsp;do^hat undergo fuch like Changes.

By keeping Fleas in a Glafs Tube corked at both Ends, but fo as to admit frefh Air,nbsp;their feveral Adlions may be obferved, andnbsp;particularly their Way of coupling, w'hich isnbsp;performed Tail to Tail, the Female (whichnbsp;is much the larger) Handing over the Male.nbsp;They will alfo be feen to lay their Eggs, notnbsp;all at once, but ten or twelve in a Day for

A Difl'eftion of the Flea may be efteil-ed after the fame Method as that of the Loufe, that is, in Water : the ¹ Stomach andnbsp;Bowels, with their periftaltic Motion, maynbsp;plainly be diftinguifhed, and alfo the -f-Teftesnbsp;and Penis, together with Veins and Arteriesnbsp;minute beyond Conception. Leeuwenhoek affirms, that'hehas likewife difcoverednbsp;innumerable Animalcules ffiaped like Serpents in the Semen majculinum of a Flea.

Two Things in this Creature deferve our Confideration, to wit, its furprifing Agility,nbsp;and its prodigious Strength, whereby it isnbsp;enabled to leap above an hundred Times itsnbsp;own Length ; as has been proved by Experiments. What vigorous Mufcles ! and hownbsp;weak and fluggiffi, in Proportion to its ownnbsp;Bulk, is the Horfe, the Camel, or the Elephant, if compared with this puny Infe�t!

CHAP. XXV.

Every body is fo well acquainted with the general Form of a Spider, evennbsp;without the Affiftance of -x Microfcope, thatnbsp;I {hall fpend no Time in the Defcnption ofnbsp;it; but proceed to give an Account of fomenbsp;Particulars in this Animal which are difco-verable only by that Infbrument.

As a Fly (the Spider ^ natural Prey) is extremely cautious and nimble, and comesnbsp;ufually from above, it was neceifary thenbsp;Spider fliould be furnilhed with a quicknbsp;Sight, and an Ability of looking upwards,nbsp;forwards, and fideways, at the fame Time :nbsp;and the Microjcope lliews, that the Number, Strudlure, and Difpofition of its Eyesnbsp;are wonderfully adapted to ferve all thefenbsp;Purpofes.

Moll Spiders have eight Eyes * : two on the Top of the Head or Body (for there isnbsp;no Divifion between them, a Spider^ havingnbsp;no Neck) that look diredtly upwards �, twonbsp;others in Front, a little below thefe, to dif-cover all that paifes forwards j and on eachnbsp;Side a couple more, one whereof points iide-

A nbsp;nbsp;nbsp;ways

ways forwards, and the other fideways backwards ; fo that it can fee almoft quite round it. All Kinds of them have not, indeed, anbsp;like Number of Eyes; for we find ten innbsp;fome, in others only eight, fix, or four; andnbsp;in the Field, Long-Legs, or Shepherd-Spider,nbsp;no more than two. But whatever thenbsp;Number be, they are immoveable andnbsp;tranfparent; are fituated in a mod: curiousnbsp;Manner, and deferve the drided Examination. The bed Way of viewing them is, tonbsp;cut off the Legs and Tail, and bring only thenbsp;Head-part before the Microfeope.

All Spiders have eight Legs, which they employ in walking, and two Arms or fhorternbsp;Legs near the Mouth, that aflid in takingnbsp;their Prey. They appear thickly befet withnbsp;Hair, have each fix Joints, and end withnbsp;two hooked Claws, ferrated, or havinsr

Teeth like a Saw on their Infide, whereby they cling fad to any thing; and at a littlenbsp;Didance from theie Claws a Sort of Spurnbsp;dands out, without any Teeth at all. Seenbsp;Fig. VII. Plate XIII.

But the dreadful Weapons wherewith the $pider feizes and kills its Prey are a Pair ofnbsp;fharp crooked Claws or Forceps (by fome,nbsp;tho� very improperly, called Stings), in thenbsp;Fore-part of its Head. The Scolopendra,nbsp;or Indian Millepss, and feveral other In-feds, have Wea|)ons of the like Form, and

ferving to the fame Purpofe. Thefe Claws or Pincers hand horizontally and are, whennbsp;not made ufe of, concealed in two Cafesnbsp;contrived for their Reception : into whichnbsp;they fold like a Clafp-knife, and there lienbsp;between two Rows of Teeth, that are like-wife employed to hold fafb its Prey. Thisnbsp;Apparatus is better fhewn than defcribed :nbsp;See Fig. VIII.

Mr. Leeuwenhoek informs us, ¹ that each of thefe Claws or Pincers has a fmallnbsp;Aperture or Slit near its Point, as in a Viper�snbsp;Tooth j thro� which he fuppofes a poifon-ous Juice is injedled into the Wound itnbsp;makes, occafioning Death to Flies and othernbsp;Infedls. But Dr. Mead, in his moft excellent 'Effay on Poifons, believes this to be anbsp;great Miftake having not been able to dif-cern any Exit or Opening, tho� he viewednbsp;thefe Parts feveral Times with a very goodnbsp;Microfcope. And he was the more confirmednbsp;in this Opinion, by examining a Claw of thenbsp;great American Spidery defcribed by Pi so,nbsp;and called Nhamdu, given him by Mr. Pe-TivER j which being about fifty Timesnbsp;bigger than that of any European Spider, ifnbsp;there had been any Slit in it, he doubtednbsp;not his Glafs would have difcovered it j butnbsp;yet he found it to be quite folid. Befides,

after repeated Trials, he plainly faw that � nothing dropped out of the Claws, whichnbsp;� were always dry while the Spider hit; butnbsp;� that a Ihort white Probofcis was at thenbsp;� fame Time thruft out of the Mouth, whichnbsp;inftilled a Liquor into the Wound.� Andnbsp;he farther obferves, that the Quantity ofnbsp;Liquor emitted by our common Spiders,nbsp;� when they kill their Prey, is vifibly fonbsp;great, and the wounding Weapons fonbsp;� minute, that they could contain but anbsp;� very inconfiderable Portion thereof, if itnbsp;** were to be difcharged that Way,�

Spiders frequently caft their Skins, which may be found in Cobwebs, perfedlly dry andnbsp;tranfparent; and from fuch Skins the Forceps or Claws (for they are always �hed withnbsp;the Skin) may eafier be feparated, and examined with more Exad:nefs, than in a livingnbsp;Spider: for they commonly appear Ipreadnbsp;out fairly to View, and, by their Tranfpa-rency, every minute Part is feen with muchnbsp;Diftindtnefs. But neither this Way, nornbsp;any other, have I been ever able to difcernnbsp;the Aperture Mr. Leeuwenhoek fpeaksnbsp;of.

The Contexture of the Webs of Spiders, and their Manner of weaving them, are farther Difcoveries of the Microfcope; for thatnbsp;informs us, that the Spider has five little

Teats or Nipples near the Extremity of the Tail, whence a gummy Liquor proceeds^nbsp;which adheres to any thing it is prelTednbsp;againh:; and being drawn out, hardens in^nbsp;flantly in the Air, and becomes a String ornbsp;Thread, ftrong enough to bear five or fixnbsp;Times theWeight of xhtEpider^ Body. Thisnbsp;Thread is compofed of feveral finer onesnbsp;that are drawn out feparately, but unite together two or three Hairs Breadth diftantnbsp;from the Body of the Epider. The Threadsnbsp;are finer or coarfer, according to the Bignefsnbsp;of the Spider that fpins them. Mr. Leeuwenhoek computes, that an hundred of thenbsp;fineft Threads of a full-grown Epider arc notnbsp;equal to the Diameter of the Hair of hisnbsp;Beard; and, confequently, if the Threadsnbsp;and the Hair be round, ten thoufand fuchnbsp;Threads are not bigger than fuch an Hair.nbsp;He calculated farther, that when young Epi-�nbsp;ders firft begin to fpin, four hundred of themnbsp;are not larger than one that is full-grown;nbsp;and therefore the Thread of fuch a littlenbsp;Spider is fmaller by four hundredTimes thannbsp;the Thread of a full-grown one : allowingnbsp;which, four Millions of a young Spider ^nbsp;Threads are not fo big as the fingle Hair ofnbsp;a Man�s Beard

Of Spiders.

The Eggs of fome Spiders are very pleasant Objedls, being round at one End and flattifh at the other, with a Depreffion in thenbsp;Center of the flatthh End, and a yellowiflinbsp;Circle round it. Their Colour is a blueiflinbsp;White, like counterfeited Pearl; and whennbsp;they hatch, the little Spiders come out perfectly formed, and run about very nimbly.nbsp;The Female depolits her Eggs, to the Number of five or fix hundred, in a Bag ftronglynbsp;compofed of her own Web, which file either carries under her Belly, and guardsnbsp;with the greatefi; Care, or elfe hides in fomenbsp;fafe Recefs. As foon as the Eggs are hatched, the minute Spiders appear very agreeablynbsp;in the Microfeope.

It has been before obferved, that the Current of the Blood may be feen in the Legs and Body of this Creature ; and the judicious Obferver will difeover many othernbsp;Wonders in the DifieCtion and Examinationnbsp;of its feveral Parts, which it would be tire-fome for me to dwell on here. I cannot,nbsp;however, conclude this Head without pointing out two or three Kinds of Spiders asnbsp;particularly worth Notice.

There is a little white Field Spider, with fliort Legs, found plentifully among newnbsp;Hay, whofe Body appears like white Amber, with black Knobs, out of each whereof

202 nbsp;nbsp;nbsp;Of Spiders.

of grow Prickles like Whin-Pricks. Some have fix, fome eight Eyes, that may be dif-tinftly feen, quick and lively : each Eye hasnbsp;a Violet-blue Pupil, clear and admirable,nbsp;furrounded by a pale yellow Circle

The wandering or 'j- hunting Spider, who fpins no Web, but runs and leaps by Fits,nbsp;has two Tufts of Feathers fixt to its Fore-Paws, which well deferve being placed before the Microfcope : the Variety and Beautynbsp;of Colouring all over this little Creaturenbsp;afford likewife a mofl; delightful View.

The J Long-Legs, Field, or Shepherd-Spider is a moft wonderful Creature : It has two Fore-Claws at a great Diftance fromnbsp;the Head, tipped with Black like a Crab�s,nbsp;that open and fhut in the Manner of a Scorpion�s, and are Saw-like, or indented, onnbsp;the Infide.�Cut all the Legs from this Spider, and place it before the Microfcope, andnbsp;you will difcover, that the Protuberance onnbsp;the Top of the Back is furnifhed with twonbsp;fine Jet-black Eyes.

The little red Spider that creeps on the Barks of Trees fhould alfo not be negledled.

� 'Dr.Vovitv.'s Micro/ccp. Ob/er'vat. p. 13. f Hook�s Microg. p. zoo. J Ibid. p.

C FI A p.

The Produdtion of this Creature is from an Figg, depofited by its Parent uponnbsp;the Waters, which firft becomes a Worm ornbsp;Maggot, then a very odd aquatic Animal (de-fcribed page 88.) and afterwards a Gnat.

The particular Beauties of it cannot poffi-bly be difcovered without the Microfcope-, but by the Affiftance of that Inftrument, it appears to be adorned by Nature in a moiienbsp;extraordinary Manner than moft other livingnbsp;Creatures are. Its Tail-part is covered overnbsp;with Feathers, moft exquifitely difpofed innbsp;Rows of different Colours, but yet perfedllynbsp;tranfparent. The Breaft ¹ (which is cruf-taceous) is bedecked with little ftiff Hairsnbsp;or Briftles, inftead of Feathers j and fromnbsp;thence fix hairy Legs proceed, with fix Jointsnbsp;to each, and at the End two little Claws.nbsp;The Feet are all over feathered in a Mannernbsp;refembling the Scales of Fifties, with Abundance of little black Hairs amongft them,nbsp;appearing ftubborn like Hogs Briftles. Itsnbsp;Wings are encompaffed with a Furbelow ofnbsp;long Feathers ; and the Veins or Ribs that

ferve to ftrengthen them are alfo either fea---thered or fcaled. Between thefe Ribs an exceeding thin tranfoarent Membrane is ex-tended, hull of little black iharp-pointed H airs, that are ranged every where with thenbsp;utinoft Regularity. But as there are * different Sorts' of Gnats, their Wings are alfonbsp;very diferent, fome having a Border of longnbsp;Feathers, others of ihort ones, and othersnbsp;none at all; the Rib-work of the Wings,nbsp;likewife, in fome is feathered, in fome fcaled,nbsp;and in fome hefet with Prickles.

But the moll wonderful Part of this Creature is its Head ; as it contains the Horns, the Sting or Sucker, and the Eyes. Thenbsp;Horns of the brufh-hor?ied or Male Gnat arenbsp;a m.ofl charming Objedt : it has two Pair,nbsp;one whereof is furrounded, at little Diftances,nbsp;with long Hairs iifuing out circularly j eachnbsp;Circle leflening more than other as it ftandsnbsp;nearer the Extremity of the Horns : and thenbsp;Whole together exadlly reprefenting the Figure of the Plant called Equifetim or Horfe-~nbsp;tail. The other Pair is longer and muchnbsp;thicker than the foregoing, and hairy from'nbsp;End to End. In the great-bellied or Femalenbsp;Gnat, the firft Pair of Horns, though of the

� Mr. Derham obferved near forty different Species of Gfiats about the Place where he lived, which was Upminjiifnbsp;in F,J]sx, Vide Ph^ico-Tbakgy, p. 3,78.

fame

iarne Figure as the Male�s, has Kaip not near fo long, and the lecond Pair is thortsrnbsp;than the fiiTt by at leaft three Parts in four.

Th� Pierce^-, Sting, or Sucker, is a Cafe covered with long Scales, that lies concealednbsp;under the * G?iafs Throat vvhen nor madenbsp;life of. The Side opens, and four Darts arenbsp;thruft out thence occafionaliy �, one whereof (minute as it is) ferves for a Sheath tonbsp;the other three. The Sides of them are extremely iliarp, and they are barbed or indented towards the Point, whofe Finenefs isnbsp;inexprefilble, and fcarcely to be difcenied bynbsp;the greateft Magnifier. When thefe Dartsnbsp;are thrufi: into the Flefli of Animals, eithernbsp;fucc�flively or in Conjunilion, the Bloodnbsp;arid Humours of the adjacent Parts muftnbsp;flow to and caufe a Tumour about thenbsp;Wound, whofe little Orifice being doled upnbsp;by the Compreffion of the external Air, cannbsp;afford them no Outlet. When a Gnat findsnbsp;aiiy tender juicy Fruits or Liquors, me fucksnbsp;up what the likes through the outer Cafe,

feverely, then flieaths her Weapons in their Scabbard, and through them fucks up thenbsp;Juices the finds there. The Pain they caufe

Of the Gnat.

is only while they are entering, and continues not when the Gnat is fucking : nor is its Stinging out of Revenge, but from merenbsp;Neceffity to obtain a proper Suftenance.

A Gnat�s Eyes, which form the greateft Part of its Head, are pearled, or compofednbsp;of many Rows of little femicircular Protuberances ranged with the utmoft Exactitude.nbsp;What thefe Protuberances are, and the Pur-pofes whereto they ferve, will be explainednbsp;when we come to treat of the 'Eyes of Infers,

The Motion, of the Itneftines may be feen in the tranfparent Parts of this Animal; andnbsp;upon DiffeCtion many curious Difcoveriesnbsp;may be made. Mr. Leeuwenhoek fays,nbsp;he found in the ¹ Semen of the Male num-berlefs Animalcules fmaller than thofe innbsp;Fleas, and in the Female a furprizing Quantity of Eggs. And, indeed, the Spawn ofnbsp;this Tnfeft is amazingly great in Proportionnbsp;to its Size, being feen floating on the Watersnbsp;(though always f^aftened to fomething to prevent its fwimming away) fometimes abovenbsp;an Inch in Length, and half a quarter in Dia-�meter; the Eggs (each of which has a little

black Speck) being placed in exadt Order, and kept together by a Sort of Jelly or glewynbsp;Matter, which the minute Maggots, whennbsp;hatched, carry down with them to the Bottom, and thereby cement together the fmallnbsp;Particles of'Earth or Sand that form theirnbsp;Cells or Cafes.

Another creature that undergoes a ^ like Change, is the Ox-Fly, Dun-Fly,nbsp;or Gad-Bee, an Infedl very troublefome tonbsp;Cows and Horfes.

This, like the Gnat, has a long Probofcis, with a (harp Dart or Darts Iheathed therein.nbsp;The Ufe of thefe Darts is to penetrate thenbsp;Flefh of Animals, and feed on their Blood jnbsp;whereas the Probofcis can only ferve to fucknbsp;the Juices, Honies, or Dews, from Fruits,nbsp;Flowers, or the Leaves of Plants: and Providence feems to have kindly furnifhed itnbsp;with this tw'o-fold Inftrument, that if onenbsp;Sort of Provifion fails it may be able to fub-fift on the other. It is worth Enquiry, whether Lice, Fleas, Houfe-Bugs, amp;c, are notnbsp;alfo provided for the fame Purpofe.

P 2 nbsp;nbsp;nbsp;The

The Eggs of this Infed: are depofited in th� Watets, and produce an extraordinarynbsp;Kind of little Worm or Maggot, the Extremity of whofe Tail is incircled with move-*nbsp;able Hairs, which, being expanded on thenbsp;Surface of the Water, enable it to float along,nbsp;as * in plate VII. Fig. XiII. a. When itnbsp;would defcend towards the Bottom, thefenbsp;Hairs are made to approach each other in annbsp;oval Form, and incloie a little Bubble of Air^nbsp;hy Means whereof it is able to rife again ;nbsp;and if this Bubble elcapes, as fometimes itnbsp;wdll, the Infedl immediately fqueezes out ofnbsp;its owm Body another like Bubble to fupplynbsp;the Place thereof. The Maggot, as defcend-*nbsp;iiig, is flrewn Fig. XIII. b. Its Snout hasnbsp;three Divifipns, whejice three little pointednbsp;Bpdies are thrufi out, in continual Motion,nbsp;like the Tongues of Serpents.

Thefe Maggots frequently to he met vrith in Water taken from the Surface ofnbsp;Ditches. The Motion of their Interlines isnbsp;perfedly fingular and diflinguitlrable, andnbsp;they are Objeds well deferving our particular Obfervation.

C H A p.

CHAP. XXVIIL

TH E farp and penetrating Infryanents wherewith the Tails of Bees, Wafps,nbsp;Hornets, Ants, and fome other Infe�ls arenbsp;armed, I diftinguifli by the Name of Stings-,nbsp;being Weapons given them by Nature tonbsp;defend themfelves and offend their Enemies;nbsp;whereas the 'Trunk or Probfcis which Gnats,nbsp;Fleas, Lice, and many other Kinds carry innbsp;their Mouth, though it may be equally fliarp,nbsp;is not intended as an Inftrument of Revenge,nbsp;but for procuring and fucking in their Food;nbsp;and therefore when fuch Creatures bite ornbsp;Ring us, as we term it, we muft not imaginenbsp;they do fo out of Anger, but from Neceffity.nbsp;Squeeze or Ifrike a Bee or Wafp, it inftant-ly puts forth its Sting; but no Provocationnbsp;�can urge a Flea or Gnat to bite; on thenbsp;contrary, when difturbed or hurt, they drawnbsp;in their Frobofeis inftead of thrufting it out,nbsp;and never make ufe of it hut when theynbsp;think themfelves perfectly fafe and quiet.nbsp;There is befdes this farther Difference : anbsp;Sting injects a venomous Liquor into thenbsp;Wound it makes; but 2. Frobofeis fucks ornbsp;straws out the Blood and Humours from it.

P 4 nbsp;nbsp;nbsp;As

As the Strudture and Contrivance of moil Stings are nearly alike, by defcribing one thenbsp;reft will be underftood. I fhall, therefore,nbsp;give a brief Account of the S/ing of a Bee,nbsp;as difcovered by the Microfcope.

TH E Sting of a Bee is a horny Sheath or Scabbard that includes two beardednbsp;Darts. This Sheath ends in a ftiarp Point:nbsp;near the Extremity v/hereof a Slit opens,nbsp;through which, at the Time of Stinging, twonbsp;bearded Darts are protruded beyond the Endnbsp;of the Sheath �, one whereof, being a littlenbsp;longer than the other, fixes its Beard firft �,nbsp;but the other inftantly following, they penetrate alternately deeper and deeper, takingnbsp;hold of the Flefti with their Hooks, till thenbsp;whole Sting becomes buried in the Wound:nbsp;and then a venomous Juice is ifije�led, thro�nbsp;the fame Sh�ath, from a little Bag at thenbsp;Root of the Sting, which occafions an acutenbsp;Pain, and a Swelling of the Part, continuingnbsp;fometimes feveral Days. This is beft prevented by enlarging the Wound immediately, to give it fome Difcharge.

Mr. Derham fays, he counted in the Sting of a Wafp eight Beards on the Side ofnbsp;each Dart, fomewhat like the Beards of Fifh-hooks ; and I have obferved the fame Number in that of a Bee. When thefe Beards arenbsp;ftruck deep in the Flefli, if the woundednbsp;Perfon ftarts before the Bee can difengagenbsp;them, (he leaves her Sting behind flickingnbsp;in the Wound : but if he has Patience tonbsp;ftand quiet till fhe brings the Hooks clofenbsp;down to the Side of the Darts, fhe withdrawsnbsp;her Weapon, and the Wound becomes muchnbsp;lefs painful. A Wafp is not fo liable as anbsp;Bee to leave its Sting behind, the Beards ofnbsp;it being rather fhorter, and the Animalnbsp;ftrongcr and more nimble ¹.

To view the Sting of a Bee by the Mi-crofcope, cut off the End of its Tail, and then touching it with a Pin or Needle, itnbsp;will thruft out the Sting and Darts, whichnbsp;may be fnipt off with a Pair of Sciffars andnbsp;kept for Obfervation. Alfo if you catch anbsp;Bee in a Leather Glove, its Sting will be

left therein, being unable to difengage its Hooks from Leather: and when it is quitenbsp;dead, which it will not be till after feveralnbsp;Hours, you may, by Care and Gentlenefs,nbsp;extract it with its Darts and Hooks. Bynbsp;Squeezing the Tail, pulling out the Sting,nbsp;and preffing it at the Bottom, you may like-wife iorce up the Darts; but without fomenbsp;Practice this will be a little difficult.

The Bag containing the poifonous ]uicc may ealily be found at the Bottom of thenbsp;jSting, and examined, being commonly pulled out with it : and, by letting the Beenbsp;ftrike its Sling upon fome hard Body, enoughnbsp;of the faid juicemay be obtained to put uponnbsp;a Slip of Glafs, in order to view the Saltsnbsp;floating therein at firft^ and afterwards ffioot-ing into Cryftals.

'OW far the Sting of a Scorpion is of a __like Structure with that of a Bee, I never had the Opportunity of examining, as none of them are brought alive to 'Englandnbsp;but the Curious that go abroad to hot Countries, where they are produced, would donbsp;well to obferve particularly, whether a Dart

The Opinions of Authors are very different as to this Creature�s having or not having any Opening in its Sting, through which, a Poifon iffues into the Wound it makes.nbsp;Galen fays, there is none; Pliny, Ter-TULLiAN,AiLiAN,ALDRovAND,and Othersnbsp;affert, on the contrary, that there is. But Inbsp;think this Matter is let in the trueft Lightnbsp;by Signior Redi, that diligent Naturaliff,nbsp;who took the Pains to examine Scorpionsnbsp;brought from Tunis, from Egypt, andnbsp;from Italy, in order to difcover this Aperture, with two of the bell Aiicrofcopes innbsp;the Mufeum of the Grand Duke of Tuscany, one v/hereof was made at Rome,nbsp;and the other in England : but, thoughnbsp;thefe Glaffes were excellent, he was unablenbsp;.to difcern the lead: Perforation. However,nbsp;not fatisfied with only viewing them, he endeavoured by Preffure to fqueeze from thenbsp;Cavity of the Sting any Liquor it might contain ; but he found it fo hard and horny,nbsp;that Squeezing could have no Effeft. He,nbsp;moreover, caufed a Scorpion to ftrike on anbsp;Plate of Iron, but no Moiflure appearednbsp;thereon ; fo that he began to conclude Galen�s Opinion right : when he difcovered,nbsp;accidentally, an exceeding fmali and almoflnbsp;invilible L)rop of ^hite Liquor upon the

Sting* j which convinced him that ^Elian fays true, where he afferts, that the Perforation in a Scorpion s Sting is fmall beyondnbsp;the Poffibility of being feen. And fuch anbsp;Drop he frequently faw afterwards, in thenbsp;Progrefs of his Experiments, on the Stingsnbsp;of feveral Scorpions, at the Time of theirnbsp;Striking ; which Drop entering the Wound,nbsp;produced the mofl: fatal Effedts �f'.

What a virulent and furprizing Poifon muft this be! that in fo very minute a Quantity can contaminate the whole Mafs of thenbsp;Fluids, and bring on fudden Death, not onlynbsp;in Man, and other fmaller Creatures, butnbsp;even in Lions, Camels, and Elephants, asnbsp;we are aflured it will! How fubtle, hownbsp;penetrating, how divifable, mull the component Particles of this little Speck of Venomnbsp;be ! and how ftrong a Proof it affords, thatnbsp;the greateft Changes imaginable may benbsp;wrought in the human Body, by the Admixture of different Liquors with the Bloodnbsp;even in the fmallefl: Quantities I

* Vid. Rkdi de Gener. InfeSl. p. 127. f Mr. Leeuwenhoek difcovered an Opening on eachnbsp;Side of the Sting for the Emiflion of this Poifon ; which henbsp;fuppofes is not difcharged till the Sting is buried in thenbsp;Wound. Vid. Arc. Nat. Tom. II. p. 167.

CHAP.

The Mifchief done by the Viper, or any other Serpent, is not efFedted by Meansnbsp;of a Sting (for what is darted out of itsnbsp;Mouth, and by the Vulgar fuppofed a Sting,nbsp;is nothing but the Tongue of the Animal,nbsp;and perfedtly harmlefs); but its 'Veeth arenbsp;the dreadful Weapons wherein the Poifonnbsp;lies �, and its Bite is all we need to fear.

Dr. Mead, in his mod: valuable EiTay on the Poifon of the Viper, has defcribed thefenbsp;Teeth and their Poifon fo much betternbsp;than it is poffible for me to do, that I fliallnbsp;beg Leave to borrow the chief I have to faynbsp;from him.

The poifonous Fangs or great �Veeth are crooked and bent : they are hollow fromnbsp;the Root a conliderable Way up, not to thenbsp;very Point (which is folid and fharp to penetrate the better), but to within a little Dif-tanceofit; asmaybefeen byfplitting aToothnbsp;through the Middle. This Cavity ends in anbsp;vifible Slit refembling a Nip or Cut of a Pen.nbsp;See Plate XIII. Fig. XL The Poifon isnbsp;ejedled through this Slit from a Bag at thenbsp;Root of the Teeth, into which it is difchargednbsp;by a Dudl jud behind the Orbit of the Eye,

The venomous Juice of the Viper may be got by enraging it till it bites on fomethingnbsp;folid. This Juice the Dodlor put carefullynbsp;on a Glafs Plate, and examined it by thenbsp;Microjcope. Upon the fifft Sight, he couldnbsp;difcover nothing but a Parcel of fmall Saltsnbsp;nimbly floating in the Liquor: but in a verynbsp;fhort Time the Appearance u^as changed,nbsp;and thofe faline Particles were now fliot outnbsp;as it were into Cryflals of an incrediblenbsp;Tenuity or Sharpnefs, with fomething likenbsp;Knots, here and there, from which theynbsp;feemed to proceed : fo that the whole Texture did in a Manner reprefent a Spider�snbsp;Web, though infinitely finer and more minute 3 and yet withal fo rigid were thefe pellucid Spicula or Darts, that they i^emainednbsp;unaltered upon his Glafs for fev�ral Months.nbsp;And, by confidering the neceflary Ei�e�s ofnbsp;fuch Spicula in the Blood, this learned Phy-fician accounts very reafonably for all thenbsp;Symptoms ufually fucceeding the Bite ofnbsp;this Animal.

Galen fays, xht Momit clanks of his Time ufed, with fome Kind of Paftcj to Hop thenbsp;Perforations in the Teeth o�Vipers, wherebynbsp;they kept in the Venom and then wouldnbsp;fuffer themfelves to be bit, pretending theirnbsp;Antidotes prevented any ill Effeds.

CHAP. xxxn.

Of the Snail.

The * (S/z�/'/has four Eyes, at the Enlt;i of optic Nerves, fheathed in her Horne,nbsp;which fhe can draw in or thruft out, turnnbsp;or diredt, as �he finds moft convenient.

When the Horns are out, cut off nimbly the Extremity of one of them, and placingnbsp;it before the Microfcope, you may difcovernbsp;the black Spot at the End to be really anbsp;Semiglobular Eye.

The Diffedion of this Animal is very curious; for the Microfcope does not only fhevv the Heart beating juft againft a round Holenbsp;near the Neck, which feems the Place ofnbsp;Refpiration ; but alfo the Liver, Spleen,nbsp;Stomach, Veins, Arteries, Guts, Mouth, andnbsp;Teeth. The Guts are green, from the Creature�s eating Herbs, and branched all overnbsp;with fine capillary white Veins. The Mouth,nbsp;is like a Hare�s or Rabbet�s, with four or fixnbsp;Needle-Eeeth refembling thofe of Leeches,nbsp;and of a Subftance like Horn.

Snails are all Hermaphrodites, having both Sexes united in each Individual. Theynbsp;lay their Eggs with great Care in the Earth ;

and

and the young-ones come out, when hatched, with Shells completely formed, and of a Minutenefs proportionable to their own Size.nbsp;Thefe little Shells enlarge, as the Snai/s advance in Growth, by the Addition of newnbsp;Circles, of which Circles they always continue to be the Center.

Cutting off a Snail�s Head, a little Stone appears, * which from its diuretic Qualitynbsp;is of fingular Service in gravelly Diforders.nbsp;Immediately under this Stone the beatingnbsp;Heart is feen, with its Auricles, which arenbsp;membranous ; all of a white Colour, as arenbsp;alfo theVeflels iffuing therefrom. This lit-�nbsp;tie Stone feems intended to ferve inftead of anbsp;Breaft-Bone, which mod: other Creaturesnbsp;have.

It is very remarkable, that Snails difcharge their Excrements at an Opening in thenbsp;Neck, that they breathe there, and that bothnbsp;their Male and Female Parts of Generationnbsp;are fituated near the fame Place. The Malenbsp;Part is very long, and in Shape refembles thenbsp;Penis of a Whale.

HAP.

The common Fly is adorned with Beauties not to be conceived without a Mi-' crofcope. It is ftudded from Head to Tailnbsp;with Silver and Black, and its Body is allnbsp;over befet with Bridles pointing towards thenbsp;Tail. The Head of it contains two largenbsp;Eyes, encircled with Borders of Silver Hairs jnbsp;a wide Mouth, with an hairy Trunk or In-ftrument to take in its Food : a Pair of fhortnbsp;Horns, feveral ftiff black Bridles, and manynbsp;other Particulars difcoverable by the Micro-/cope¹. Its Trunk confids of two Parts, folding over one another, and Iheathed in thenbsp;Mouth. The Extremity thereof is fharpnbsp;like a Knife, for the Separation of any thing.nbsp;The two Parts can alfo be formed occafion-ally into a Pair of Lips for taking up proper Quantities of Food and by the Fly�snbsp;fucking in the Air, they become a Kind ofnbsp;Pump, to draw up the Juices of Fruits ornbsp;other Liquors.

Some Flies are much lighter coloured and more tranfparent than others, and in fuch,nbsp;the Motion of the Guts may be feen very

diftinilly, working from the Stomach towards the Anus; and alfo the Motion of the Lungs, contracting and dilating them-felves alternately. Upon opening a 'Fly, num-berlefs Veins may likewife be difcovered,nbsp;difperfed over the Surface of its Inteftines:nbsp;for the Veins being blackifh, and the Inteftines white, they are plainly vifible by thenbsp;Microfcope, though two hundred thoufandnbsp;Times flenderer than the Hair of a Man�snbsp;Beard. According to * Mr. Leeuwenhoek,nbsp;the Diameter of four hundred and fifty fuchnbsp;minute Veins were about equal to the Diameter of a fingle Hair of his Beard ; andnbsp;confequently two hundred thoufand of themnbsp;puL together would be about the Bignefs ofnbsp;fuch an Hair.

In moft Kind of Flics the Female is furniflred with a moveable Tube at the Endnbsp;of her Tail, by extending of which firenbsp;can convey her Eggs into convenient Holesnbsp;and Receptacles, either in Flefh or fuchnbsp;other Matters as may afibrd the young-onesnbsp;proper Nourifhment. From the Eggs comenbsp;forth minute Worms or Maggots, whichnbsp;after feeding for a while in a voracious Manner, arriving at their full Growth, becomenbsp;transformed into little browm Aurelias y

It would be endlefs to enumerate the different Sorts of Flies which may continually he met with in the Meadows, Woods, andnbsp;Gardens j and impoffible to defcribe theirnbsp;various Plumes and Decorations, furpaflingnbsp;all the Magnificence and Luxury of Drefsnbsp;in the Courts of the greatefl; Princes. Everynbsp;curious Obferver w*ill find them out himfelf,nbsp;and, with Amazement and Adoration, liftnbsp;up his Eyes from the Creature to thenbsp;Creator.

TH E Weevil and the Wolf are two Kinds of fmall Infedfs that do Abundance of Mifchief to many Sorts of Grain,nbsp;by eating into them and devouring all theirnbsp;Subftance.

The Weevil is fomewhat bigger than a large Loufe of the Scarab Kind, with twonbsp;pretty jointed tufted Horns, and a Trunknbsp;or Piercer projecting from the Fore-part ofnbsp;its Head. At the End of the Trunk (whichnbsp;is very long in Proportion to its Body), are anbsp;Sort of Forceps or fharp Teeth, wherewith,nbsp;it gnaws its Way into the Heart of the

By keeping thefe Creatures in Glafs Tubes, with forne few Grains of Wheat,nbsp;their Copulation has been difcovered, andnbsp;likewife their Manner of Generation, whichnbsp;is thus.� The Female perforates a Grainnbsp;of Wheat, and therein depofits a Angle oblong Egg, or two Eggs at moil (a Grain ofnbsp;Wheat being unable to maintain above onenbsp;or two of the young Brood when hatched),nbsp;and this fhe does to five or fix Grains everynbsp;Day for feveral Days together. Thefe Eggs,nbsp;not above the Size of a Grain of Sand, innbsp;about feven Days produce an odd Sort ofnbsp;white Maggots, which wriggles its Bodynbsp;pretty much, but is fcarce able to move fromnbsp;Place to Place, as indeed it has no Occafion,nbsp;being happily lodged by its Parent where itnbsp;has Food enough. This Maggot turns intonbsp;an Aurelia, which in about fourteen Daysnbsp;comes out a peifeB Weevil.

As many People are unacquainted with the Weevil, aPi�iiire of it is given Plate XIII.nbsp;Fig. XII.

Wevils when in the Egg, or not come to their perfect State, are often devoured bynbsp;Mites.

CHAP-

TH E Wolf is a little white Worm or Maggot that infefts Granaries andnbsp;Corn-chambers, and unlefs proper Care benbsp;taken will do unfpeakable Damage.�I callnbsp;it a Worm or Maggot, becaufe under thatnbsp;Form it does the Mifchief, though in itsnbsp;perfect State it is really a fmall Moth, whofenbsp;Wings are white, fpotted with black Spots. 'nbsp;This little Maggot has fix Legs; and, asnbsp;it creeps along, there iffues from its Mouthnbsp;an exceeding fine Thread or Web, by whichnbsp;it faftens itfelf to every Thing it touches, fonbsp;that it cannot fall. Its Mouth is armed withnbsp;a Pair of reddifli Forceps, or biting Inflru-ments, wherewith it gnaws its Way, not onlynbsp;into Wheat and other Grain, but perforatesnbsp;even wooden Beams, Boxes, Books, and al-moft any thing it meets with.

Towards the End of Summer, this pernicious Vermin (in Corn-chambers infefted with them) may be feen crawling up thenbsp;Walls in great Numbers, in Search of proper Places where they may abide in Safetynbsp;during their Continuance in their Aurelianbsp;State : for when the Time of undergoing anbsp;Change into that State approaches, they for-

fake their. Food, and the little Cells they had formed of hollowed Grains of Corn, clottednbsp;together by Means of the Web coming fromnbsp;their Mouths, and wander about till theynbsp;find fome Wooden Beam, or other Body tonbsp;their Mind, into which they gnaw Holesnbsp;with their fharp Fangs, capable of concealing them : and there enveloping themfelvesnbsp;in a Covering of their own Spinning, foonnbsp;become metamorphofed into dark-colourednbsp;Aurelias

Thefe Aurelias continue all the Winter unalt;ftive and harmlefs : but about April ornbsp;May, as the Weather grows warm, theynbsp;are transformed anew, and come forthnbsp;Jp/Ioths of the Kind above defcribed. Theynbsp;may then be feen in great Numbers takingnbsp;little Flights, or creeping along the Wails inbsp;and, as they eat nothing in their Fly-ftate,nbsp;are at that Time not mifchievous. But theynbsp;foon copulate and lay Eggs (fliaped like Hen�snbsp;Fggs, blit not larger than a Grain of Sand),nbsp;each Female fixty or feventy, v/hich, bynbsp;Means of a Tube at the End of her Tail, fhenbsp;thrufls or infinuates into the little Wrinkles,nbsp;Hollows, or Crevices, of the Corn where,nbsp;in about fixteen Days, they hatch, and thennbsp;the Plague begins : for the minute Wormsnbsp;cr Maggots immediately perforate the Grain

they were hatched upon, eat out the very Heart of it, and with their If'ehs cementnbsp;other Grains thereto, which they likewifenbsp;fcoop out and devour, leaving nothing butnbsp;Hulks and Dull, and fuch a Quantity ofnbsp;their Dung as fnews them to be more voracious Infetls than the Weevil.

The watchful Obferver has two Opportunities of deftroying this Vermin, if they happen to be got among his Corn. One is, when theyforfake theirFood and afeend the Walls,nbsp;which they will fometimes almoft cover ;nbsp;the other, when they appear in the Mothnbsp;State. At both thefe Times they may benbsp;crufhed to Death againft the Walls in greatnbsp;Numbers by clapping Sacks upon them.nbsp;But they may ftill be exterminated morenbsp;elfedually, if, clofing up all the Doors andnbsp;Windows, the Corn-chamber be filled withnbsp;the Fumes of Brim/lone, by leaving it burningnbsp;on a Pan of Charcoal, without giving it anynbsp;Vent for twenty-four Hours. Great Cautionnbsp;however muft be ufed, to open the Windows and Doors, and let all the Fumes benbsp;entirely gone before any body enters thenbsp;Place afterwards, for Fear of Suffocation;nbsp;The Fumes of Sulphur are in no wife hurtful to the Corn, or give it any Tafle.

The Picture of the Wolf in its Reptile State (when it goes by that Name) is fhewnnbsp;Plate XIII. Fig. XIII. �.

Old Corn is lefs fubjed: to thefe devouring Infeds than Corn that is new; for its Skinnbsp;being more hard and dry it is much morenbsp;difficult for the little Maggots when fitftnbsp;hatched to penetrate ¹.

TH E F.yes of InfeBs are amazing Pieces of Mechanifm, whofe Strudure andnbsp;Difpofftion, without the Afliftance of thenbsp;Microfcope, would for ever have been unknown to ns.�Beetles, Dragon-fies, Bees,nbsp;W.afps, Ants, common Flies, Butterflies, andnbsp;many other InfeSls, have two Crefcents, ornbsp;immoveable Caps, compohng the greateftnbsp;Part of the Plead, and containing a prodigious Number of little Hemifpheres or roundnbsp;Protuberances, placed with the utmoft Regularity and Exadnefs in Lines crofling eachnbsp;Other, and refembling Lattice-work. Thefe

I call this Infeftche Wolf from the Latin Name Lupus ; given, I fuppofe, for its VoracLoufnefs.

f SpecfacU de la Nature, Dial. VIII. Hoon's Micreg. p. io8. Leeuw. Arc.Nat^'Tom. III. Part. II.p. 4.1. Again,nbsp;p. 424. Derham�s Phyf. TheoL 364.

are a Colledtion of fo perfedlly fmooth and poii�hed, that like fo many Mirrors theynbsp;refle�t the Images of all outward Objects.nbsp;One may fee the Figure of a Candle multiplied almoft to Infinity on their Surfaces,nbsp;fhifting its Beam into each Eye, accordingnbsp;to the Motion given it by the Obferver�snbsp;Hands : and as other Creatures are obligednbsp;to turn their Eyes to Objefts, this Sort havenbsp;fome or other of their Eyes always readynbsp;diredled towards Objedts on whatever Sidenbsp;they prefent themfelves. In ihort, all ihefenbsp;little Hemifpheres are real Eyes, having in thenbsp;Middle of each a. minute tranfparent Lensnbsp;and Pupil, through which Objects appearnbsp;topfy-turvy as through a convex Glafs :nbsp;This becomes alfo a fmall Lelefcope whennbsp;there is a jufl focal Diftance between it andnbsp;the Lens of the Microfcope. It is alfo rea-fonable to believe, that every Lens has a dif-tindt Branch of the Optic Nerves adminif-tring to it: and yet, that Objedls are notnbsp;multiplied, or appear other wife than fingle,nbsp;any more than they do to us, who fee not annbsp;Objedt double though we have two Eyes.

Every Man almofi: that has feen a Microfcope has been entertained with a View of thefe minute Eyes, and yet very few perhapsnbsp;have well confidered either the Nature ornbsp;the Number of them. Mr. Hook computed fourteen thoufand Hemifpberes in the

two Eyes of a JOrone, viz. feven thoufand in each Eye. Mr. Leeuwenhoek reckonednbsp;�X thoufand t\vo hundred thirty-�x in anbsp;Silk-Worm^ two Eyes when in its- Fly-State jnbsp;th ree thoufand one hundred ei�chty-one innbsp;each Eye of a beetle j and eight thoufandnbsp;in the two Eyes of a common Fly. 1�henbsp;Lihella, Adder-Bolt^ or Dragon-Fly, is thenbsp;mofl remarkable of all the Infedfs we knownbsp;for its large and fine pearled Eyes j Xvhich,nbsp;even with a common Readihg-glafs, appearnbsp;like the Skin we call Shagreen. Mr. Leeuwenhoek reckons in each Eye of thisnbsp;Creature twelve thoufand five hundred forty-four Lenfes, or, in both, twenty-five thoufand eighty-eight j placed in an bexangularnbsp;Pofiticn, each Lens having fix others roundnbsp;it; which is alfo the Order moft commonnbsp;in other Eyes. He likewife obferved in thenbsp;Center of each Lens a minute tranfparentnbsp;Spot, brighter than the reft, and fuppofed tonbsp;be the Pupil through which the Rays ofnbsp;Light are tranfmitted upon the Rethta. Thisnbsp;Spot had three Circles furrounding it, andnbsp;feemed feven Times lefs than the Diameternbsp;of the whole Lens. We fee here, in each ofnbsp;thefe exceedingly minute lenticular Surfaces,nbsp;as much Accuracy in the Figure and Polifh,nbsp;and as much Contrivance and Beauty, as innbsp;the Eye of a Whale or an Elephant: andnbsp;hxow delicate, how exquifitely delicate, muftnbsp;the Filaments of the Retina be which ferve

to each of thefe, fince the whole Pi�lure of Obje�ls painted thereon muft be Millions ofnbsp;Times iefs than the Images of them pictured on the human Eye!

If we cut off the 'Eye o� z Dragon-Fly, of a Drone, or a common Fly, and with a Pencilnbsp;and fome clean Water wafh out all the Vef-fels, thofe Veffels may be examined by thenbsp;Microfeope, and the Numbers of them willnbsp;appear wonderful and furprizing ; and thennbsp;if the outward Covering be dried carefully,nbsp;fo as not to Ihrink, it will be rightly prepared for making Experiments with thenbsp;Microfeope: and, upon viewing it, we fhallnbsp;perfectly diftinguiih the numerous Protuberances or Demifpheres, divided from onenbsp;another, with a fmall Light iffuing between,nbsp;them, and.fix Sides to each. Mr. Leeuwenhoek, having prepared an Eye in thisnbsp;Manner, placed it a little farther from hisnbsp;Microfeope than when he would examine annbsp;Objedl: fo as to leave a right and exadt/i-cal Diflance between it and the Lens of his �nbsp;Microfeope; and then looking through both,nbsp;in the Manner of a Lelefcope, at the Steeplenbsp;of a Church, which was two hundred ninetynbsp;and nine Feet high, and feven hundred andnbsp;fifty Feet from the Place where he flood, henbsp;could plainly fee, through every little Lens,nbsp;the whole Steeple, inverted, tho� not largernbsp;than the Point of a fine Needle ; and then

dire�ling his View to a neighbouring Houfe, he f'aw, through Abundance of the littlenbsp;mifpheres, not only the Front of the Houfe,nbsp;but likewife the Doors and Windows ; andnbsp;was able to difcern didiin�tly whether thenbsp;Windows w'ere Ihut or open.

There can be no Doubt, that Lice, Mites, and Multitudes of other Animalcules muchnbsp;fmaller ftill than they, have Eyes contrivednbsp;and fa/liioned to difcern Obje�ls fome thou-fands of Times lefs than themfelves: for fonbsp;the minute Particles they feed on, and manynbsp;other Things neceffary for them to diftin-guifh and know perfectly, muft certainlynbsp;be.�What a Power then of magnifying arenbsp;fuch Eyes endued with ! and what extraordinary Difcoveries might be made, were itnbsp;poffible to obtain Glaffes through which wenbsp;could fee as they do !

rquot;|^HE Horns of InfeBs have been thought I by many defigned only to clean theirnbsp;Eyes, by wiping off any Duff that may fallnbsp;thereon : but as we conftantly obferve them

performing that Office with their Fore-legs, it is certain their Horns muH; be intended fornbsp;fome other Purpofe. And fince they arenbsp;perpetually feeling before them with theirnbsp;Antennce�iL% they walk along, *Mr. Derhamnbsp;very reafonably imagines them abfolutelynbsp;neceffary to fearch and find out their Way.nbsp;For as their Eyes are immoveable, fo thatnbsp;no Time is required for their turning themnbsp;to Objedis, there is no Neceffity that thenbsp;Retina, or Optic Nerve, fhould occafionallynbsp;be brought nearer to, or removed farthernbsp;from the Cornea, as it is in other Animals ;nbsp;which would require Time: but their Corneanbsp;and Optic Nerve being always at one andnbsp;t'he fame Diftance, and fitted only to feenbsp;diftant Objcds ; they would be infenfiblenbsp;of, and apt to run their Heads againft Bodiesnbsp;very near them, were they not affifted bynbsp;their Feelers.

And that this, rather than wiping the Eyes, is the chief Ufe of the Feelers, is farther manifeft from the Antenna of the Flejh~nbsp;Fly, and many other Infeds, which arenbsp;flaort and ftrait, and uncapable of being bentnbsp;down to, or extended over the Eyes: as alfonbsp;from others enormpufly long, fuch as thofenbsp;of the Capricorni or Goat Chafers, thenbsp;Cadew Fly, and divers others both Beetlesnbsp;and Flies.

The lamellated Antennee of fome, the clavellated of others, the Topknots orTuftanbsp;like Dandelion Seeds, the branched, the feathered, and divers other Forms of Horns ofnbsp;the Beetle, Butterfly, Moth, Gnat, and manynbsp;Kinds befide, are furprizingly beautifulnbsp;when viewed thro� a Microfeope. And innbsp;fome thefe Antennce diftinguifh the Sexes :nbsp;for in the Gnat-kind all thofe with Tufts,^nbsp;Feathers, or Brufh-horns (of which therenbsp;are great Varieties), are Males: thofe withnbsp;fhort fingle-fliafted Horns are Females^

TPIERE is fuch infinite Variety in the Contexture, Formation, Difpofition,nbsp;and Ornaments of the Wings of InJeBs, according to their different Wants and Ways ofnbsp;Life, that nothing but a curious Obfervationnbsp;can make us have any true Conception of it.nbsp;Some Wings are filmy, as thofe of Dragon-Flies-, others are fluck over with fliort Brif-tles, as in Fleflo-fies: fome are Films covered with fhort Feathers, like the Tiles of anbsp;Houfe, as in Butterfiies and Moths -, othersnbsp;have divided Wings, as the grey and whitenbsp;6nbsp;nbsp;nbsp;nbsp;feathered

feathered Moth. The Wings of many Sorts of Gnats are adorned with Rows of Feathersnbsp;along their Ridges, and Borders of Feathersnbsp;round their Edge. Some again have Hairs,nbsp;and others Hooks, placed v/ith the greateft:nbsp;Regularity and Order. All of the Scarabnbsp;Kind have Elytra, or Cafes, into which theirnbsp;Wings are folded and preferved until theynbsp;want to employ them. Some of thefe Cafesnbsp;reach almoft to the Extremity of the Tail,nbsp;as in moft Kinds of Beetles �, and others arenbsp;very fhort, as in the Ear-Wig. Many ofnbsp;them are likewife extremely beautiful whennbsp;brought before the Microfcope^

All thefe Kinds of Wings have certain bony Parts or Ribs, that give them Strength,nbsp;along the Sides of which run large Blood-Veffels, branching out into numberlefs Di-vifions, and conveying Nourifliment to thenbsp;intermediate Parts : for tho� no Circulationnbsp;can be difcerned in them, it being probablynbsp;extremely flow, we can fcarce doubt thatnbsp;there mufl; be continually a Supply of Juicesnbsp;to the Quills, Hairs, or Briflles,, wherewithnbsp;they are armed or ornamented.

As to,Motion, Wings that are filmy move fafter than thofe covered with Feathers. Mr.nbsp;Hook obferves, that in the Wings of fomenbsp;minute Flies there are many hundreds, ifnbsp;not thoufands of Vibrations in a Second,nbsp;and fuppofes them the fwiftefl. Vibrations in

the World : whence he refle�ts very ingeni-oufly, on the Quicknefs of the Animal Spirits, that ferve to fupply this Motion.

Thofe converfant in Microfcopes need not be informed, that the beautiful Colours onnbsp;the Wings of Butterflies and Moths are owing to elegant minute Feathers ending innbsp;Quills, and placed with great Exa�lnefs innbsp;orderly Rows j as, when rubbed off, thenbsp;Holes they come from fliew : but few, itnbsp;may be, have much obferved the great Variety of their Make, not only in Moths andnbsp;Butterflies of different Sorts, but even innbsp;thofe taken from different Parts of the famenbsp;Wing j infomuch that it is pretty difficultnbsp;to find any two of them exadlly alike.

Rub thefe Feathers gently off, with the End of your Finger or Pen-knife 3 and,nbsp;breathing upon a Angle 'Talc in one of yournbsp;Sliders, apply it to the Feathers, which feernnbsp;only like a fine Duft, and they will immediately adhere to it; then placing it beforenbsp;the Microfcope, if they are not perfect, ornbsp;lie not to your Mind, wipe them off, and putnbsp;on others in the fame Manner, till you getnbsp;thofe you like : then cover them with another Talc, and faften it dowm with a Wire,nbsp;that you may preferve them for future Examination. Look at them with the third ornbsp;fourth, then with the fecond, and at lafl; withnbsp;the greatef Magnifier.

The Wing �f a Midge is a moPc curious Objed:, and fo indeed is every Part of thatnbsp;minute Infe�l. The Wing of the little Plumenbsp;Moth is compofed of feveral diftind Quills,nbsp;like thofe of Birds. There are alfo Wingsnbsp;folded up in the little Cafes on the Backs ofnbsp;Earwigs, very pretty to examine. But nonbsp;more need be faid of Wings, lince everynbsp;body muft be fenlible the great Variety ofnbsp;them is an endlefs Subjed of Enquiry andnbsp;Admiration.

Most Infeds having but two Wings, are provided with a little Ball ornbsp;Bladder under each, fet at the Top of a (lender Foot-ftalk, which is moveable every Waynbsp;at Pleafure. With thefe they balance them-felves in Flight as a Rope-Dancer does withnbsp;his Pole leaded at each End �, and if one ofnbsp;them be cut off, the Creature flies for a whilenbsp;very awkwardly, as if over-heavy on one Side,nbsp;and falls at lad to the Ground. Thefe Bladders being hollow may ferve likewife to produce the Noife many Sorts of Flies make, bynbsp;(Iriking their Wings againfl them, and be anbsp;Means of finding out one another. In fomenbsp;VoL. I.nbsp;nbsp;nbsp;nbsp;Rnbsp;nbsp;nbsp;nbsp;Creatures

Creatures they hand alone, but the wholes FlyTribe have little Covers or Shields undernbsp;which they lie and move. Infefts that havernbsp;four Wings balance themfelves with thenbsp;two lei��r ones, and as they want not, havenbsp;none of thefe little Poifes. The Microfcoptnbsp;may probably find out fiill farther Beauties,nbsp;Contrivances, and Ufes for them than havenbsp;been yet difcovered.

^ H 1H E Scales or outfde Coverings of Fijhes are formed with furprizing Beautynbsp;and Regularity; and, in different Kinds ol:nbsp;them, exhibit an endlefs Variety in Figurenbsp;and Contexture. Some are longifli, fomenbsp;round, fome triangular, fome fquare, andnbsp;fome or other of all Shapes we can well imagine. Some again are armed with fharpnbsp;Prickles, as thofe of the Pear-ch, Soal, amp;c.nbsp;Others have fmooth Edges, as of the Cod-fjh. Carp, Pench, See. There is likewife anbsp;great Variety even in the fame Filh; for thenbsp;Scales taken fro-m the Belly, the Back, thenbsp;Sides, the Head, and all the other Parts, arenbsp;very different from one another. And, indeed, for Variety, Beauty, Regularity, and

tlie Order of their Arrangement, the Scales of Fifhes bear a near Refemblance to thenbsp;Feathers on the Bodies and Wings of Mothsnbsp;and Butterflies.

Thefe Scales are not fuppofed to be fhed every Year nor during the whole Life ofnbsp;the Fifli; but to have an annual Additionnbsp;of a new Scale, growing over and extendingnbsp;every Way beyond the Edges of the former,nbsp;in proportion to the Fifh�s Growth j fome-what in the fame Manner as the Wood ofnbsp;Trees enlarges yearly by the Addition of anbsp;new Circle next the Bark. And as the Agenbsp;of a Tree may be known by the Number ofnbsp;Ringlets its Trank is made up of, fo in Fifhesnbsp;the Number of Plates compofing their Scalesnbsp;denote to us their Age. It is alfo probable,nbsp;that as there is a Time of Year when Treesnbsp;ceafe to grow, or have any farther Additionnbsp;to their Bulk, the fame Thing happens tonbsp;the Scales in Fifhes; and that afterwards,nbsp;at another Time of Year, a new Addition,nbsp;Increafe, or Growth, begins. Somewhat likenbsp;this in Birds and Beafts their Feathers andnbsp;Hairs demonftrate.

Mr. Leeuwenhoek took fome Scales from an extraordinary large Carp, forty-twonbsp;Inches and a half long, and thirty-three andnbsp;a quarter in the Round, Rynland Meafure,

R 2 nbsp;nbsp;nbsp;which

which were as broad as a Dollar. Thefe he macerated in warm Water to make themnbsp;cut the eafier : and then cutting obliquelynbsp;through one of them, beginning with thenbsp;firft-formed and very little Scale in the Center, he, by his Mlcrofcape, plainly diftin-guifhed forty Lamella or Scales, glewed as itnbsp;were over one another; whence-he concluded, that the.Fi�hwas forty Years of Age¹'.

It has generally been imagined, that an Lei has got no Scales; but if its Slime benbsp;wiped clean away, and the Skin be examinednbsp;by a Microfeope, it will be found coverednbsp;with exceeding fmall Scales, ranged in anbsp;very orderly and pretty Manner j and I believe few Fithes, unlefs fuch as have Shells,nbsp;are to be found without Scales.

The Way of preparing Scales is to take them off carefully with a Pair of Nippers,nbsp;wafh them very clean, and place them in anbsp;fmooth Paper, between the Leaves of anbsp;Book, to make them dry flat, and preventnbsp;their fhrivelling up. Then place them between your Talcs in Sliders, and keep themnbsp;for Examination.

The Snake, the Viper, the Slow-worm, the Lizard, the Eft, amp;c. afford a farthernbsp;Variety of Scales.

C 239 y

CHAP. XLI.

IN the clear Liquor of an Oyfter many little round living Animalcules have beennbsp;found, whofeBodies being conjoined,formednbsp;fpherical Figures, with Tails, not changingnbsp;their Place but by linking tovvards the Bottom, as being heavier than the Fluid : thefenbsp;were feen fometimes feparating, and prefent-ly afterwards coming together and joiningnbsp;themfelves again. In other Oyfters Animalcules of the fame Kind were found, not conjoined, but fwimming by one another, whencenbsp;they feemed in a more perfed: State, andnbsp;were fuppofed by Mr. Leeuwenhoek tonbsp;be the Animalcules in the Ro w or Semen ofnbsp;the Oyfter ¹.

A Female Oyfter being opened, incredible Multitudes oimmnlcEmbryo~Oy/iers coverednbsp;with little Shells perfedly tranfparent werenbsp;plainly feen therein, fwimming along flow-ly; in another they were found of a brownilhnbsp;Colour without any apparent Life or Motion. Monfieur Joblot kept the Waternbsp;running from Oyfters three Days, and it appeared full of young Oyfters that fwam about

nimbly, and increafed in Bignels daily. A Mixture of Wine, or the very Vapour ofnbsp;Vinegar, killed them.

In the Month of Augujl Oyfters are fup-pofed to breed, becaufe young-ones are then found in them. Mr, Leeu\venhoeknbsp;opened an Oyfler on the fourth of Augujl,nbsp;and took out of it a prodigious Number ofnbsp;minute Oyfters all alive, and fwimmingnbsp;hrilkly in the Liquor, by the Means of certain exceedingfmall Organs extending alittlenbsp;Way beyond their Shells, which he calls theirnbsp;Beards. In thefe little Oyfters he could dif-tinguifti the joining of the Shells: and perceive fome that were dead, with their Shellsnbsp;gaping, and as like large Oyfters in Form asnbsp;one Egg is like another.

As for the Size of thefe Embryo-Oyfters, he computes, that one hundred and twentynbsp;of them in a Row would extend an Inch jnbsp;and, confequently, that a globular Body,nbsp;whofe Diameter is an Inch, would, if theynbsp;were alfo round, be equal to one Millionnbsp;feven hundred and twenty-eight thoufand ofnbsp;them. ¹ He reckons three or four thou-land are in one Oyfter, and found many ofnbsp;the Embryo-Oyfters among the Beards, fomenbsp;faftened thereto by flender Filaments, and

others lying loofe. He likewife found other Animalcules in the Liquor five hundrednbsp;Times fmaller than Embryo-Oyiders.

IT is not very uncommon to fee on the Shells of Oyfters, when in the Dark, anbsp;fhining Matter, or blewifo Light, like thenbsp;Flame of Brimftone, which flicks to thenbsp;Fingers when touched, and continues fliiningnbsp;or giving Light a confiderable Time, tho�nbsp;without any fenfible Heat¹'. Monf. Aux autnbsp;obferved this fnning Matter with a Micro-fcope, and difcovered it to confifl of threenbsp;Sorts of Animalcules. The firfl whitifh,nbsp;having twenty-four or twenty-five Legs onnbsp;each Side, forked ; a black Speck on onenbsp;Part of the Head; the Back like an Leinbsp;with the Skin ftripped oif. The fecond Sortnbsp;red, refembling the common Glow-worm,nbsp;with Folds on its Back, but Legs like thenbsp;former, a Nofe like a Dog�s, and one Eyenbsp;in the Head. The third Sort fpeckled, anbsp;Head like a Seal, with many Tufts of whitiflinbsp;Hairs on the Sides thereof. He faw alfonbsp;fome much larger and greyilh, having a

great Head, two Horns like a Snail�s, and lix or eight whitifli Feet: but thefe fhinednbsp;not.

As the Bodies of Lobders and fome other Kinds of Fiihes, tainted Flefli, rottennbsp;Wood, and other Subftances, are fometimesnbsp;found to Ihine with a Light refembling thenbsp;foregoing, may it not probably proceed fromnbsp;the fame Caufe, namely, from Animalcules ?nbsp;Some have alfo fuppofed, that the Ignis Fa-tuus, Will-in-a-Wifp, or fack-a-Lanthorn,nbsp;is nothing elfe but a Swarm of minute flyingnbsp;Infedts, that emit Light around them in thenbsp;Manner Glow-worms do : and, indeed, thenbsp;Motions and feveral other Circumftances ofnbsp;this Sort of Fire (if I may fo term it) feemnbsp;favourable to fuch Opinion.

The Curious will judge it proper to examine this Matter carefully, and to them it is fubmitted.

delightful Objedl for the Microfcopeand that, in the tranfparent Membrane whichnbsp;immediately appears on opening of the Shell,

the Blood may be feen circulating through an amazing Number of Veffels, even in thenbsp;fmalleft Particle of it that can be applied fornbsp;Examination.

Mr. Leeuwenhoek, in feveral that he differed, difcovered Numbers of Eggs, ornbsp;Embryo-Mufcles, in the Ovarium, appearingnbsp;as plainly as if he had feen them with thenbsp;naked Eye, lying with their fharp Endsnbsp;faftened to the Strings or Veffels wherebynbsp;they receive Nourifhment. Thefe minutenbsp;Eggs, or Embryo-Mufcles, are, in due Time,nbsp;laid or placed by the Parent, in a very regular and clofe Order on the Outfide of thenbsp;Shell: where, by Means of a glewy Matter,nbsp;they adhere very faft, and continually in-creafe in Size and Strength, till, becomingnbsp;perfed: Mufcles, they fall off and fliift fornbsp;themfelves, leaving the Holes where theynbsp;\4fere placed behind them. This Abundancenbsp;of Mufcle-Shells viewed by the Microfcopenbsp;can fhew. Sometimes two or three thoufandnbsp;of thefe Eggs adhere to the Shell of onenbsp;Mufcle ; but it is not certain they were allnbsp;fixed there by the Mufcle itfelf, for theynbsp;frequently place their Eggs on one another�snbsp;Shells. The fringed Edge of the Mufcle,nbsp;which Mr. Leeuwenhoek calls the Beard,nbsp;has in every the minuteft Part of it fuch anbsp;Variety of Motions as is inconceivable : fornbsp;being compofed of longilh Fibres, each Fibrenbsp;has on both Sides a vaft many moving Parti-t 2nbsp;nbsp;nbsp;nbsp;cles.

The Threads or Strings, which we term the Beard, are compofed of a Glew whichnbsp;the Mufcle applies by the Help of its Trunknbsp;to fome fixed Body, and draws out as a Spider does its Web, thereby faftening itfelf,nbsp;that it may not be wafhed away. IfMufclesnbsp;he put into Salt and Water, we may havenbsp;the Pleafure of feeing them perforni thisnbsp;Work, and faften themfelves to the Sides ornbsp;Bottom of the VelTel we place them in.

Cockles, Scallops, Limpets, Periwinkles, and Abundance of other Shell-fifli, are Ob-jedts that have as yet been very llightly examined by the Microfcope j and therefore thenbsp;ferious Enquirer into Nature�s fecret Operations may here be certain of difcoveringnbsp;Beauties which at prefent he can have nonbsp;Conception of.

� Phil. Tran/. Numb, 336. Arc. Nat. Tom. II. p. 19. amp;C. Tom. IV. p. 423, amp;c.

CHAP;

TPI E Hairs of Animals are very different in their Appearance before the Microfcope, and can furnifh out a great V'a-riety of pleafing Obfervations. Malpighinbsp;difcovered them to be tubular, that is, com-pofed of a Number of extremely minutenbsp;Tubes or Pipes, in his Examination of anbsp;Horfe�s Mane and Tail, and in the Bridlesnbsp;of a Boar. Thefe Tubes were mod didin-guifhable near the End of the Hairs, wherenbsp;they appeared more open: and he fometimesnbsp;could reckon above twenty of them. In thenbsp;Hedge-hog�s Prickles, which are of the Nature of Hairs, he perceived thefe Tubes very plainly, together with elegant medullarynbsp;Valves and Cells.

There are alfo in the Hairs of many Animals, in fome tranfverfe, in others fpiral Lines, fomewhat of a darker Colour, running from Bottom to Top in a very prettynbsp;Manner. A ¹ Moufe�s Hairs are of thisnbsp;Sort i they appear as it were in Joints likenbsp;the Back-bone, are not fmooth but jaggednbsp;on the Sides, and terminate in the fharpeftnbsp;Point imaginable. Hairs taken from a

246 nbsp;nbsp;nbsp;Q/quot; H AIRS.

The Hairs of Men, Horfes, Sheep, Hogs, amp;c. are compofed of fmall, long, tubularnbsp;Fibres or fmaller Hairs, encompalTed with anbsp;Rind or Bark; from which Structure a fplitnbsp;Hair appears like a Stick ihivered with beating. They have Roots of different Shapesnbsp;in different Animals, become lengthened bynbsp;Propulfion, and are thicker towards thenbsp;Middle than at either End.

Hairs of Indian Deer are perforated from Side to Side : our Englijh ones feem coverednbsp;with a Kind of fcaly Bark. The Whifkers ofnbsp;a Cat, cut tranfverfely, have fomewhat innbsp;the Middle like the Pith of Elder. * Thenbsp;Quills of Porcupines or Hedge-hogs havenbsp;alfo awhitifh Pith in a Star-like Form : andnbsp;a human Hair cut in the fame Manner fliewsnbsp;a Variety of Veffels in very regular Figures,

Hairs taken from the Head, the Eyebrows, the Noftrils, the Beard, the Hand, and other Parts of the Body, appear unlike,nbsp;as well in the Roots as in the Hairs them-felves, and vary as Plants do of the famenbsp;Genus, but of different Species.

CHAP.

[ 247 1

TH E Farina, or mealy Powder, found on the little pendant Tops of almoftnbsp;every F'lower, is fomewhat fo analogous tonbsp;the Semen of Animals, that it deferves thenbsp;ftridteft and moft attentive Examination.

This Powder, whofe Colour is different in Flowers of different Kinds, was imagined,nbsp;by former Ages, to be a mere excrementi-tious and unneceffary Part of the Plant: butnbsp;the Microfcope here alfo has made furprizingnbsp;Difcoveries, by fhewing, that all the minutenbsp;Grains of this Powder are regular, uniform,nbsp;and beautiful little Bodies, conftantly of thenbsp;fame Figure and Size, in Plants of the famenbsp;Species, but in different Kinds of Plants asnbsp;different as the Plants themfelves.

It was impoffible to obferve this Order and Configuration of the Farince, withoutnbsp;concluding, that Providence, which nevernbsp;afts in vain, muft intend a nobler Ufe fornbsp;Bodies fo regularly formed, than to be diffi-pated by the Winds and lofl. This Refledlionnbsp;drew on farther Exaniination ; and farthernbsp;Examination, by the Help of the fame In-ftrument, foon difcovered, that this Powdernbsp;is produced and preferved with the utmofi:

Care, in Veffels wonderfully contrived to open and difcharge it when it becomes mature : that there is likewife a Pijiil, Seed-Vejfel, or Uterus, in the Center of the Flower,nbsp;ready to receive the minute Grains of thisnbsp;Powder, as they either fall of themfelves, ornbsp;are blown out of their little Cells. Andnbsp;Experience, founded on numberlefs Experiments, proves, that on this depends entirelynbsp;the Fertility of the Seed: for if the Farina-VeJJels be cut away before they open andnbsp;fhed their Powder, the Seed becomes barrennbsp;and unproductive.

This Farina is therefore judged to be the Male Seed of Plants, and every little Grainnbsp;of its Powder may polTibly contain in it anbsp;minute Plant of the Species whereto it belongs.�It is wonderful to obferve the various Contrivances Nature employs to prevent this Powder from being unprofitablynbsp;difperfed, and to affift its Entrance into thenbsp;proper Pijiil, Seed-Vejel, or Uterus, preparednbsp;for it. The Tulip, for Inftance,w�hich ftandsnbsp;upright, has its Pijiil fliorter than the Fari-na-VeJfels, that the Powder may fall direCtlynbsp;on it; but in the Martagon, which turnsnbsp;downwards, the Pijiil is longer than the faidnbsp;VelTels, and fwells out at its Extremity, tonbsp;catch the Farina hanging over it as itnbsp;flieds.

A Mind inquifitive into Nature�s hidden Beauties will find inexprefllble Delight innbsp;examining and confidering the endlefs Variety difcoverable in the Farince of number-lefs vegetable Species. In that of the Mallow, each little Grain appears to be an opakenbsp;Ball with Prickles iffuing from it on everynbsp;Side. The Sun-Flower Farina feems com-pofed of flat circular minute Bodies, fharp-pointed round the Edges ; the Middle ofnbsp;them appears tranfparent, and exhibits fomenbsp;Refemblance of the Flower it proceeds from.nbsp;The Powder of the Tulip is exactly fhaped,nbsp;like the Seeds of the Cucumbers and Melons.nbsp;The Farina of the Poppy appears like Pearl-Barley, with a Furrow, as in that, reachingnbsp;from End to End. That of the Lily is anbsp;great deal like the Tulip.

I will not anticipate the Pleafure of the Curious, or take up their Time in defcrib-ing more of the Farince, which every Flowernbsp;they come at prefents to their Examination 5nbsp;but advife them, not to negledl the VelTelsnbsp;that contain it, for they will find Beauties innbsp;them alfo fufiicient to reward their Pains.

Gather your Farina in the Midfl of a fun-fhiny dry Day, when all the Dew is off:nbsp;be careful not to fqueeze or prefs it, butnbsp;fhake or elfe gently brufh it off with a foftnbsp;Hair Pencil upon a Piece of clean white Palonbsp;nbsp;nbsp;nbsp;per.

per. Then take a fingle Talc or Illnglafs between your Nippers, and, breathing on it,nbsp;apply it inftantly to the Farina, which thenbsp;Moifture of your Breath will make adhere tonbsp;it. If too great a Quantity of Powder feemsnbsp;flicking to your Ifinglafs, gently blow off anbsp;little ; if there be not enough, breathe on itnbsp;again, and touch the Farina with it as before. Then put your Glafs into the Hole ofnbsp;a Slider, and apply it to the Microfcope, tonbsp;fee if the little Grains are fpread according tonbsp;your Liking ; and when you find they are,nbsp;cover them cautioufly with another Talc,nbsp;which faften down with a Brafs-wire ; butnbsp;let not the Glafles prefs hard upon the Farina, for that will deflroy its true Figure,nbsp;and reprefent it different from what it is.

A Colle�lion of the moft remarkable Farina thus preferved muft: be a ladingnbsp;Entertainment to thofe who ftudy Nature : to fuch I alfo recommend a diligentnbsp;Examination of the little Cells that contain the Farina, and likewife of the Pifiilsnbsp;or Uteri, and other Parts of Generation innbsp;Flowers. Let them only begin with thenbsp;Arch-Angel, or blind Nettle with a whitenbsp;Flower, or even with the common Mallow,nbsp;and they will difcover Beauties impoflible tonbsp;be defcribed. And as every other Flowernbsp;has Organs for the fame Purpofe, though ofnbsp;-a different Form and Strutffure, here are

Wonders In Abundance for the Microfcope to difcover, and happy the Man who can findnbsp;moft Leifure to explore thefe Woidds as yetnbsp;unknown !

I fliall add only one Obfervation more before I leave this Head, which is, that asnbsp;the Animalcules in Semine differ not in Big-nefs according to the Size of thofe Animalsnbsp;whence the Semen comes : fo the tninutenbsp;Grains compofing the. Farince of Vegetablesnbsp;are not bigger or lefs in Proportion to thenbsp;Size of the Plants producing them, but arenbsp;often the dire�f contrary ; as we find by thenbsp;Farina of the litt�e creeping Mallow, thenbsp;Globule

Of Seeds.

Each Seed includes a Plant: that Plant, again. Has other Seeds, which other Plants contain :nbsp;Thoie ether Plants have all their Seeds; and Thofanbsp;More Plants, again, fucceffively inclofe.

Of Seeds.

Amazing Thought ! what Mortal can conceive Such vvond�rous Smallnefs!�Yet we muft believenbsp;What Reafon tells ; for Reafon�s piercing Eyenbsp;Difcerns thofe Truths our Senfes can't defcry.

I hope to be excufed for borrowing the Lines above from a little Poem of my own,nbsp;called Phe Univerfe, publifhed fome Yearsnbsp;ago ; as they contain a Suppofition, which,nbsp;however chimerical it may appear at firft,nbsp;will, if duly confidered, be found, perhaps,nbsp;not only poffible, but even highly probable: Malpighi, Leeuwenhoek, Hooke,nbsp;Grev/, and feveral others bear Witnefs, thatnbsp;the Microfcope has difcovered minute Plantsnbsp;not only in the larger Seeds, fuch as thenbsp;Walnut, Chefnut, Acorn, Beechnut, Seed-of the Lime, Cotton-Seeds, Peafe, amp;c. butnbsp;alfo in the finaller of Radiih, Hemp, Chervil, Scurvy-grafs, Muftard, and Multitudesnbsp;of other Seeds. About two Years ago, Inbsp;likewife had the Honour to prefent the Dif-fe�ion of a Seed of the Gramen tremuliwhnbsp;or tremblmg Grafs, with an Account thereof, to the Royal Society, wherein a perfedlnbsp;Plant appeared, with its Root, fending forthnbsp;two Branches, from each of which feveralnbsp;Leaves or Blades of Grafs proceeded. Thusnbsp;far our Sight, aiTilled by the Microfcope,nbsp;is able to difcovcr ; and as that Inftrument

convinces us, that Nature in her Operations is in no wife confined to ourConceptions ofnbsp;Bignefs, but a6ts as freely in the minute Fabric of a Mite, as in the bulky Compafs ofnbsp;a Whale or Elephant �, nay, that fhe rathernbsp;feems to wanton in her Skill, by giving anbsp;greater Number of Limbs, and more numerous Ornaments, to the minute Creaturesnbsp;than to the larger ones. When thefe Things,nbsp;I fay, are feen and refledled on, it is eafy tonbsp;conceive the reft.

Moft Kinds of Seeds muft be prepared, in order to difcover the minute Plants they contain, by fteeping them in warm Water tillnbsp;their Coats can be feparated and their femi-nal Leaves opened without Lacei'ation : tho�nbsp;fome new Sorts may better be diffe�led diy.nbsp;But Seeds, even without any Preparation, arenbsp;exceeding pretty Objects, and afford infinitenbsp;Varieties of Figure, Colour, andDecoration.

The Seeds of Strawberries rife out of the Pulp of the Fruit, and appear themfelvcsnbsp;like Strawberries when viewed.

Poppy Seeds (and what we call Maw-Seeds, which come from Germany^ and are produced by a Kind of Poppy) in Shape re-femble little Kidneys, but have Furrows ornbsp;Ridges on their Surfaces curioufly difpofednbsp;with regular Sides and Angles. From thefenbsp;Seeds a Duff may be fhaken, that looksnbsp;agreeable enough when brought before the

Microfcope; having nearly the fame Appearances as the Surfaces of the Seeds, with the Advantage of being tranfparent. This Duftnbsp;is really the fine Membranes that lay betweennbsp;the Seeds ; which, by the Prelfure of thenbsp;Seeds againft them, have received Marksnbsp;correfponding to the Ridges or Furrows onnbsp;the Seeds themfelvcs.

Seeds of the lelfer Moon wort, of Tobacco, Lettuce,Thyme,Chervil, Parfley,andathou-fand others, afford a delightfulEntertainment.

The Ancients imagined the capillaryPlants and many other Kinds to produce no Seedsnbsp;at all, and their Mifiake could never havenbsp;been redlified by the naked Eye: but thenbsp;Microfcope has ciifcovered, that all the feve-ral Species of Fern, Harts-tongue, Maidenhair, amp;c. are fo far from being barren innbsp;this refpedt, that they are amazingly fruitful : that the Seed-VefTels are on the Backsnbsp;of the Leaves, and that the Dufl which fliesnbsp;off when Vve meddle with them, is nothingnbsp;but their minute Seeds. Thefe Seed-Vcflelsnbsp;appear to the naked Eye like a black ornbsp;brown Scurf on the Back Side of the Leaf;nbsp;but, when viewed by the Microfcope, refem-ble little circular Tubes, divided into manynbsp;Cells containing Seeds. When the Seed isnbsp;ripe the Veffels fly open with a Spring, andnbsp;fpirt the Seeds out on every Side, in thenbsp;Form of Duft : and if at that Seafon foinenbsp;of the Leaves are put in a Paper Cone, and

that be held to the Ear, the Seed-VefTels may be heard to burft with a confiderable Noife.nbsp;Some of thefe minute VeiTels contain at lead;nbsp;an hundred Seeds, invifible to the nakednbsp;Eye.

It would be tedious to enumerate the Beauties of Seeds, fmce every tranfient Obferver muft be fenfible of their great Variety : butnbsp;I believe I fhali be excufed if I take Noticenbsp;of the Powder or Seed of the Fungus Fulve-rulentus or Puff-Ball, which, when cruflied,nbsp;feems to the naked Eye like a Smoke ornbsp;Vapour; but when examined by one of thenbsp;greatelf Magnifiers (for elfe it cannot be dif-tinguiflied) it appears to be infinite Numbers of little Globules of an Orange Colour,nbsp;fomewhat tranfparent, whofe Axis is notnbsp;above the fiftieth Part of the Diameter of anbsp;f lair: fo that a Cube of a flair�s Breadthnbsp;Diameter would be equal to an hu;.dred andnbsp;twenty-five thoufand of them. This was thenbsp;Powder of a Fungus bigger than two Fifis-jnbsp;but in another Sort, the Size (\fa Imaiiiappie,nbsp;the Globules were of a darker Colour, andnbsp;had each a little Stalk or Tail i hef ., arenbsp;evidently fo many minute Fuff-Balls, fur-niflied with Stalks or Tails to penetrate eafilynbsp;into the Ground : and the Mifchie�� they do

Leaves of Trees or Plants are full _� of innumerable Veins and Ramifications, that convey the perfpirable Juices tonbsp;the Pores, for their Difcharge. Whether ornbsp;no there be any Circulation in them is hill anbsp;Matter of Doubt but as their Juices, whennbsp;let out, immediately break, coagulate, andnbsp;become a ftiif Jelly, it feems probable therenbsp;may be foroe Circulation, which preventsnbsp;the fame Elfedt in the Vefifels. The fuddennbsp;Ihrinking, clofing, and opening of Flowers,nbsp;the raifing and finking the Heads of Poppies,nbsp;amp;c. the vermicular Motions of the Veins ofnbsp;Plants when expofed to the Air, feem alfo tonbsp;imply fjmewhat like Senfation. The Micro-fcope may perhaps be of Service to difcovernbsp;much more on thefe Subjedts than we yetnbsp;know.

* A Puff-Ball being burft near the Eyes of a Bny of twelve Years old, by an unlucky Piay-fellow, and the Dul t ereofnbsp;flying into them.occafioned fuch Swelling, I nfi anti motion, andnbsp;intenle Pain, with a continual Difcharge of Water, that henbsp;could not open them for feveral Days ; and did not recovernbsp;his Sight in lefs than a Fortnight, though all the Remediesnbsp;that could be thought on were applied. Vide Jon. Muys,nbsp;Fnx. Cbiriir, Ration. Obferv, I.

Mr. Leeuwenhoek, tearing to Pieces a Leaf of the Species of Box called Palmanbsp;Cereris, that he might examine it the better,nbsp;computed one Side of it to be furnhlied withnbsp;an hundred feventy-two thoufand and ninetynbsp;Pores; and as the other Side mud; have asnbsp;many, the whole Number of Pores in a finglenbsp;Leaf of Box will be three hundred forty-fournbsp;thoufand one hundred and eighty.

The Leaves of Rue feem full of Holes like a Honey-comb ; all the Kinds of St. John anbsp;Wort appear likewife duck full of Pin-holesnbsp;to the naked Eye j but the Microfcope fliews,nbsp;that the Places where thofe Holes feem to benbsp;are really covered with an exceeding thinnbsp;and white Membrane.

The Back Side of the Herb Mercury looks as if rough-cad with Silver, and the Ribs fullnbsp;of white round tranfparent Balls, like num-berlefs Grapes, fadened by dender Footdalks.

A Sage Leaf appears like Rug or Shag, fullofKnots tadeledwith Silver Thrums, andnbsp;embellilhed with fine round crydal Beads ornbsp;Pendants, fadened by little Footdalks.

The Backfide of a Rofe Leaf but efpe-cially of Sweet Briar, looks diapered with Silver

Prickles, that penetrate the Skin when touched, and occafion Pain, Heat, and Swelling : which Symptoms were imagined formerly to enfue from the Prickles being leftnbsp;in the Wounds they make. But the Micro-fcQpe difcovers fomething much more woh-derful in this common Vegetable, and fhewsnbsp;that its Prickles are formed and act in thenbsp;fame Manner as the Stings of living Animals,nbsp;For every one of them is found to be a rigidnbsp;hollow Body, terminating in the mofc acutenbsp;Point imaginable, with an Opening near itsnbsp;End. At the Bottom of this Cavity liesnbsp;a minute Velfel or Bag, containing a limpidnbsp;Liquor, which, upon the leaft touching ofnbsp;the Prickle, is fquirted thro� the little Outlet ; and, if it enters the Skin, produces thenbsp;Mifchiefs before-mentioned by the Pungency of its Salts. Hence it comes to pafs, thatnbsp;when the Leaves of Nettles are conliderablynbsp;dried by the Heat of the Sun, they fling butnbsp;very little : whereas fuch as are green andnbsp;juicy produce violent Pain and Inflammation. But the quite contrary to this wouldnbsp;happen, if the Symptoms were only owingnbsp;to the Breaking of the Prickles in thenbsp;Flefli : fince when dry they muft be morenbsp;brittle, as v/ell as more rigid, than whennbsp;they abound with Juice.

^lere, Are there any Valves in the Vef-fels of Vegetables, as in thofe of Animals, to let the Juices pafs, but hinder their Return ?

IT is I think agreed, that all Bodies have their Salts, from whofe different Configurations and Imprefiions many wonderfulnbsp;Changes are effedl�d both in Solids andnbsp;Fluids, in Things animate and inanimate.nbsp;Saline Particles ftriking upon the Nerves ofnbsp;Animals excite the Senfations of Tafte andnbsp;Smell and as their Forms and Degrees ofnbsp;Impulfe are almoft infinitely diverfified, thenbsp;Senfibility of Pain or Pleafure arifing therefrom muft be varied almoft infinitely, according to the greater or lefs Delicacy of thenbsp;Organs they ftrike upon.�It is therefore ofnbsp;great Confequence to difcover what we cannbsp;about ahem.

The Microfcope fhews, that Vinegar owes its Pungency to Multitudes of floating oblong quadrangular Salts, each of which, tapering from its Middle, has two exquifitelynbsp;lharp Ends. Thefe Salts, being inexprefliblynbsp;9nbsp;nbsp;nbsp;nbsp;..nbsp;nbsp;nbsp;nbsp;miqute.

minute, can hardly be difcovered, unlefs a Drop or two of Vinegar be expofed for fomenbsp;Hours to the Air, that the more watery Partnbsp;may evaporate, before we attempt to viewnbsp;them.

If Crabs Eyes are infufed in Vinegar^ after the Effervefcence is over, the Shapesnbsp;of the Salts will be found quite altered jnbsp;their tharp Points feem broken off, and theynbsp;appear in different fquare-like Forms, as atnbsp;Fig,. IL

In Wines of feveral Kinds the Salts are diftinguifliable, of various Figures, many ofnbsp;them refembling thofe^in Vinegar, but withnbsp;Ends much more obtufe: fome are thapednbsp;like a Boat, fome like a Spindle, others like anbsp;W eaver�s Shuttle, and others fquare : therenbsp;are alfo infinite Varieties of other Forms.

Vegetable Salts are to be extradled by burning the Wood, Stalks, or Leaves of anynbsp;Tree or Plant ; throwing the Athes intonbsp;Water j then filtering, and fetting the Liquor to cryftallize in .a cold Place. Theirnbsp;Oils alfo, when examined, prefent Abundance of Salts.

The Salts of Minerals or Metals are to be come at by quenching them, when red hot,nbsp;in Water, then filtering, evaporating, andnbsp;cryfiallizing.

Pretty Salts for Obfervation are, Pot-Afh, Englijh and Kujjian i Salt of Wormwood,nbsp;Saccharum Batumi, Salt of Tartar, Salt Ar-moniac. Salt of Hartfhorn, Salt of Amber,nbsp;^c. They fhould be examined firfl: in theirnbsp;dry or cryftallized State, and afterwards dif-folved in a very fmall Quantity of fomenbsp;tranfparent Fluid.

The Balts found in all Bodies, when fepa-rated by Fire, feem as fo many Pegs or Nails *, penetrating their Pores, and faften-ing their Parts together : but as Pegs ornbsp;Nails, when too large or too numerous,nbsp;ferve only to fplit or rend afunder; Balts, bynbsp;the fame Means, oftentimes break, feparate,nbsp;and diffolve, inftead of joining and makingnbsp;fall. Tney indeed are merely Inftruments,nbsp;and can no more ad: upon or force them-felves into Bodies, than Nails can without thenbsp;Stroke of a Plammer; but they are eithernbsp;driven on by the Preifure of other Bodies, ornbsp;by the Spring of the Air impelling them.nbsp;As Balts enter the Pores of all Bodies, Waternbsp;infinuates between the Particles of Balt; fe-parates or dilTolves, and fudains them in itsnbsp;Interftices, till, by being in a State of Reft,nbsp;they precipitate, and form themfeives intonbsp;Maftes. By this diftblving Power, Water

becomes

becomes the Vehicle of Salts, and conveys them into the Pores of Bodies, where itnbsp;leaves them to execute their proper Office.

Moft Sorts of Animal and Vegetable Salts are likewife probably dilTolved by the Juicesnbsp;of the Stomach, before they enter the Blood,nbsp;or they would cccafion great Mifehiefs : andnbsp;the Difficulty of diflblving forne mineralnbsp;Salts, or breaking off their Points in thenbsp;fame Manner, may be the Reafon of theirnbsp;dreadful Effeffs.

r I H E Microfeope may be of lingular Ser-S vice to determine, by ocular Examination, �what Kinds of Salts our medicinal Springs are charged with ; whence to formnbsp;a Judgment in what Cafes their Watersnbsp;may be drank to Advantage.

Alujn, Salt-petre, and Sea-falt : whereto he adds a fifth, lefs known, though more

pommon

Green Vitriol is produced from the Iron Pyrites. When mature and perfedb, its Cry-ilals are always pointed at each End, andnbsp;confift of ten Planes with unequal Sides: thatnbsp;is, the four middle Planes are Pentagons, andnbsp;each of the fliarp Ends is made up of threenbsp;triangular Planes, as Plate XIV. Fig. 4.

AhimhviXnt, diflblved in Water, and drained, affords Cryflals whofe Top and Bottom are two fexangular Planes, the Sides round,nbsp;which appear compofed of three Planes thatnbsp;are likewife fexangular, and three doublenbsp;quadrangular ones, placed alternately. Sonbsp;that every perfeft Cryftal confifts of elevennbsp;Planes, namely, five fexangular, and fixnbsp;quadrangular. Fig. V.

The Water of our Inland Salt-Springs affords Cryftals of an exadl cubical Form, one Side or Plane whereof feems to have a particular Clearnefs in the Middle, as if fomenbsp;Deficiency were in that Place �, but the othernbsp;five Sides are white and folid. See Fig. VI,

Sea-water boiled to Drynefs, and its Salt diffolved again in a little Spring-water, givesnbsp;Cryftals alfo that are cubical, but remarkably different from thofe laft defcribed : fornbsp;in the Cryjlals of Sea falt all the Angles ofnbsp;the Cube are fsemingly cut off, and the

Corners left triangular ; (See Fig. XL XI.) whereas the Salts of our Inland Springsnbsp;have all their Corners fharp and perfedl, asnbsp;Fig. VI.

Nitre, or Salt Petre, throws itfelf into long flender fexangular Cryftals, whofe Sidesnbsp;are Parallelograms. One End conftantlynbsp;terminates either in a pyramid-like Point, ornbsp;elfe in a fharp Edge, according to the Pofi-tion of the Sides of two unequal Planes.nbsp;The other End is always rough, and appearsnbsp;as if broken. Fig. VII. VIE

The moll general, tho� leafl noted of all the fojjile Salts among us, is a Kind of Wallnbsp;or calcarious Nitre, or Lime-falt, whichnbsp;may be colleded from the Mortar of ancientnbsp;Walls ', and is, as Dr. Lister fuppoles,nbsp;what a great Part of the Earth and Mountains conlift of*. Its Cryflals are flender andnbsp;long, the Sides of them four unequal Parallelograms: their Point at one End is formednbsp;of two Planes with triangular Sides �, thenbsp;other End terminates in two quadrangular

� We are well aflured, that in France it is the common Practice for thofe who have the Superintendency of the King�s Salt-Petre Works, to amafs vail Quantities of the Mortar andnbsp;Rubbilh taken from old Buildings: whence, by proper Management, they extraft Abundance of this calcarious Nitre.nbsp;And when they have got all they can from it, by letting it lienbsp;together for fome Years, it becomes impregnated anew, andnbsp;affords almoA as much as it did at hrll.

Planes:

Planes : though both Ends are feldom to be found unbroken,�Of this Salt fome is feennbsp;with five Sides, and all the other Varietiesnbsp;may be found in it, which are fliewn Fig.nbsp;VIII. I. 2. 3. 4. 5. 6. 7.

Unripe or imperfeft Vitriol is a white Salt, whofe Cryftals are Cubic Rhom-boides : as Fig. IX.

The Cryflals of our Inland Salt-fprings, not yet arrived at Maturity and Perfedlion,nbsp;are formed like Fig. X.

The Particles of each of thefe particular Salts, either in falling one upon another, ornbsp;uniting on one common Bafe, form them-felves into Maffes, which are invariable, andnbsp;always of the fame regular Figure : but it isnbsp;befi; to examine them in the fmallefl Maffes,nbsp;their Shape being there moft perfect andnbsp;diftindt.

IT has been urged by fome, in Behalf of fpontaneous Generation, that Worms arenbsp;found in the human Bowels, of a Figurenbsp;feen no where elfe ; and therefore that theynbsp;muft be generated there, fpontaneoufly, bynbsp;the Slime and Heat of the Inteftines: for ifnbsp;they proceed from Parents of their own Kind

without the Body,' and get into it by Acci-� dent, either in the Egg or any other State,nbsp;where are thofe Parents found?�This feemsnbsp;a very flrong Objedion ; but the Microfcopetnbsp;I believe, can enable us to anfwer it.

Worms found in the human Body are of three Kinds, namely, the Afcarides, or littlenbsp;fliort flender Maggots^ fo nearly refemblingnbsp;a Sort frequently met with in warm moiftnbsp;Places, under rotten Wood, amp;c. that theynbsp;may reafonably be fuppofed the fame.�Thenbsp;�Teretes rotundi, or long round Worms, whichnbsp;are evidently the Species of Earth-worms,nbsp;found commonly in Dunghills and Hotbeds; whofe Degree of Warmth is prettynbsp;equal to that of the human Bowels. Andnbsp;the Lati, Fafcics, Fape-worms, or 'Joint-worms, which are broad, flat, full of Joints,nbsp;and fometimes of a monftrous Length, extending many Yards along the Inteflines.�nbsp;This is the Animal faid to be found no wherenbsp;elfe ; but the Microfcope has very happilynbsp;difcovered Worms of the fame Figure exactly, and diff�rent in Size only, in the In-teftines of Eels, fo fixt as not to be removednbsp;without great Difficulty, but contrading andnbsp;dilating themfelves very agreeably Theynbsp;are of an Incredible Length in comparifon ofnbsp;their Breadth, and when contraded become

fix Times broader than when exhended. There are ape-worms like wife in the Bowels of a Hurbut, tho� fliorter than thofe innbsp;'Eels, and with a Head not quite the fame.nbsp;They are fixed to the Guts by a Kind ofnbsp;Hooks which they have in their Mouths,nbsp;and are not to be got off, but by holding thenbsp;Tail with one Hand, and feparating thenbsp;Head from the Inteftines with a Needle.

Having found thefe Worms in the Intef-tines of Fifhes, let us now eonfider how they could get there. And it is probable theynbsp;are naturally Water Animals, whofe Eggsnbsp;or young-ones getting into the Stomach withnbsp;the Water or the Food, become hatched ornbsp;nourifhed there. In the fame Manner theynbsp;may alfo be introduced into the Stomach ofnbsp;other Animals : and their Difference of Sizenbsp;in one or the other may arife from the different Degrees of Heat, and the Kinds ofnbsp;Nourifhment they meet with.�-Three othernbsp;Sorts of Worms are alfo found in the Intef-tines of Eels. Carp are likewife fubje�l tonbsp;Worms which make them very lean, and fonbsp;is the Erout.�There are two Sorts of whitenbsp;Worms in the Whiting; and the Microfcopenbsp;may difcovcr them perhaps in every othernbsp;Kind of Fifh : nor can we wonder at it,nbsp;when we refledt how liable Fifhes muft benbsp;to fwallow the Eggs or young-ones of whatever Infedts are Inhabitants of the Waters.

2. nbsp;nbsp;nbsp;There are frequently, in the Livers ofnbsp;Sheep, Animalcules thapcd like the Seed of a.nbsp;Gourd, or rather like a fmall thin Myrtle-Leaf with a very (hort Foot-ftaik. Theirnbsp;Colour is whitifhy but numberlefs branchingnbsp;Veffels or minute Canals of a greenilh Yellow are difperfed every where about themnbsp;and a round Hole �r Mouth appears near thenbsp;Stalk End, Thefe Creatures are found oftennbsp;in the Gall-Bladdert and in every Part ofnbsp;the Liver where, forming themfelves littlenbsp;Cells, they abide in a Liquor that is feem-ingly Blood mixt with Gall^.

Maggots are moft commonly to be met with, lodged ip a Cavity under the Tongue, nearnbsp;the Vertebra; where the Head joins on to thenbsp;Neck. Their Shape is partly cylindrical,,nbsp;being flat underneath, but rounded on thenbsp;tapper Side; in Colour white, with manynbsp;femi-annular Rings befet withdarkifli Hairs,nbsp;On the Head are a Couple of exceeding fmallnbsp;white Horns, which are thrufl: out or drawnnbsp;in like a Snail�s; and, under them two minute Claws,, black, hard, and Iharp, excitingnbsp;much Itching, and thereby great �nealinefs.nbsp;They move along by fixing thefe Claws, and

then dragging up their Bodies to them. The End where their Excrements are difehargednbsp;has a little Opening, with two black. Spotsnbsp;refembling a Half-moon. Twenty or thirtynbsp;are ufually found in one Head, of the Sizenbsp;of very large Maggots.

4. nbsp;nbsp;nbsp;Like to the foregoing, lefpecially towards the Tail, but fmaller, lefs vigorous,nbsp;and not fo hairy, are certain Maggots foundnbsp;in the ¹ Heads of Sheep. Their white Bodies are marked acrofs with black Lines (particularly the largeft of them); and two blacknbsp;Spots at the Anus, which form a Half-moonnbsp;in the Worms of Deer, compofe in thefe anbsp;complete Circle. They abide moft commonly in a hollow Part of the Os Frontis, nearnbsp;the Infertion of the Horns j but are fome-times found even in the Noftrils, and in thenbsp;Cavities round the Roots of the Horns.nbsp;Sometimes too they get higher up into thenbsp;Head, and make the Sheep run mad. Theynbsp;are lefs numerous than thofe in Deer, beingnbsp;feldom more than ten or fifteen.

5. nbsp;nbsp;nbsp;Early in the Spring Seafon, we lhallnbsp;frequently find flicking to Pales of Wood,nbsp;efpecially very old ones, and fometimes tonbsp;Walls of Brick or Stone, a Sort of little Wormnbsp;or Maggot, inclofed in a Cafe about the Big-

nefs of a fmall Barley Corn. If this Cafe be viewed with the Microfeope, it appears covered all over with a moft delicate Sort ofnbsp;Mofs, intermixed with fineSand orEarth. Atnbsp;the iliarpeft End there is a little Hole, thro�nbsp;which the Excrements are difeharged; andnbsp;at the other a larger Op�ning, where thenbsp;Creature puts out its Head, and faftens itfelfnbsp;to the Pales or Wall. The included Animal is all black, about two Lines of an Inchnbsp;long, and three Quarters of a Line broad.nbsp;Its Body has feveral Ringlets folding over onenbsp;another. Its Head is large, flat, and polifhed,nbsp;refembling Tortoife-fhell, with fome Hairsnbsp;ifluing from it ; and near thereto, on eachnbsp;Side, are three Legs. The Mouth is large,nbsp;and in continual Motion, and from it proceeds a flender Thread or Web : the Eyesnbsp;are black and round. This is a pretty Object, and changes I believe to fome Sort ofnbsp;minute Fly, tho� I have not had an Opportunity of making the Experiment.

6. Nothing is more common, in the Beginning of Summer, than to fee the Leaves of Peaches, Nectarines, and Cherries, curlednbsp;up and blighted: which Leaves on Examination are found covered with little InJeSls ¹,

Monf. De la Hire calls thefe Puctrons-, or little Fleas, and inftances them as Infedls that come from �walking tofiyiftgnbsp;without palling through the jiurclia State : which they ao bynbsp;�ply palling off their Skins, as a little Obfervation will Ihew.

fome blackifh, others green fome winged, and others without Wings. Thefe Creaturesnbsp;bring forth their Young alive and perfedt;nbsp;and if their Bodies be opened, feveral perfedlnbsp;Embryos will be feen therein.�It remains anbsp;Doubt, whence, and by what Means, thefenbsp;Infedls are conveyed upon the young fprout-ing Leaves, which at the fame Time are always covered with a glutinous and honey-likenbsp;Moifture : but we may hope diligent Obfer-vations will difcover this Secret to us. Treesnbsp;in this Condition are vifited by Multitudes ofnbsp;Ants; which hurt not the Trees, as fome er-roneoufly conjedlure, but do them Service,nbsp;by devouring this Vermin that infefls them.

7. The Ant itfelf is an Objcdl well worth our Notice, being a Creature of a very lingular Structure. The Head large, adornednbsp;with two pretty Horns, each having twelvenbsp;Joints. Its Eyes are protuberant and pearled : it has Jaws faw-like or indented, withnbsp;feven little Teeth that exadlly tally, openingnbsp;fide-ways, and able to gape very wide afun-der; by the Help whereof it is often feennbsp;grafping and tranfporting Bodies of three ornbsp;four Times its own Bulk and Weight. It isnbsp;naturally divided into the Head, the Breaft,nbsp;and the Belly or Tail ; each of thefe Partsnbsp;joining to the other by a very flender Ligament. From the Breaft-part, three Legsnbsp;come forth on either Side. The Tail is armednbsp;T 3nbsp;nbsp;nbsp;nbsp;with

with a Sting, which the Animal ufes only when provoked but then a poifonous Liquor is conveyed by it into the Wound, oc-cafioning Pain and Swelling. The wholenbsp;Body is cafed over with a Sort of Armour, fonbsp;hard as fcarce to be penetrated by a Lancet,nbsp;and thick fet with fliining whitifli Bridles.nbsp;The Legs, amp;c. are alfo covered with Hairs,nbsp;but much fmaller and of a darker Colour.

Upon opening an Ant-Hill^ we fhall fee them carrying in their Mouths, and fecuringnbsp;with great Solicitude, fmall whitifh Bodies,nbsp;ufually called their Eggs. Thefe, however,nbsp;are not Eggs, hyxlAnts, innbsp;nbsp;nbsp;nbsp;Aurelia Statet

each encompaffed with an Integument of its own fpinning. We might have conjeiflurednbsp;this from their Largenefs in Proportion to anbsp;perfeSi Ant; but the Microfcope fully provesnbsp;it, by difcovering to us their real Eggs, ofnbsp;an oblong oval Figure, about the Size of anbsp;Grain of Sand ¹ : ninety whereof would notnbsp;extend the Length of an Inch, nor an hundred and feventy be equal in Bignefs to onenbsp;of thef� Aurelia inclofed in its Cafe. Thefenbsp;minute Eggs produce Maggots, which, afternbsp;a Time, fpin themfelves Coverings, becomenbsp;Aurelias, and then Ants, The Parents Af-feftion for their Youngdn Aurelia Statenbsp;is fo drong, that when Danger threatensnbsp;they indantly run away with them, and'v^ill

fooner die than leave them. There are Several Sorts of Ants differing both in Size and Colour; and towards the End of Summernbsp;-many of them are feen having four Wings,nbsp;Thefe, Swammerdam fays, are Males *.

The French Academy has publidied a curious Account of Ants, whence I fhall abflrad; ibme few Particulars. Every Ant'amp; Neft (itnbsp;tells us) has a ftraight Hole leading into it,nbsp;about the Depth of Half an Inch ; which,nbsp;afterwards, runs Hoping downwards to thenbsp;public Magazine, where the Grains theynbsp;�colled; are ftored up �: and this is a differentnbsp;Place from that where they reft and eat.��nbsp;Their Corn, being kept under Ground, wouldnbsp;Ihoot and grow, did they not prevent it bynbsp;�biting out the Germen or Bud before they laynbsp;it up ; but this they conftantly do : for ifnbsp;their Corn be examined, no Btid will benbsp;found therein ; nor, if fowed in the Earth,nbsp;will it ever vegetate. Was it, however, tonbsp;lie continually in the Ground, the Moifturcnbsp;would occafion it to fwell and rot, and makenbsp;it unfit for Food. But thefe Inconvenienciesnbsp;they find Means to remedy by their Vigilancenbsp;and Labour in the following Manner.

They gather very fmall Particles of dry Earth, which they bring out of their Holes

every funfhiny Day, and place them in the Heat. Every one of them brings in hernbsp;Mouth a Particle of this Earth, lays it bynbsp;the Hole, and then goes to fetch another;nbsp;fo that in a Quarter of an Hour a vaft Number of fuch fmall Particles of dried Earthnbsp;are heaped round the Hole. Their Corn isnbsp;laid upon this Earth when under Ground,nbsp;and covered wdth the fame. When thefenbsp;Particles ofEarth are brought out, they fetchnbsp;out their Corn likewife, and place it roundnbsp;this Earth, making two tleaps about thenbsp;Hole, one of dry Particles of Earth, andnbsp;the other of Grains of Corn. Lall of all,nbsp;they fetch out the Remainder of their drynbsp;Earth whereon the Corn was laid. They never go about this Work unlefs the Weathernbsp;be clear, and the Sun very hot 3 but whennbsp;both are favourable, they perform it almoftnbsp;every Day.

The Author of this Account had found a Neil of Afits in a Box of Earth handing outnbsp;from a Window two Stories high 3 whencenbsp;they made Excurfons both upwards to thenbsp;Top of the Houfe, where fome Corn lay innbsp;a Garret 3 and downw'ards into a Garden,nbsp;wh^ch the Window overlooked. The Situation of this Neil obliged them to, go up ornbsp;down a great Way before they could poffiblynbsp;meet with any thing 3 but he found, not-withilanding, that none of them ever returned empty, but every one brought a Grain

of Wheat, Rye, or Oats, a fma^ Seed, or even a Particle of dry Earth, if nothing elfenbsp;could be got. Some travelled to th�,farthernbsp;End of the Garden, and, with prodigiousnbsp;Labour, brought heavy Loads from thence.nbsp;It required four Hours, as he learned by frequent Obfervation, to carry a pretty largenbsp;Grain or Seed from the Middle of the Gardennbsp;to the Neft; and he computed therefrom,nbsp;that an Ant works as hard as a Man whonbsp;fhould carrya heavy Load twelveMiles aDay.

The Pains thefe Ants took to carry Grains of Corn up a Wall to the fecond Story,nbsp;climbing all the Way with their Headsnbsp;downwards, muft be exceeding great. Theirnbsp;Wearinefs was fhewn by their frequent Stopsnbsp;at the moft conv^enient Places; and fomenbsp;appeared fo fatigued and fpent, they couldnbsp;not reach their Journey�s End : in which.nbsp;Cafe, it was common to fee the ftrongeftnbsp;Ants, which had carried home their Load,nbsp;come down again and help them. Sometimesnbsp;they were fo unfortunate to fall down withnbsp;their Burdens when juft in Sight of Home:nbsp;but when this happened, they feldom loftnbsp;their Corn, but carried it up again.�Henbsp;faw one, he fays, of the fmallefi Ants carrying a large Grain of Wheat with incrediblenbsp;Pains. When fhe came to the Box wherenbsp;the Neft was, fhe and her Load togethernbsp;tumbled back to the Ground. Going downnbsp;to look for her, he found fhe had recovered

the

the Grain, and was ready to climb up again. Ihe fame Misfortune befel her threenbsp;Times; but (he never let go her Hold, nornbsp;was difcouraged; till at lall;, her Strengthnbsp;failing, Ihe was forced to ftop, and anothernbsp;Ant affifted her to carry home her Load tonbsp;the public Stock.

How wonderful is the Sagacity of thele Jnfefts ! How commendable their Care, Diligence, and Labour 1 How generous theirnbsp;Affiftance of one another for the Service ofnbsp;the Community! How noble their publicnbsp;Virtue, which is never neglelt;9;ed for the Sakenbsp;of private Intereft ! In all thefe Things theynbsp;deferve our Notice and Imitation.�A contemplative Mind will naturally turn itsnbsp;Thoughts from the Condition and Government of Ant-hills to that of Nations ; andnbsp;refle�, that fnperior Beings may poffiblynbsp;conhder Human Kind, and all their Solicitudes and Toils, Pride, Vanity, and Ambition, with no more Regard than we do thenbsp;Concerns of thefe little Creatures.

8. Among Pinks, Rofes, and Sun-dowers, there is to be found, almoft conftantly, a Utile, long, nimble InfeB, fmaller than a Loufe,nbsp;fometimes creeping, and fometimes leaping.nbsp;It appears in the Microfcope bodied like anbsp;Walp, with fix or feven annular Divifions :nbsp;it has tvro fair long black and yellow Wings jnbsp;two Horns, each rifing from a knobbed

Root j two black Eyes, and fix Legs. It is fo tender, the lead: Touch kills it, but a verynbsp;pretty Objedt.

9. nbsp;nbsp;nbsp;Klittle InfeB is conftantly found in thenbsp;Froth (or Cuckow-Jpit as fome call it) thatnbsp;hangs on the Leaves of Rofemary, Lavender,nbsp;amp;c. It creeps firft, then leaps, and at laftnbsp;flies. It has fix Feet, with two blackhhnbsp;Claws at the End of each a long Probofcisnbsp;to fuck up its Food, two Horns, and a Pairnbsp;of darkifti red pearled Eyes. The Tailnbsp;ends in a Stump, but by its annular Divi-fions can be thruft out or drawn in at Plea-fure.

10. nbsp;nbsp;nbsp;There is a pvttiy yellow InfeB on Sycamore Leaves, with fix Legs, running verynbsp;nimbly. The Eyes are red, prominent, andnbsp;pearled j the Horns are flit, and forked atnbsp;the Ends. At firft it has no Wings, butnbsp;near the Shoulders are two little Protuberances, whence two long Wings come forth,nbsp;when it turns into a Fly or Locuft. It isnbsp;hairy towards the Tail.

11. nbsp;nbsp;nbsp;A fmall white oblong InfeB fticks tonbsp;the Ribs on the Back Sides of Rofe-treenbsp;Leaves, towards the End of Summer, whichnbsp;turns into a little yellow Locuft that fkipgnbsp;about the fame Tree. In both States it is anbsp;pretty Objedt.

12. There is alfo a greenifli Grafshoppernbsp;or Locuji, on Goofeberry-Leaves, Sweet-Bryar, and Golden Moufe-Ear, in Aprilnbsp;and May, with four Legs, two black Eyes,nbsp;a Pair of curious Horns, and many othernbsp;Beauties.

13. nbsp;nbsp;nbsp;In the Water of Ditches there arenbsp;frequently Numbers of JVater-Spiders, notnbsp;larger than a Grain of Sand ; they are verynbsp;voracious, hunting about continually fornbsp;Prey; and may be feen by the Microfeopenbsp;catching and devouring other minute Animalcules. Some have eight, fome ten Legs,nbsp;and AntemiceY\kG.Equifetum or Horfe-Tail.

14. nbsp;nbsp;nbsp;Likewife in Handing Waters we maynbsp;often meet with flender Eels or Worms,nbsp;about the third of an Inch, and fometimesnbsp;more, in Length. They are full of Jointsnbsp;from End to End, at large Diftances fromnbsp;one another; have a fharp Head like an Eel, anbsp;large Mouth, and two fine black Eyes. Thenbsp;Tail terminates in a Tuft of Hairs of a verynbsp;curious Stru�ure ; the Motions of the In-teftincs are feen diflindtly, and the wholenbsp;Animal is a delightful Obje�l.�The Blood-red ydinted Worm, very common in ftagnantnbsp;Waters, is alfo well deferving our Oblerva-tion.

15. nbsp;nbsp;nbsp;The Crane-Jly, called by Aldro-VAND Culex maximus, by Swammerdamnbsp;Tipula terrejlris, and by the common Peoplenbsp;Father-long-legs, affords, in every Part ofnbsp;it, agreeable Subjefts of Examination : butnbsp;the Feet are more particularly furprizing;nbsp;for, upon diffedting them in a Drop ofnbsp;Water, the fleffiy Fibres contradl and dif-tend, in a Manner not to be imagined without feeing it, and continue their Motionsnbsp;three or four Minutes. Mr. Leeuwenhoeknbsp;found it conftantly in the Feet of this Creature, but not in thofe of any other Infed *.nbsp;The Inteftines are alfo very curious, confift-ing of numberlefs Veffels and Organs, whichnbsp;may be feen as plainly by the Microfcope,nbsp;as the Bowels of larger Animals can by thenbsp;naked Eye -f*. The Tails both of the Malenbsp;and Female are of an extraordinary Structure: that of the Female ends in a fharpnbsp;Point, wherewith fhe perforates the Ground,nbsp;and depofits her Eggs under the Grafs innbsp;JVIeadows.

16. nbsp;nbsp;nbsp;The Multipes, or Scolopendra^ has anbsp;very long flender Bodyj its Mouth is armednbsp;with a Pair of fliarp Forceps, and in hotnbsp;Countries (where they are of a large Size)

its Bite is venomous : but our fmaller ones feem not mifchievous. One I examined hadnbsp;fifty-four Joints, and from every Joint a Legnbsp;ifl�ued on each Side, which, with two othersnbsp;at the End of the Tail, larger than the reft,nbsp;made in all one hundred and ten. Whennbsp;the Creatures move along, thefe Legs follow one another very regularly, making anbsp;pretty Kind of Undulation, not to be de-feribed, and giving the Body a fwifter Pro-greffion than one would expedt, where fonbsp;many Feet take fo many fhort Steps, in turn,nbsp;one after another. There are feveral Sorts ofnbsp;thefe Infedts, different in Shape, and innbsp;Number of Legs, which the Curious will benbsp;pleafed to examine

17. There is an extraordinary Sort of Caterpillar, of a middle Size, having fournbsp;Tufts of yellowifti white Hair, like littlenbsp;Brufties, of an equal Height, ftanding upright on its Back : below thefe, from eachnbsp;Side, iffues a Bunch of dark-coloured Hairsnbsp;of different Lengths, the Extremities ofnbsp;which are black. Two more Bunches ofnbsp;the fame Form rife from the Head likenbsp;Horns, and another ftill from the Top ofnbsp;the Tail. Every Hair in thefe Bunches,

*' Leevivenhoek fays, the Indian MilUpes has eight Eyes like the Spider, �iuere. Have En^iijh one� fet too i

when viewed through the Microfcopf, re-fembles a Peacock�s Feather, and is a delightful Objedl. The Inquifitive will find abundance more Wonders in this amazing;nbsp;Creature, and, indeed, in mofi: Sorts of Caterpillars.

18. The Silk-worm is a Creature every Part whereof, either in the Worm or Flynbsp;State, deferves our particular Attention :nbsp;but as both Malpighi and Leeuwenhoek have examined it with great Skillj,nbsp;and publilhed their Obfervations with anatomical explanatory Drawings, I fhall refernbsp;the Curious to them, and to their own Enquiries ; only advifing fuch as fhall engagenbsp;in a farther Examination, not to negle�l thenbsp;Skins thefe Animals cafl; off three Timesnbsp;before they begin to fpin : for the Eyes,nbsp;Mouth,Teeth, Ornaments of the Head, andnbsp;many other Parts, may be difcerned betternbsp;jn the caji-off Skins than in the real Animal. A due Obfervation of the Changesnbsp;of this Creature, from the Caterpillar to the.nbsp;Nymph, Aurelia, or Chryfalis, and thencenbsp;to the Moth or Butterfy State, will give anbsp;general Notion of the Changes all Caterpillars undergo, though fome little Differencesnbsp;may be in the Manner. Swammerdamnbsp;fays, the Bufterjly, by a judicious Examination, may be traced and difcerned under

19. The Tail of the Male Silk-worm being Squeezed, Animalcules were found in the Semen¹ four Times as long as broad j theirnbsp;Backs thicker than their Bellies, like thenbsp;Shape of a Trout, Their Length was fup-pofed to be about half the Diameter of anbsp;Hair. This I experienced myfelf, on thenbsp;8th Day of Auguji, in the Year 1742, when,nbsp;taking a Male Silk-worm, that was juft thennbsp;come forth in its Moth-Jlate, and giving itsnbsp;Tail feveral little gentle Squeezes, in aboutnbsp;a Minute�s Time a fmall Drop of a brownifhnbsp;white Liquor was fquirted brifkly from it onnbsp;a Talc I held to receive it: and diluting thisnbsp;with a little Water warmed in my Mouthnbsp;for that Purpofe, I was very much furprizednbsp;and pleafed to obferve the numberlefs Animalcules it contained, fwimming about, alivenbsp;and vigorous.-

of a Watch, ferves both for Mouth and Tongue, by entering into the Hollows ofnbsp;Flowers, and extra�cing their Dews andnbsp;Juices. The Shape and Strufture of it willnbsp;be found very furprizing.

21. nbsp;nbsp;nbsp;The Legs and Feet of InfeSis are wonderful in their Strufture and Contrivance,nbsp;according to their different Circumftancesnbsp;and Neceffities of Life, and afford a pleafingnbsp;Variety of Objects. It is pretty to obferve,nbsp;not only the diarp hooked Claws, but alfonbsp;the fkinny Palms of fome Flies, ^c. whichnbsp;enable them to walk on Glafs and othernbsp;fmooth Surfaces, even with their Bodiesnbsp;hanging downwards, by means of the Pref-fure of the Atmofphere ; others again have anbsp;Sort of Spunges, which preferve their Clawsnbsp;from being broken or blunted by firikingnbsp;againft hard Bodies, as the Claws of Cats, amp;c.nbsp;are, by foft flefhy Protuberances at the Bottoms of their Feet.

22. nbsp;nbsp;nbsp;The Nymph of the Clothes-moth, whichnbsp;(from being often found fcudding amongnbsp;Books and Papers) Mr. Hook calls the fil-ver-coloured Book-worm, is covered withnbsp;thin tranfparent Scales, from whofe Surfaces a Multiplicity of Refledrions of Lightnbsp;make the Animal appear in Colour like anbsp;fine Pearl. It has fix Legs, runs by Startsnbsp;and Stops, and has three Horns at the Ex-

tremity of the Tail. As this Defcription is fufEcient to make it known, I ihall leavenbsp;the Curious to examine its Beauties, and notnbsp;anticipate their Pleafure. Vide Hook�s Mi-crog. p. 208.

23. nbsp;nbsp;nbsp;On the Leaves of Orange Trees, Fignbsp;Trees, Willows, and many other Trees andnbsp;Plants, there are various Kinds of minute In-J��fs, as yet but little known, inclofed innbsp;Tubercles or Swellings.

24. nbsp;nbsp;nbsp;The Eggs of InfeSis are remarkable fornbsp;their different Figure and Colour, and fornbsp;the particular Regularity and Exadlnefsnbsp;wherewith they are frequently placed. Wenbsp;fhall fometimes find a Sort cemented roundnbsp;a Twig of the Sloe Tree, or DamfonTree, asnbsp;if faftened there by Art, and ranged merelynbsp;for the Sake of Beauty. The Variety of themnbsp;is inconceivable, and tolt; be fought for asnbsp;well in the Waters as elfewhere i as thofenbsp;will be convinced who will take the Painsnbsp;to examine, in the Spring, the Water-Crefifes,nbsp;Brook-lime, and other Water-plants, on thenbsp;Back of whofe Leaves infinite Numbers ofnbsp;minute Eggs may frequently be difcovered,nbsp;appearing to the naked Eye only as a Slime.

25. nbsp;nbsp;nbsp;In Cellars, on the Corks of Bottles,nbsp;there are three or four Sorts of very furpriz-ing Infe�ls.

26. The

26. nbsp;nbsp;nbsp;The Lungs of a Frog, blown up andnbsp;dried, will affift us to difcover the truenbsp;Structure of that Bowel.

27. nbsp;nbsp;nbsp;Cochineal, which comes from Newnbsp;Spain, and is fo valuable for its Ufe in dyingnbsp;Scarlet, Crimjon, and Purple, has been af-ferted by fome to be a Seed or Grain, andnbsp;by others, an Infedt; but the Microfcope determines thefe Difputes, by fhewing plainly,nbsp;after fteeping it in Water twenty-four Hours,nbsp;an oval Body, Scales, Legs, and a pointednbsp;Trunk: in Ihort, the whole refembles ournbsp;Cow-lady. Many Eggs may be difcoverednbsp;upon opening their Bodies : and if you burnnbsp;them, let their Alhes ftand two or threenbsp;Days in Water, then filter and evaporate,nbsp;their Salts may be difiindlly feen.

28. nbsp;nbsp;nbsp;The Feathers of Birds afford Varietynbsp;of Beauty, and diffT greatly from one another, not only in their general Colour andnbsp;Form, but in the Strudture of each particular Part j as every body muft be lenlible,nbsp;who examines thofeof the Oftrich, the Peacock, the Eagle, the Swan, the Parrot, thenbsp;Owl, and all the numerous Species of Birds.nbsp;Their Quills too delerve our Attention : andnbsp;our Obfervations on them will be affifted bynbsp;reading the 3�thObfervation in Mr. Hook�snbsp;Micrography, p. 168; and alfo Mr. Leeu-

29. nbsp;nbsp;nbsp;MoJJes of all Kinds are agreeable Ob-jefts, and appear, by the Microfcope, to be asnbsp;perfect in their Leaves, Flowers, and Seeds,nbsp;as the largeft Plants or Trees. Thofe, particularly, that grow on the Rocks and Coaftsnbsp;of the Sea, exhibit amazing Beauties.

30. nbsp;nbsp;nbsp;Spunge is reckoned a Elant-Animal,nbsp;and appears compofed of minute Veffels re-fembling Veins and Arteries.

31. nbsp;nbsp;nbsp;Decayed Fruits, moift Wood, dampnbsp;Leather, flale Bread, and Abundance of othernbsp;Things, contrad: what we call Mouldinefs;nbsp;which the Microfcope difeovers to be nothingnbsp;elfe but innumerable minute Plants, bearingnbsp;Leaves, Flowers, and Seeds, and increaling innbsp;a Manner almofl incredible : for in a verynbsp;few Hours the Seeds fpring up, arrive at fullnbsp;Maturity, and bring forth Seed themfelves ;nbsp;fo that a Day produces feveral Generations ofnbsp;them. There are many Sorts of thefe micro-fcopical Plants, very different in Size andnbsp;Appearance: Some of the Mufhroom Kind,nbsp;others refembling Bulrufhes, and othersnbsp;again bearing vaft Quantities and great Varieties of Fruit. Other Kinds are likewife foundnbsp;in great Abundance on the Surface of Liquors, when they are what we term Mothery,

32. nbsp;nbsp;nbsp;'Tht Air-veJ/�ls, Sap-vejfels, andP^jmnbsp;of Wood, are wonderful in their Figure,nbsp;Number, andDifpolition as plainly appearsnbsp;by Ibaving off the thinned: Slices poffible,nbsp;lengthways, croffways, and obliquely, andnbsp;bringing them to view. Fir and Cork arenbsp;the readied; for this Purpofe : but all othernbsp;Kinds of Wood, tho� with fomewhat morenbsp;Trouble, may be rendered fit to be examined. In a Piece of Cork, no longer thannbsp;the eighteenth Part of an Inch, fixty Cellsnbsp;were numbered in a Row; whence it follows, that one thoufand and eighty are innbsp;the Length of an Inch ; one million an hundred fixty and fix thoufand four hundred innbsp;an Inch fquare ; and in a Cubic Inch, onenbsp;thoufand two hundred fifty-nine millionsnbsp;feven hundred and twelve thoufand'*.

In the Idith of Trees and Plants, cut fo as to become tranfparent, the Vefiels may benbsp;difcerned didindtly. The Pores of Woodnbsp;may likewife be feen advantageoudy in Cbar-gt;nbsp;coal and Small-coal.

33. nbsp;nbsp;nbsp;There are many Sorts of Sand ; fomenbsp;gathered on the Sea-fhore, or on the Shoresnbsp;of Rivers, and others found within Land.nbsp;The Grajns of each Sort differ much in Size,

U 3

Form, and Colour : fome are opake, others tranfparent; fome have rough Surfaces, andnbsp;others are quite fmooth ¹. Thefe Varietiesnbsp;are very agreeable to examine by the Micro-fcope, which fhews, in fome of the fhiningnbsp;Kinds, Grains having all Numbers of Sidesnbsp;and Angles, and fo finely polifhed, that nonbsp;Diamond is more exquifitely beautiful. Onnbsp;others, grotefque Figures, orReprefentationsnbsp;of Landfcapes, Buildings, Plants, and Animals, at once furprize and pleafe.

34. In order to examine Diamonds quot;f- with the greater Exadtnefs, Mr. Leeuwenhoek:nbsp;broke a fmall one be tween two Hammers,nbsp;and placing the Pieces before his Microjeope,nbsp;in the Sun-flaine, he faw many fparklingnbsp;Flames iffue from them, with a continualnbsp;Corrufeation in fome, like a faint Lightning.nbsp;Then viewing them in the Shade, he obferv-ed, among o Jier pretty Appearances, a littlenbsp;Flame that feemed to dart from each Particlenbsp;of the Diamond : and it was a glorious Sightnbsp;to behold Muiritudes of fparkling Flames,nbsp;mod of a bright Fire-colour, and othersnbsp;greenifli, flafhing faintly and like Lightningnbsp;at a Diftance. In other Pieces of the Dta-

Vid, Phil. Tranf. Numb. 289. Hook�s Miirog- p. 80. f Vid. Phil. Tra�/. Numb. 374. ^

mond, the Lamellce, or Layers, compofing it, were very plainly to be diftinguilhed.

35. nbsp;nbsp;nbsp;In flriking Fire with a Flint and Steel,nbsp;little Particles of Steel are ftruck off, andnbsp;melted into Globules by the Collifion ; asnbsp;will be evident upon making the Experimentnbsp;over a Sheet of white Paper, and viewingnbsp;what falls into it through the Microfcope.nbsp;Mr. Hook firft made the Trial, and foundnbsp;that a black Particle, no bigger than a Pin�snbsp;Point, appeared like a Ball of poliflaed Steel,nbsp;and flrongly refledted the Image of thenbsp;Window near which he examined it *. Itnbsp;is alfo entertaining enough to feparate thenbsp;melted Iron Particles from the Particles ofnbsp;Stone, which fometimes are vitrified, bynbsp;Means of a Knife that has been touched bynbsp;a Loadftone.

36. nbsp;nbsp;nbsp;Kind Nature has fupplied the Seeds ofinbsp;Dandelion, Thiftles, and many other Plants,nbsp;with a Down, that ferves inftead of Wingsnbsp;to convey them to diftant Places. The Figures of fuch Down, in different Plants, arenbsp;very different when looked at thro� Glafifes jnbsp;fome appearing plain and fmooth, othersnbsp;rough and thorny, and others again withnbsp;little Hooks or Clafpers to catch hold of any

U 4 nbsp;nbsp;nbsp;Thing.

Thing. Peach.:s, Quinces, and feme other Fruits, have likewife a loft Down, which isnbsp;worth examining, as well as the Hairs onnbsp;many Sorts of Leaves, Fruits, and Seeds.

37. nbsp;nbsp;nbsp;There is a very fine Down, or Hair,nbsp;called Cowage, or Cow-itch, growing on anbsp;Sort of hairy Kidney-bean that comes fromnbsp;the Eajl-Indies. The Pods, about threenbsp;Inches long, refemble a French-be an, andnbsp;are covered with this Down, or Hair, whichnbsp;is very ftifF for its Bignefs, crufes Pain andnbsp;Inflammation if rubbed on any Part, andnbsp;when viewed by a Microfeope appears likenbsp;Multitudes of Needles.

A Sort of curling Horns, rifing out of the Middle of fome Carnations and Pinks, arenbsp;exceeding pretty Objeds.

38. nbsp;nbsp;nbsp;The Flakes of falling Snow are variousnbsp;in their Configurations, and extremely beautiful, if examined before they melt : whichnbsp;may eafily be done by making the Experiment in the open freezing Air. Descartes,nbsp;Dr. Gr�w, Mr. Hook, Mr. Morton, Dr.nbsp;Langwith, and others, have given ns fe-veral of their difieient Star-like P'orms ; andnbsp;Dr; Stocke, of Zealand, has k.tely communicated to the Royal Society fome newnbsp;Figures unobferved before.

The Configuration of the Particles of Dew may perhaps be likewife well worth cbferv-ing.nbsp;nbsp;nbsp;nbsp;Plumous

Plumous Alum, Talcs of different Kinds, Afbeftos, Marcafites, and all Sorts of Minerals and Foffils, afford a Variety of agreeable,nbsp;and carious Obj 'dts.

i�ithiops Mineral, Calomel, Mercurius dulcis, and all other Mercurial Powders, arenbsp;found, when examined by the Microfcope,nbsp;to be full of minute Globules of crude andnbsp;unaltered Mercury.

Common Salt diffolved in Water exhibits infinite Numbers of quadrangular Bodies.

Toads, Frogs, and Newts, are killed by rubbing Salt upon their Backs ¹ j Snakes,nbsp;Vipers, Rattle - Snakes, amp;c. by drawingnbsp;through their Skin, with a Needle, a Threadnbsp;dipped in Oil of Tobacco : and Mercury isnbsp;a mortal Poifon to Ants.

It would be an endlefs. Talk to point out half the Objedts fit to be examined by thisnbsp;ufeful and entertaining Inffrument, whichnbsp;fupplies us, as it were, with Eyes infinitelynbsp;more penetrating than our own; and difco-vers VVonders to us which we fhould be unable to conceive vx ithout it. The foregoingnbsp;are a few only among thofe that are moftnbsp;curious j but every Creature, every Plant,nbsp;and bruit, and Flower, every Drop of Wa-

ter, and every Particle of Matter, if carefully examined, will afford us new Inftrudion andnbsp;Delight.

EFORE this Treatife is concluded, it will not perhaps be thought unprofitable to examine fome of the fined; andnbsp;mofl exquifite Performances of human Art,nbsp;and compare them with the Produftions ofnbsp;Nature : as fuch a Comparifon muft tendnbsp;towards humbling the Self-conceit and Pridenbsp;of Man, by giving him a more reafonablenbsp;and modeft Opinion of himfelf; and at thenbsp;fame Time may in fome Degree conduce towards improving his imperfedl Conceptionsnbsp;of the Supreme Creator.

Upon examining the Edge of a very keen Razor by the Microfcope, it appeared asnbsp;broad as the Back of a pretty thick Knife jnbsp;rough, uneven, full of Notches and Furrows, and fo far from any Thing like Sharp-nefs, that an Infirument as blunt as thisnbsp;feemed to be, would not ferve even to cleavenbsp;Wood *.

An exceeding fmall Needle being alfo examined, the Point thereof appeared above a Quarter of an Inch in Breadth ; not round,nbsp;or flat, but irregular and unequal; and thenbsp;Surface, though extremely fmooth and brightnbsp;to the naked Eye, feemed full of Rug-gednefs. Holes, and Scratches. In (hort,nbsp;it refembled an Iron Bar out of a Smith�snbsp;Forge ¹.

But the Sling of a Bee, viewed through the fame Inftrument, (hewed every where anbsp;Polifh mo(l amazingly beautiful, withoutnbsp;the lea(l Flaw, Blemifli, or Inequality j andnbsp;end^d in a Point too fine to be difcerned :nbsp;yet this is only the Cafe, or Sheath, of In-(Iruments much more exquifite containednbsp;therein, as before defcribed. Page 210.

A fmall Piece of exceeding fine Lawn appeared, from the large Diftances and Holes between its Threads, fomewhat like a Hurdle or Lattice, and the Threads themfelvesnbsp;feemed coarfer than the Yarn wherewithnbsp;Ropes are made for Anchors.

Some BruJJels l.ace, worth five Pounds a Yard, looked as if it were made of a thick,nbsp;rough, uneven Hair Line, intwifled, faften-ed, or clotted together in a very aukwardnbsp;and unartful Manner.

But a Silkworm s Web, being examined, appeared perfedlly fmooth and ihining, everynbsp;where equal, and as much finer than anynbsp;Thread the bell: Spinfter in the World cannbsp;make, as the fmalleft Twine is finer thannbsp;the thickeft Cable. A Pod of this Silk beingnbsp;wound off, was found to contain nine hundred and thirty Yards : but it is proper tonbsp;take Notice, that as two Threads are glewednbsp;together by the Worm through its wholenbsp;Length, it makes really double the abovenbsp;Number, or one thoaiand eight hundrednbsp;and fixty Yards : which being weighed withnbsp;the utmoif Exacflnefs, were found no heaviernbsp;than two Grains and a Half^k What annbsp;exquifite Finenefs is here ! arid yet this isnbsp;nothing when compared with the Web of anbsp;fmall Spider (fee Page 200), or even withnbsp;the Silk that iflued from the Mouth of thisnbsp;very Worm, when but newly hatched fromnbsp;the Egg.

The fmalleft Dot, T�ittle, or Point, that can be made with a Pen, appears, whennbsp;viewed by the Microfcope, a vaft irregularnbsp;Spot, Tough, jagged, and uneven all aboutnbsp;its Edges, and far enough from being trulynbsp;round. The fineft and minuteft Writing,nbsp;fuch as the Lord�s Prayer in the Compafsnbsp;of a filver Penny, or other fuch like curious

Performance, done by the moft able Mafter, feems, when brought to Examination, asnbsp;fhapelefs, uncouth, and barbarous, as if widt-ten in Runic CharaSlers. But the little Specksnbsp;on the Wings or Bodies of Moths, Beetles,nbsp;Flies, and other Infedts, are found, whennbsp;magnified, to be mod: accurately circular :nbsp;and all the other Lines and Marks aboutnbsp;them appear regularly and finely drawn, tonbsp;the utmofl Poffibility of Exadtnefs.

Dr. Power fays, he faw a golden Chain at Tredescant�s, of three hundred Links,nbsp;not more than an Inch in Length, faftenednbsp;to, and pulled away by, a Flea. And Inbsp;myfelf have feen very lately, near Durharn-Yard in the Strand, and have examined withnbsp;my Microfcope, a Chaife (made by one Mr.nbsp;Boverick, a Watch-maker) having fournbsp;Wheels, with all the proper Apparatus belonging to them, turning readily on theirnbsp;Axles; together with a Man fitting in thenbsp;Chaife; all formed of Ivory, and drawn alongnbsp;by a Flea without any feeming Difficulty. Inbsp;weighed it with the greateft Care I was able,nbsp;and found the Chaife, Man, and Flea, werenbsp;barely equal to a fingle Grain. I weighednbsp;alfo, at the fame Time and Place, a Brafsnbsp;Chain made by the fame Hand, about twonbsp;Inches long, containing two hundred Links,nbsp;with a Hook at one End, and a Padlock and

We are told, that one Oswald Nelin-GER �f made a Cup of a Pepper-corn, which held twelve hundred other little Cups, allnbsp;turned in Ivory, each of them being gilt onnbsp;the Edges, and Handing upon a Foot: andnbsp;that, fo far from being crowded or wantingnbsp;Room, the Pepper-corn would have heldnbsp;four hundred more.

Thefe are fome of the niceft, moft curious, and furprizing Works of Art: but let usnbsp;examine any of them with a good Micro-fcope, and we fhall immediately be convinced, that the utmoft Power of Art is onlynbsp;a. Concealment of Deformity, an Impofitionnbsp;upon our Want of Sight; and that our Admiration of it arifes from our Ignorance ofnbsp;what it really is.

This valuable Difeoverer of Truth will prove the moft boafted Performances of Artnbsp;to be as ill-fhaped, rugged, and uneven, as

I have feen, fince mv wrking the above (made by the fame Artifl) a Qu drilie Table with a D.awer in it, an Eating Table, a b de-board Table, a Looking glafs, twelvenbsp;Chairs with Skeleton Backs, two dozen of Plate-, fix Difhes,nbsp;a dozen Knives and as many Forks, twelve Spoons, two Salts,nbsp;a Frame and Callers, together with a G'ntleman, Lady, andnbsp;Footman, all contained in a Cbtrry Stone, and not fillingnbsp;much more than half of it.

if they were hewn with an Ax, or ftruck out with a Mallet and Chiffel. It will Ihewnbsp;Bungling, Inequality, and Imperfedtion innbsp;every Part, and that the Whole is difpropor-tionate and monftrous. Our fined: Miniaturenbsp;Paintings appear before this Inftrument asnbsp;mere Daubings, plaiftered on with a Trowel,nbsp;and entirely void of Beauty, either in th�nbsp;Drawing or the Colouring. Our moft fhin-ing Varniihes, our fmootheft Polifhings,nbsp;will be found to be mere Roughnefs, full ofnbsp;Gaps and Flaws.

Thus fink the Works of Art, when we become enabled to fee what they really are !� But, on the contrary, the nearer we examine,nbsp;the plainer we diftinguifh, the more we cannbsp;difcovcr of the Works of Nature, even in thenbsp;leaft and meaneft of her Productions, thenbsp;more fenfible we muft be made of the Wif-dom. Power, and Greatnefs of their Author.nbsp;�Let us apply the Microfcope where wenbsp;will, nothing is to be found but Beauty andnbsp;Perfection. View v/e the numberlefs Species of InfeCts that fwim, creep, or fiy aroundnbsp;us, what Proportion, ExaCtnefs, Uniformity,nbsp;and Symmetry fhall we perceive in all theirnbsp;Organs ! what a Profufion of Colouring!nbsp;Azure, Green, and Vermilion, Gold, Silver,nbsp;Pearls, Rubies, and Diamonds j Fringe andnbsp;Embroidery on their Bodies, Wings, Heads,nbsp;and every other Part! How rich the Glow!

how high the Finifhing ! how inimitable the Polifh we every where behold !�Searchnbsp;we yet farther, and examine the Animalcules, many Sorts whereof it would be im-poffible for an human Eye unaffifted to dif-cern; thofe breathing Atoms, fo fmall theynbsp;are almoft all Workmanlliip ! in them toonbsp;we �hall difeover the fame Organs of Body,nbsp;Multiplicity of Parts, Variety of Motions,nbsp;Diverdty of Figures, and particular Ways ofnbsp;Living, as in the larger Animals.�Hownbsp;amazingly curious muft the internal Structure of thefe Creatures be ! The Heart, thenbsp;Stomach, the Entrails, and the Brain ! Hownbsp;minute and fine the Bones, Joints, Mufcles,nbsp;and Tendons ! How exquifitely delicate beyond all Conception the Arteries, Veins,nbsp;and Nerves! What Multitudes of Veffelsnbsp;and Circulations muft be contained withinnbsp;this narrow Compafs ! And yet all havenbsp;fufficient Room to perform their differentnbsp;Offices, and neither impede nor interferenbsp;with one another.

The fame Order, Regularity, and Beauty, will appear likewiie among Vegetables, ifnbsp;brought to Examination. Every Stalk, Bud,nbsp;Flower, or Seed, difplays a Figure, a Proportion, a Harmony, beyond the Reach of Art.nbsp;There is not a Weed, not a Mofs, whofenbsp;every Leaf does not (hew a Multiplicity ofnbsp;Velfels and Pores difpofed mofl curiouilynbsp;for the Conveyance of Juices to fupport

and nourifli it, and which is not adorned with innumerable Graces to embellilh it.

The mod perfedt Works of Art betray a Meannefs, a Poverty, an Inability in thenbsp;Workman; but thofe of Nature plainlynbsp;prove, the Hand that formed them was ab~nbsp;folute Mafter of the Materials it wroughtnbsp;upon, and had Tools exactly fuitable to itsnbsp;Delign. Every Hair, Feather, or Scale, eveanbsp;of the meaneft Infedl, appears rounded, po-lifhed, and finifhed to the higheft Pitch jnbsp;and Ihews the abundant Riches, Munificence, and Skill of its Maker.

But fome may poffibly enquire, to what Purpofe Providence has bellowed fuch annbsp;Expence of Beauty on Creatures fo inlignifi-cant; and then cry out. What is all this tonbsp;us ? � My Reply is, that the Beauty andnbsp;Elegance which adorn them are evident andnbsp;convincing Proofs of their not being fo infg-nificant as we prefumptuoully fuppofe theynbsp;are; for fuch Beauty mull be given them,nbsp;either for their own Sake, that they them-felves may be delighted with it; or elfe fornbsp;ours, that we may obferve in them thenbsp;amazing Power and Goodnefs of the Creator,nbsp;If the former be the Cafe, we mud allownbsp;them to be of Confequence in the Accountnbsp;of their Maker, and therefore deferve ournbsp;Regard; and if the latter, it is really ournbsp;Duty to take Notice of and admire them. Butnbsp;VoL. I,nbsp;nbsp;nbsp;nbsp;Xnbsp;nbsp;nbsp;nbsp;for

for whatever Reafon God has been pleafed to beftovv Exiftence on them, and to clothenbsp;them with Beauty, what he has judged worthy himfelf to create, is not, furely, belownbsp;us to examine and confider. The famenbsp;Eland that formed the Whale, the Elephant,nbsp;and the Lion, has likewife made the Loufe,nbsp;the Gnat, and the Flea.

The Ufe of Microfcopenaturally lead a thinking Mind to a Confi-deration of Matter, as falhioned into different Figures and Sizes, whether Animate or Inanimate : it will raife our Refledlions from anbsp;Mite to a Whale, from a Grain of Sand tonbsp;the Globe whereon we live j thence to thenbsp;Sun and Planets ; and, perhaps, onwards ftillnbsp;to the fixt Stars and the revolving Orbs theynbsp;enlighten, where we (hall be loft amongftnbsp;Suns and Worlds in the Immenfity and Magnificence of Nature.

Our Ideas of Matter, Space, and Dura-tion, are merely comparative, taken from ourfelves and Things around us, and limitednbsp;to certain Bounds ; beyond which if wenbsp;endeavour to extend them, they become verynbsp;indiftindl. The Beginnings and Endings,

exceffive Greatnefs or exceffive Littlenefs, of Things, are to us all Perplexity and Confu-fion.

� Let a Man try to conceive the differ-� ent Bulk of an Animal which is twenty, from another which is an hundred Timesnbsp;� lefs than a Mite j or to compare, in hisnbsp;� Thoughts, the Length of a thoufand Dia-� meters of the Earth with that of a million,nbsp;�an he will quickly find that he has nonbsp;� different Meafures in his Mind adjuftednbsp;� to fuch extraordinary Degrees of Grandeurnbsp;� or Minutenefs. The Underflanding, in-� deed, opens an infinite Space on every Sidenbsp;� of us but the Imagination, after a fewnbsp;� faint Efforts, is immediately at a Stand,nbsp;** and finds itfelf fwallowed up in the Im-� menfity of the Void that furrounds it.nbsp;� Our Reafon can purfue a Particle of Mat-� ter thro� an infinite Variety of Divifions,nbsp;� but the Fancy foon lofes Sight of it, andnbsp;� feels in itfelf a Kind of Chafm, that wantsnbsp;� to be filled with Matter of a more fenfiblenbsp;Bulk. We can neither widen nor con-� traft the Faculty to the Dimenfions ofnbsp;� either Extreme. The Objedt is too bignbsp;for our Capacity, when we would com-� prehend the Circumference of a World;nbsp;� and dwindles to Nothing when we en-� deavour after the Idea of an Atom

The minute Size of microfcopical Animalcules, and the little Space they occupy, when compared with ourfelves and the Roomnbsp;we fill, may poffibly increafe our Pride andnbsp;F'olly, and make us imagine ourfelves ofnbsp;mighty Confequence in the Creation. Butnbsp;if we carry our Thoughts upwards, andnbsp;compare the Body of a Man to the Bulk ofnbsp;a Mountain, that Mountain to the wholenbsp;Earth, the Earth to the Circle it defcribesnbsp;round the Sun, that Circle to the Sphere ofnbsp;the fixt Stars, the Sphere of the fixt Stars tonbsp;the Circuit of the whole Creation, and thenbsp;whole Creation itfelf to the infinite Spacenbsp;that is every where diffufed about it, we

� * Were the Sun, with all its planetary � Worlds, utterly extinguiflied and annihi-� lated, they would no more be miffed innbsp;the grand Univerfe than a Grain of Sandnbsp;� upon the Sea-fhore : the Space they pof-� fefs is fo exceeding little, in comparifonnbsp;� of the Whole, that it would fcarce makenbsp;a Blank in the Creation. The Chafm

** would be almoft imperceptible to an Eye � that could take in the whole Compafs ofnbsp;� Nature, and pafs from one End of thenbsp;� Creation to the other.� What then is

A Mite upon a Cheefe is as large and confiderable, in Proportion, as a Man uponnbsp;the Earth : the little Infedts feeding on thenbsp;Leaves of Peach-Trees and Cherry-Trees,nbsp;are no ill Reprefentation of Oxen grazing innbsp;large Paftures: and the minute Animalculesnbsp;in a Drop of Water fwim about with asnbsp;much Freedom as Whales do in the Ocean :nbsp;�All have equal Room in Proportion tonbsp;their own Bulk.

The Term or Duration of Life, in different Creatures, is likewife comparatively long or fhort, according to the Number,nbsp;Quicknefs, or Slownefs of Ideas prefentingnbsp;themfelves fuccedively to the Mind. For,nbsp;when the Ideas fucceed one another fwiftly,nbsp;and many of them are crowded into a narrow Cornpafs, the Time, however iliort itnbsp;may be, will feem long in Proportion to thenbsp;Number of Ideas paffing through it; on thenbsp;contrary, when the Ideas are but few, andnbsp;follow one another very flowly, a long Timenbsp;will appear fliort, in Proportion to theirnbsp;flow Succeffion, and the Smallnefs of theirnbsp;Number.

� It is evident, fays Mr. Locke, to any one who will but obferve what paffes innbsp;his own Mind, that there is a Train ofnbsp;� Ideas, which conftantly fucceed one ano-

ther in his Underftanding, as long as hc is awake. Refledtion on thele x\ppear-** ances of feverai Ideas one after another innbsp;�� our Minds, is what we call Duration.

For whilft we are thinking, or whilft we ** rec�ive fucceffively feverai Ideas in ournbsp;** Minds, we know that we do exift ; andnbsp;fo we call the Exiftence, or the Conti-nuation of Exiftence of ourfelves, or anynbsp;Thing elfe commenfurate to the Succeftionnbsp;of any Ideas in our Minds, the Durationnbsp;of ourfelves, or any fuch other Thingnbsp;co-exifting with our Thinking

From thefe Principles it is manifeft, that one Day may appear as a thoufand Years,nbsp;and a thoufand Years but as one Day : bynbsp;which Means, the Lives of all Creatures, fornbsp;aught we know, may feem to themfelvesnbsp;nearly of the fame Duration. It is at leaftnbsp;probable, that fomething like this maynbsp;really be the Cafe as to the Inhabitants ofnbsp;this our Earth : for as the fame Functionsnbsp;or Offices of Life, namely, to be born, feeknbsp;proper Suftenance, increafe in Bulk, arrivenbsp;at full Maturity, propagate the Kind, andnbsp;die, are equally performed by all; they whonbsp;perform them in a few Months, Days, or

Difcoveries made by the Microfcope. 305

Hours *, may be fuppofed, from the Number and fwift Succeffion of Ideas fuited to all thefe Purpofes, to live as long, according to

* Swammerdam has publilhed, in Lo^ Dutch, a curious Account of what he calls ihe Ephemeron �, a Fly which, henbsp;tells us, lives but five Hours. This Infett is found about allnbsp;the Mouths of the Rhine', and, according to his Drawingsnbsp;and Defcriptions, feems to be a Species fomawhat betweennbsp;our May-Fly (bred from the CaJextiWorm) and the Lilella ornbsp;Dragon-Fly, It has four Wings, two whereof are fliorter thannbsp;the other ; a Pair of fmall Horns, fix Legs, and two very longnbsp;firaight Hairs ifluing from the Tail. They are feen, he fays,nbsp;flying near the Surface of the Water, about Midfummer, fornbsp;three fucceeding Days, but no longer in one Seafon. Theynbsp;eat nothing ; and their only Bafinefs is to generate, and dropnbsp;their Eggs upon the Water : which Egg$, finking to the Bottom, produce a Kind of Worms or Maggots, that foon hollownbsp;themfelves Cavities in the Clay, where they abide threenbsp;Years; growing each Year about an Inch in Length. Whennbsp;the Worm is come to its full Growth, it rifes to the Surface,nbsp;about fix o�clock in an Evening ; lays its Eggs, and diesnbsp;about ten o�CIock the fame Night.

I am furprized that Swammerdam fliould fay, the Life of this Creature is no more than five Hours, when his ownnbsp;Account plainly proves that it really lives three Years : fornbsp;it is certainly as much alive in the Worm State, as when afterwards it becomes a Fly.-Truth Ihould be every Body�s

Purfuit; and for the Sake thereof I have endeavoured to dear up the general Miftake as to this Fly, which is frequentlynbsp;produced, upon Swammerdam�s Authority, as the mollnbsp;remarkable Inftance we know of the Shortnefs of Life.�Butnbsp;tho� this Infedl happens to live much longer than was imagined, I make no Doubt, there are fome among the number-lefs Species of Beings, whofe natural Lives are as ihort as thisnbsp;was fuppofed to be ; fuch too are moll likely to be foundnbsp;amongft the very minute Kinds. For as t\to{e exceeding/mailnbsp;Plants, invifible to the naked Eye, which compofe what wenbsp;call Mouldine/s, fprlng up, bear Fruit, and die in a fewnbsp;Hours ; we may realbnably fuppofe the Lives of fome rx-ceedingly /mail Animals to be of as Ihort a Duration.

their

their own thinking, as other Creatures do, where the fame Train of Ideas proceed morenbsp;Ilowly, and take up many Years.

As the Microfcope difcovers almoft every Drop of Water, every Blade of Grafs, everynbsp;Leaf, Flower, and Grain, fwarming with Inhabitants, all of which enjoy not only Lifenbsp;but Flappinefs ; a thinking Mind can fcarcenbsp;forbear coniidering that Part of the Scale ofnbsp;Beings which defcends from himfelf to thenbsp;ioweft of ail fenfitive Creatures, and maynbsp;confequently be brought under his Examination. � Amongft thefe, fome are raifed fonbsp;little above dead Matter, that it is difficult tonbsp;determine whether they live or no others,nbsp;but one Step higher, have no other Senfenbsp;befides Feeling and Tafte : fome, again, havenbsp;the additional one of Hearing, others ofnbsp;Smell, and others of Sight �*.

It is wonderful to obferve, by what a gradual Progreffion the World of Life advances through a prodigious Variety of Species, before a Creature is formed that is complete innbsp;all its Senfes: and, even amongft thefe, therenbsp;is fuch a different Degree of Perfedtion innbsp;the Senfes which one Animal enjoys beyond what appears in another, that tho� thenbsp;Senfe in different Animals be diftinguiffied

by the fame common Denomination, it feems almoft of a different Nature. If, after this,nbsp;we look into the feveral inward Perfedlionsnbsp;of Cunning and Sagacity, or what we generally call Inftind:, we find them rifing in thenbsp;fame Manner, imperceptibly, one abovenbsp;another, and receiving additional Improvements according to the Species in whichnbsp;they are implanted.

This Progrefs in Nature is fo very gradual, that the whole Chafm, from a Plant to anbsp;Man, is filled up with divers Kinds of Creatures, rifing one over another by fuch a gentle and eafyAfcent, that the littleTranfitionsnbsp;and Deviations from one Species to anothernbsp;are almofl infenfible. And the intermediatenbsp;Space is fo well hufbanded and managed,nbsp;that there is fcarce a Degree of Perceptionnbsp;which does not appear in fome one Part ofnbsp;the World of Life. Since then the Scale ofnbsp;Being advances by fuch regular Steps fo highnbsp;as Man, we may by Parity of Reafon fup-pofe, that it ftill proceeds gradually upwardsnbsp;thro� numberlefs Orders of Beings of a fupe-'nbsp;rior Nature to him : as there is an infinitelynbsp;greater Space and Room for different Degreesnbsp;of Perfedlion between the Supreme Beingnbsp;and Man, than between Man and the moflnbsp;defpicable Infedf,�

Mr. Locke�s Thoughts upon this Subjedt are very curious : � That there fliould�, fays

� above ys, than there are of fenfible and � material below us, is probable to me fromnbsp;� hence, that in all the vifible and corporealnbsp;World we fee no Chafm, no Gaps. Allnbsp;� quite down from us thp Defcent is by ea-� fy Steps and a continued Series of Things,nbsp;that in each Remove differ very little onenbsp;� from the other. There are Fifties thatnbsp;have Wings, and are not Strangers to thenbsp;� airyRegionj and there arefome Birds thatnbsp;� are Inhabitants of the Water, whofe Bloodnbsp;� is as cold as Fifties�, and theirTlefti fo likenbsp;� in Tafle, that the Scrupulous are allowednbsp;� them on Fifh-Days. There are Animalsnbsp;� fo near a-kin to Birds and Beafts, thatnbsp;� they are in the Middle between both.nbsp;� Amphibious Animals link the Terreftrialnbsp;� and Aquatic together : Seals live at Seanbsp;� and at Land j and Porpoifes have the warmnbsp;� Blood and Entrails of a Hog : not tonbsp;� mention what is confidently reported ofnbsp;Mermaids or Sea-men.^�There are fomenbsp;� Brutes that feemto have as much Know-ledge and Reafon as fome that are callednbsp;Men ; and the Animal and Vegetablenbsp;Kingdoms are fo nearly joined, that ifnbsp;� you will take the lowed of one and thenbsp;higheft: of the other, there will fcarce benbsp;� perceived any great Difference betweennbsp;them. And fo on till we come to the

loweft and fhe moft inorganical Parts of Matter, we fhall find every where thatnbsp;the feveral Species are linked together, andnbsp;differ but in ahnoft infenfible Degrees.nbsp;And when w�e confider the infinite Powernbsp;and Wifdom of the Maker, we have Rea-fon to think, that it is fuitable to thenbsp;magnificent Harmony of the Univerfe,nbsp;and the great Defign and infinite Goodnefsnbsp;of the Archited:, that the Species of Creatures fhould alfo, by gentle Degrees, af-' cend upwards from us towards his infi-' nite Perfedion j as we fee they graduallynbsp;� defcend from us downwards. \�hich, ifnbsp;it be probable, we have Reafon then tonbsp;' be perfuaded, that there are far moreSpe-' cies of Creatures above us than there arenbsp;' beneath j we being in Degree of Perfec-' tion much more remote from the infinitenbsp;' Being of God, than we are from the lowednbsp;' State of Being, or that which approachesnbsp;' neared to Nothing.�

Every Creature is confined to a certain Meafure of Space, and its Obfervation dintednbsp;to a certain Number of Objeds : but fomenbsp;move and ad in a Sphere of a wider Circumference than that of others, accordingnbsp;as they rife above one another in the Scalenbsp;of Exidence. This Earth is the Spot appointed for Man to dwell and ad upon ; he

{lands foremoil of all the Creatures here, and links together Intelligences and Brutes. Thenbsp;Sphere of his bodily Adtion is limited, confined, and narrow ; but that of his Mind isnbsp;vail, and exteniive beyond the Bounds ofnbsp;Matter. Formed for the Enjoyment of in-telledlual Pleafures, his Happinefs arifes fromnbsp;his Knowledge; and his Knowledge increafesnbsp;in Proportion as he difcovers and contemplates the Variety, Order, Beauty, and Per-fedlion of the Works of Nature: whatever,nbsp;therefore, can affiil him in extending his Ob-fervations is to be valued, as in the famenbsp;Degree conducive to his Happinefs.

What we know at prefent, even of Things the moil near and familiar to us, is fo littlenbsp;in Comparifon of what we know not, thatnbsp;there remains a boundlefs Scope for our Enquiries and Difeoveries; and every Step wenbsp;take, ferves to enlarge our Capacities, andnbsp;give us ilill more noble and juil Ideas ofnbsp;the Power, Wifdom, and Goodnefs of thenbsp;Deity.

The Univerfe is fo full of Wonders, that perhaps Eternity alone can be fufficient tonbsp;furvey and admire them all: perhaps, too,nbsp;this delightful Employment maybe one greatnbsp;Part of the Felicity of the Bleifed.�Whennbsp;the Soul fhall become divefted of Flefh, thenbsp;Pleafures of Senfe can be no more : and if,

by a continued Habit, any Longings after them (hall hang about it, fuch Longings mudnbsp;create a proportionable Degree of Wretched-nefs, as they can never poffibly be gratified.nbsp;But if its principal Delight has been in thenbsp;Contemplation of the Beauties of the Creation, and the Adoration of their Almightynbsp;Author, it foars, when difembodied, intonbsp;the celeftial Regions, duly prepared for thenbsp;full Enjoyment of intelle�ual Happinefs.

To Thee, eternal felf-exifting Creator of the Universe ! whofe Will is Nature�snbsp;Law! Omnifcient,Omniprefent, All-Bountiful, and Gracious ! To Thee be paid, bynbsp;all thy Creatures, Thankfgiving andnbsp;Adoration, till Time (hall be no more 1

INDEX.

anemone (Sea) or Mujhraom, an extraordinary Anl-mal nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;��nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;� Page qq

Eel-like Kinds nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;� jg

obferved in feveral Infufions by Monf. Joblot 87 why not always the fame �nbsp;nbsp;nbsp;nbsp;� ibid,

in itchy Puftules in the Light of Oyfters �nbsp;Animalcules in Semitic Ma/culino, how to view �nbsp;when firft difeovered �nbsp;nbsp;nbsp;nbsp;�

their general Appearance their Numbers computednbsp;th eir wonderful Minutenefsnbsp;Reflexions on their Size

1 N D E X.	311
in Semine Mafeulino of a Frog	� nbsp;nbsp;nbsp;p. 154
of a Cod Fill) .	� nbsp;nbsp;nbsp;IS5
of a Pike nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�	~ nbsp;nbsp;nbsp;158
of a Cock nbsp;nbsp;nbsp;�	� �59
of a Dog nbsp;nbsp;nbsp;�	� nbsp;nbsp;nbsp;160
cfaHare nbsp;nbsp;nbsp;�	� ibid.
of a Rabbet nbsp;nbsp;nbsp;�	� nbsp;nbsp;nbsp;161
of a Ram nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�	� ibid.
of a Man nbsp;nbsp;nbsp;�	~ nbsp;nbsp;nbsp;163
of a Spider nbsp;nbsp;nbsp;�	� nbsp;nbsp;nbsp;165
of a Dormoufe nbsp;nbsp;nbsp;�-	� nbsp;nbsp;nbsp;166
of an Oyfter nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�	166, 239
of the Mufcle Filh nbsp;nbsp;nbsp;�	� 243
of a Silkworm nbsp;nbsp;nbsp;�	166, 282
of a Dragon Fly nbsp;nbsp;nbsp;�	� 166
of a common Fly nbsp;nbsp;nbsp;�	� nbsp;nbsp;nbsp;ibid.
of a Flea nbsp;nbsp;nbsp;��	� nbsp;nbsp;nbsp;ibid.
of a Gnat nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�	�. nbsp;nbsp;nbsp;206

Art compared with Nature _ nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;� 292, 297, 299

merely comparative nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;41,303

Account of as fo examined nbsp;nbsp;nbsp;,�;nbsp;nbsp;nbsp;nbsp;��nbsp;nbsp;nbsp;nbsp;104

Strudure and Compofition of Globules � ibid. Size of the Globulesnbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;��nbsp;nbsp;nbsp;nbsp;105

I N D E X.

INDEX.

Ducknxieed, ftrange Animalcules at its Roots Dungbill-lVater full of Animalcules �nbsp;Dying, the Appearance of the Blood then

	3�5
�	p. 290
�	279
	31.35
	299
�MB	290
	288
	16
�	289
�	24, 48
iM.	91
�	85
quot;	136
�BM	185
	23s
�	122
	238
�	78, 278
�	79
�	80
	81
	82
e	ibid.
�.	284
�	3O�
	ibid.
MB	247
	149,248
	249
	250
	ibid.
��	131,251
	285
--
	J39
	140
�-	141
	279
	'3
	Fijb-

INDEX.

a Grafshopper 5- nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;tbtd.

y 2

INDE

32�

Mojfesi exceedingly beautiful Objefls Motion feen by Microfcopes, how to be regardednbsp;Mouidinefs, feveral Species of Minute Plantsnbsp;Multipes or Scolopendra, very curiousnbsp;Mufcles of the Abdomen of a Frognbsp;Mu/de-FiJh a fine Obje�t

ibid.

, 15S

.AS

thid.

Hid,

how to prepare and apply �to make a Colleftion ofnbsp;Cautions in the viewing ofnbsp;endlefsnbsp;nbsp;nbsp;nbsp;�-nbsp;nbsp;nbsp;nbsp;�

0/lt;/People, their Manner of Sight _ nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;� p. 5

			Magnifies	Magnifies	Magnifies the
			the Dia-	the Super-	Cube of an
			meter.	ficies.	ObjeFi,
	' 1, or	5�^	16	256	4.096'
	A, or	40	20	400	8,000
	As or	3�	26	676	17,576
	T, or	20	40	1,600	64,000
		15	53	2,806	148,877
		14	G 57	3�249	185,193
		13	61	3,721	226,981
		12	� 66	4^356	287,496
The Focus oflt;		11	0 nbsp;nbsp;nbsp;72	5,184	373.248
The Focus oflt;	A, or	10	!�� nbsp;nbsp;nbsp;80	6,400	512,000	^ Times.
a Glafs at		9	- 88	7gt;744	681,472
		8	I oo	10,000	1,000,000
		7		12,996	1,481,544
		6	� 133	17,689	2.352.637
	A, X or 5		'Xi 160	25,600	4,096,000
		4	200	40,000	8,000,000
		3	266	70,756	18,821,096
	A, or	2	400	160,000	64,000,000
		I-	800	640,000	5 I 2,000,000_

2				Magnifies the		Magnifies th
fcT P				Diam.		Superficies
I.'		� 3%, or 2 �	-C	� 400'		- 160,000*
2.		A. or 5	c Hi	� 160		� 25,600
3-	Dlft. of ? the Fo--lt;	8	s U. gt;� � in	� 100	� (O 1 ^ gt;	�10,000 gt;
4-	cus at	16	ki rt	� SO	h	� 2,500

S-		t^.or 30	8	-�26		� 676
		. h or 5� -		--16.		- 256^

Gad Bee: vide Ox-Fly nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�-		207
Generation equivocal, contrary to Reafon	�	148
Manner of nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�	�	ICO
analogous between Animals and Vegetables 151
Glafs fiat, its Efi�� nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�	�	3
convex, its EfFedl nbsp;nbsp;nbsp;�	�	4. 6
-its magnifying Power explained	�	33
how to find its magnifying Power	�	34
concave, its EfFeft nbsp;nbsp;nbsp;�	�	S
Glafs Slips of different Colours, their Ufe	�	60
GlaJ/es mufl be fuited to the Objects	�	53
Glafs-Tube, its Ufe nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;�	�	II, 19
Globules of the Blood how formed nbsp;nbsp;nbsp;�	�	103
their Size nbsp;nbsp;nbsp;�nbsp;nbsp;nbsp;nbsp;��	�	101,132
their Appearance in Sicknefs	�	108
in Fiflies and aquatic Animals	�	131
how affeCled by Heat and Cold	�	ibid.
Vide Circulation.
Globule, or Drop of Glafs, its Inconvenience		6
not ufed by Mr, Leeuaxenhoek	_	7
Gnat, its Manner of Production	68,	88, 207
Defcription of it nbsp;nbsp;nbsp;�	�	203
its Form in the Water nbsp;nbsp;nbsp;~	�	83
its Wings and Horns nbsp;nbsp;nbsp;�		205
its Piercer defcribed nbsp;nbsp;nbsp;�		204
its Spawn nbsp;nbsp;nbsp;�		206
Grain of Sand how to be underitood as a Meafure		41
		Grsivti

MICROSCOPES

DISCOVERIES

By HENRY BAKER,

IN TWO VOLUMES.

LONDON;

Utrechts Univsrs�telts

IVii:s8iiro

MICROSCOPE

I. The Nature, XJfes, and Magnifying PoiverS of the beft Kinds of Microscopesnbsp;Dejcribed, Calculated, and Explained:

Martin Folkes, .E/^;

COUNCIL and FELLOWS

A3 nbsp;nbsp;nbsp;It

DEDICATION. v�

via DEDICATION.

DEDICATION.

Henry Baker,

(xiii)

Contents of the Chapters.

PART the FIRST.

( xvil )

INTRODUCTION.

T:he imROBUCriON. xix

XX �The INTRODUCTION.

The

that

JN^RODUCriON. xxili

THE

MICROSCOPE

CHAP. I.

VoE. I. nbsp;nbsp;nbsp;Bnbsp;nbsp;nbsp;nbsp;When

of

CHAP.

CHAP.

CHAP. ly.

CHAP.

CHAP,

CHAP. VH.

CHAP. VIII.

D 7 nbsp;nbsp;nbsp;See

Ito he placed after Page 36.

truQ

A.

C-

CHAP. XIII.

E 4 nbsp;nbsp;nbsp;it

VoL. J. nbsp;nbsp;nbsp;Fnbsp;nbsp;nbsp;nbsp;the

The

MICROSCOPE;

PART II.

r 67 1

MICROSCOPE

PART 11.

f �8 ]

CHAP. I.

6 nbsp;nbsp;nbsp;As

CHAP. ir.

Pepper �Water.

. .

of

CHAP,

[ 7^ ]

tion.

is

CHAP.

[ 3i ]

CHAP. IV.

is

ji

Animalcules in Waters.

Animalcules in Waters.

once.

.Animalcules in Waters.

H4 nbsp;nbsp;nbsp;He

Animalcules in Waters.

Ammalciiles in Waters.

viviparous.

fix tv

C H A P.

[ 103 3

CHAP.