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By the Council of the Royal Society of London for Improving of Natural Knowledge.
Ordered,72wf tfo Boot written by Robert Hooke,M.^.Fe//o»' of this Society Entitukd, Micrographia, or fome Phyfiological Defcriptions of Minute Bodies, made by Magnifying Glafles, with Obfervations and Inquiries thereupon, Be printed by John Martyn,W James Alleftry, Printers to the faU Society.
Novem. 23.
l66*- Brouncker. P.R.S.
MICROGRAPHIA :
OR SOME
Phyfiologkal Defcriptions
O F
MINUTE BODIES
MADE BY
MAGNIFYING GLASSES-
WITH
Observations and I n clu iries thereupon.
,• . . , III
By Rt HO 0 KE^ Fellow of the Roy a l Society
Non pojjis oculo quantum contendere Linceuf,
Kon tamen idcirco contemnas Lippus inungi. Horat. Ep. lib. I.
LONDO iV^Printed by Jo. MartynSznd Ja. Allcflry, Printers to the Royal Societ Y3and arc to be fold at their Shop at the Bell in £PWs Church-yard. M DC LX V.
TO THE
5rb
KIN
SIR,
3 rl
Do here moft humbly lay this [mall Prefent at Tour Majepes Royal feet. And : though it comes accompa- ny'd with two difadvant ages ,the meannefs of the Author, and of the Subjeft • yet in both I am incouraged by the greatnefs of your Mercy and your Knowledge. By the ozk 1 am taught 0 that you can
A forgive
The Epistle
• forgive the moft prefumptuous 0 fenders : And by the other, that you will not t- fieem the lead work of Nature, or Art, unworthy your Observation. Amidft the many felicities that have accompanied your Majepes happy Reftauration and Government/itis none of the leaft confi- derable, that Fhilofophy and Experimental Lmninghzve profpefd under your Royal Patronage. And as the calm profperity of your Reign has given us ihcleifure to follow thefe Studies of quiet and re- tirement, foit is juft, that the Fruits of them fhould , by way of acknowledge- ment, be return cl to your Majefly. There ares Sir, feveral other of your Subje&s, of your Royal Society, now bufle about Nobler matters : The Im- provement of Manufactures and Agricul- ture, the Jncreafe of Commerce , the Ad- vantage oi ' Navigation: In all which they are a (sifted by your Majepes Incou- rageffient and Example. Amidft all thofe
A greater
Dr D i C ATORY.
greater Defigns0l hereprefume to bring in that which is more proportionable to the finable fs of my Abilities , and to offer fome of the leaft of all vifibk things ,to that Mighty King, that has ejla*. blijhtan Empire over the beft:of all///* vifibk things of this Worlds the Minds of Men.
Tour Majefties mo jl humble
firiT . ttft>\\vV?^ca '^d bruifiiiOD bns Lobwjcn**
and mofi obedient
dtsaf Servant,
^.wolffiita >fb9Sbi!p ->jn wob boiteM HI JOY
\tw4iom z\ 11 10I •.ano'^oiiCI tfLK'; vJ 3:10b **\ aril 1o cAtafcfm oib ogiabnu biuo/i) I JOY
^w-.Vr.*\o( dv,::/- mjoy : ; ; Robert Hooke.
The Preface.
many particulars much outdone by thofeof other Creatures, and when at befi,tobe far Jbort of the perfection they feem capable of: And theft infirmities of the Senfes arife from a double caufe, either from the dif- proportion of the Objed to the Orgzn,whereby an infinite number of things can never enter into them,or elfe from error in the Perception, that many things, which come within their reach, are not received in a right manner.
The like frailties are to be found in the Memory ; we often let many things flip away from us, which deferve to be retain d; and of thofe which we treafure up, a great part it either frivolous or falfe ; and if good, and fubfiantial, either in trail of time obliterated, or at be.fi fo overwhelmed and buried under more frothy notions, that when there it need of them, they are in vain fought for.
The two main foundations being fo deceivable, it is no wonder, that all the fucceeding works which we build upon them,of arguing, conclu- ding,defining,judging, and all the other degrees of Eeafon, are lyable to the fame imperfection, being, at befi, either vain, or uncertain : So that the errors of the underftanding are anfwerable to the two other, being defective both in the quantity andgoodnefs of its knowledge ; for the li- mits, to which our thoughts are confi nd, are fmallin r effect of tfa vafl extent of Nature it felf ; fome parts of it are too large to be comprehen- ded, and fome too little to beperceived. And from thence it muftfol- tow,that not having a full fenfation of the Object, we muft be very lame and imperfect in our conceptions about it, and in alfthe proportions which we build upon it ; hence, we often take the (hadow of things fir the fubftance, fmall appearances for good fimilitudes, fimilitudes for definitions; and even many of thofe, which we think, to be the rnofl folid definitions, are rather expreffions of our ownmifguided apprehen- fions then of the true nature of the things thernfelves. • The effects of thefe imperfections are manifefiedin different ways,ac- cording to the temper and diffofition of the fever al minds of men, fome they incline to grofs ignorance and fiupidity, and others to a pre- fumptuous impofing on other mens Opinions, and a confident dog- matizing on matters, whereof there it no affurance to be given.
The Preface.
Tim all the uncertainty, and miftakes of humane aliions, proceed either from the narrownefs and wandring of our Senfes, from the flippe- rincfl or delufion of our Memory, from the confinement or rajlmejl of <wr Understanding, /<?ffe *ti& no wonder, that our power over natu- ral caufes and effetls it fo flowl) 'vnprovd, feeing we are not only to contend with the obfeurity and difficulty of the things whereon we work, and think J)ut even the for ces of our own minds conffrire to betray uti.
Thcfe being the dangers in the proc-efl of humane Eeafon, the remedies of them all can only proceed from the real, the mechanical, the ex- perimenta! Phihjophy, which has this advantage overthePhilofophyof difcourfe and d\fyuVdt\on,tbat whereas that chiefly aims at the fubtilty of its Deductions and Condufwns , without much rigard to the firfl ground-work , which ought to be well laid on theSenfe and Memory ; fo this intends the right ordering of them all,and the making them fer- viceable to each other.
Thefirft thing to be undertaken in this weighty work., is a watch- fulnefs over the failings and an inlargement of the dominion, of the Smfes.
To which end it is requifite, firfi, That there JIjouU be a fcrupu- lous choice,and a ftrict examination, of the reality, conftancy, and certainty of the Particulars that we ddmit:Thk is the fir ft rife where- on truth is to begin, and here the moft fever andmoft impartial dili- gence, mufi be imployed ; the ftoring up of all, without any regard to evidence or ufe, will only tend to. darknefs and confufion. We mufi not therefore efleem the riches of ourPhilofophicaltreafure by the num- ber only, but chiefly by the weight moft vulgar Inftances are not to be neglet\ed,but above all, the moft inftructive are to be entertain d ; thefootfteps of Nature are to betracd,not only in her ordinary courle, but when fhe feems to be put to her jhifis,to make many doublings and turnings, and to ufe fomekjnd of art in indeavouring to avoid our difcovery.
The next care to be taken, in reffetl of the Senfes, is a fupplying of their infirmities with Infrruments, and, as it were, the adding of arti- ficial Organs to the natural ; this in one of them has been of late years
accom-
The Preface.
accomplifht with prodigious benefit to all forts of ufeful knowledge , by the invention of Optical Glajfes. By the means of Telefcopes, there is nothing fo far diftant but may be represented to our view ; and by the help of Microfcopes, there is nothing fo fmall, as toefcape our inqui- ry ; hence there is a new vifible World difcovered to the underftanding. By this means the Heavens are opend, and a vafl number of new Stars, and new Motions, and new Produtlions appear in them, to which all the antient Aflronomerswere utterly Strangers. By this the Earth it felf, which lyes fo neer us, under our feet, fbews quite a new thing to us, and in every little particle of its matter, we now behold almoft as great a variety of Creatures, as we were able before to reckon up in the whole Univerfe/V felf
It feems not improbable , but that by thefe helps the fubtilty of the compofition of Bodies, the ftrufiure of their parts, the various texture of their matter, the inflruments and manner of their inward motions, and all the other pojfible appearances of things, may come to be more fully difcovered ; all which the antient Peripateticks were content to comprehend in two general and ( unleft further explain d) ufekjl words of Matter and Form.From whence there may arife many admi- rable advantages,towards the increafe of the Operative, and the Me- chanick Knowledge, to which this Age feems fo much inclined, becaufe we may perhaps be inabled todifcern all the fecret workings of Nature, almoft in the fame manner as we do thofe that are the productions of Art, and are rnanagd by Wheels, and Engines, and Springs, that were devifed by humane Wit.
In this kind I here prefent to the World my imperfettlndeavours ; which though they Jb all prove no other way confiderable,yet, I hope, they may be in fome meafure ufeful to the main Defign of a reformation inPhilofophy,if it be only by Jhewing, that there is not fo muchrequifd towards it,any ftrength of Imagination^ exat\nefs of Method,^ depth of Contemplation(*/w/g/> the addition of thefe,where they can be had, muft needs produce a much moreperfetl compofure)as afmcere Hand, and a faithful Eye, to examine, and to record, the things themfelves as they appear.
And
The Preface.
And I beg my Render ; to let me take the boldnefl to affure hint, that in this prefent condition of knowledge , a man fo qualified, as 1 have indeavoured to he, only with refolution, and integrity, and plain intentions of imploying hi* Senfes aright /nay venture to compare the re- alky and the ufefulnefl of hit fervices, towards the true Philofophy, with thofe of other men, that are of much fir onger, and more acute fpecula- tions,tte fl) all not mahz ufe of the fame method by the Senfes.
The truth is, the Science of Nature has been already too long made only a work of the Brain and the Fancy : It is now high time that it fhould return to the plainnefi and (oundnefl of Obfervations on ma- terial and obvious things. It it faid of great Empires, That the beft way to preferve them from decay, is to bring them back to the firft Principles, and Arts, on which they did begin. The fame is undoubtedly true in Philofophy,thatbywandringfar away into invi- fible Notions,/;^ almoft quite deftroyd it felfand it can never be re- covered, or continued, but by returning into the fame fenfible paths, in which it did at firft proceed.
If therefore the Reader expetls from me any infallible Deductions, or certainty of Axioms, I am to fay for my felf, that thofe fironger Works of Wit and Imagination are above my weak Abilities ; or if they had not been fo, I would not have made ufe of them in this pre- fent Subject before me: Whereever he finds that I have ventufd at any fmallConjetlures, at the caufes of the things that I have ob fervid* Ibefeech him to look upon them only as doubtful Problems,^ uncer- tain ghefles, and not as unquefiionable Conclufions, or matters of un- confutable Science-, I have produced nothing here, with intent to bind his underftanding to an implicit confent ; I am fo far from that, that Idefirehim, not abfolutely to rely upon thefe Obfervations of my eyes, if he finds them contraditled by the future Ocular Experiments of fi- ber and impartial Difcoverers.
As for my part, I have obtained my end, if thefe my fmall Labours fball be thought fit to take up fome place in the large ftocktf natural Obfervations, which fo many hands are bufie in providing. If I have contributed the meaneft foundations whereon others may raife nobler
b Super-
The Preface.
Superfrructures, lam abundantly fatisfied ; and all my ambition is, that I may ferve to the great Phibjophers of this Age , a* the makers and the grinders of myGlaffesdidtome ; that I may prepare and fur- nifh them with fome Materials, which they may afterwards order and manage with better skill-, and to far greater advantage.
The next remedies in this univerfal cure of the. Mind are to be. ap- ptyedto the Memory , and they are toconfifi of fuchViretiions a6may inform u*, what things arebefi to be ftor'd up for our purpofe, and which is the beft way of fo difpofing them, that they may not only be kept in fetety, but ready and convenient Jo be at any time produc'd/or ufe, 06 occafion fhall require. But I will not here prevent my felf in what I may fay in another Difcourfe , wherein I fhall make an at- tempt to propofe fome Confederations of the manner of compiling a Na- tural and Artificial Hipry, andoffo ranging and regiftring its Particulars into Philofophical Tables, as may make them mofi ufeful for the raifing cf Axioms and Theories*
The laft indeed h the mofi hazardous Enterprise, and yet the mofi neceflary ; and that it, to takg fuch care that the J udgment and the Reafon of Man ( which is the third Faculty to be repair d and im- proved) jbould receive fuch affifiance, as to avoid the dangers to which it is by nature 'mofi fubjetl. The Irnperfetlions, which I have al- ready mention d, to which it h lyable, do either belong to the extent, or the goodnefs of its knowledge ; and here the difficulty is the grea- ter, leafi that which may be thought a remedy for the one fkodd prove deftru&ive to the other, leafi by feeking to inlarge our Know- ledge, we fkould render it weak, and uncertain ; and leafi by being too fcrupulotis and exatl about every Circumfiance of it, we fboM confine and 'fireighten it too much.
In both thefe the middle wayes are to be taken, nothing kto be omitted, and yet every thing to pafl a mature deliberation .* No Intelligence from Men of all Profeffions, and quarters of the World, to be (\\g\\ted,andyet all to be fo fevereiy examin'd,f^it there rtmam no room for doubt or inftabiUty ; rigour in admitting, f#u$ ftri&hefs in (omparing^nd above all, much flownefs in debating, and
fhynefe
The Prefac e.
{hynefs in determining, it to be prallifed. The Underftanding is to order all the infer iour fer vices of the lower Faculties; but yet h is to do this only -as a lawful Matter, and not as a Tyrant. It muji not in- croach upon their Offices, nor take upon it f elf the employments which belong to either of them. It muftw Atch the irregularities of the Sen- fes, but it muji not go before them, or prevent their hformation. It awa^ekamine, range, and diipofe,o/ the bank, which is laid up in the Memory ; but it muji be fure to mak$ dirrin&ion between the fober and well collected heap , and the extravagant Idea's, and miftaken Images , which there it may fmetimes light upon. So many art the links,7//W2 which the true Phihfopky depends, of whiehftf anyone be loofe, wweak , the whole chain is in danger oj being diffdv d his to be- gin with the Hands and Eyes, and to proceed on through the Memory % to be continued by the Reajbn ; nor is it to pop there, but to corne about to the Hands and Eyes again, and fo, by a continual paffage round from one F acuity to another , it is to be maintained in life andftrength, as much as the body of man is by recirculation of the blood through the fever al farts of the body, the Arms, the Fat, the Lungs, the Heart, and the Head.
If once this method were followed with diligence and attention, there is nothing that lyes within the power of human Wit (or which is far more zffeUual ) of human Induftry , which we might not compafl ; we might not only hope for Inventions to equalize thofe of Copernicus, Galileo, Gilbert Haivy, and of others, whofe Names are almoft loft, that were the Inventors of Gun-powder, tfeSeamans Compafs, Printing, Etching, Graving, Microfcopes, &c. but multitudes that may far exceed them : for even thofe difcoveries feem to have been the producls of fome fuch me- thod, though but imperfeUx ; What may not be therefore expecled from it if thoroughly profecuted? Talking and contention of Arguments would foon be turn d into labours ; all the fine&rezvns of Opinions, and uni- vcrfal metaphyseal natures, which the luxury of fubtil Brains has de- vis d, would quickly vaniff), andgiveplace to iolid fuftories, Experi- ments and Works. And as at firfl, mankind 'fell by tafting of the forbidden Tree of Knowledge,fo we^ their Pofl-erity, may he in 'part reftor'd
The Preface.
by the fame way, not only by beholding and contemplating, but by tu- fting tootbofe fruits of Natural knowledge, that were never jet forbidden.
From hence the World may be ajfified with variety of Inventions, new matter for Sciences may be collected, the old improv'd, and their rufi: rubb d away ; and as it is by the benefit of Senfes that we receive all our Skjll in the works of Nature,fo they alfo may be wonderfully benefited by it, and maybe guided to an eafier and more exail performance of their Offices ; 'tis not unlikely-, hut that we may find out wherein our Senfes arc deficient, and as eafily find wayes of repairing them.
The Indeavours of Skilful men have been mofl converfant about the affijlance of the Eye, and many noble Productions have followed upon it ; and from hence we ma) conclude, that there is a way open d for advancing the operations, not only of all the other Senfes jbut even of the Eye it'felfithat which bat been already done ought not to content m,but rather to incourage U6 to proceed further, and to attempt greater things in the fame and diffe- rent wayes.
'Tis not unlikely, but that there may be yet invented feveral other helps for the eye,as much exceeding thofe already found,asthofe do the bare eye,fuch as by which we may perhaps be able to difcover living Creatures in the Moon, or other Planets, the figures of the compounding Particles of matter, and the particular Schematifms and Textures of Bodies.
And as Glafles have highly promoted our feeing,^ 'tis notimpr (ha- bitant that there may be found many Mechanical Inventions to improve cur other Senfes, of hearing, fmelling, tafting, touching. 'Tis not impoffible to hear awKifyer a furlongs dijlance, it having been already dene; and perhaps the nature of the thing would not make it more im- poffible, though that furlong fijould be ten times multiply d. And though fome famous Authors have affirm d it impoffible to hear through the thin- ned plate of Mufcovy-glafs ; yet Iknow a way, by which 'tis eafie enough to hear one ffeak. through a wall a yard thick. It has not been yet thoroughly examirid,how far Otocoufticons may be improvd, nor what other wayes there may be of quickning our hearing, or conveying found through other bodies then the Air: for that that is not the only medium, / can ajfure the Reader, that I have,by the help of a diftended mre,propa-
gated
The Preface,
anted the found to a very confiderable diflance in an inftant, or with at feemingly quick, a motion at that of lights at leaft, incomparably fwifter then that, which at the fame time was propagated through the Air ; and this not only in a flraight line , or diretl, but in one bended in many angles.
Nor are the other three fo perfet\,but that diligence, attention, and many mechanical contrivances, may alfo highly improve them* For fmce the fenfe of fmelling feems to be made by the fwift paffage of the Air ( impregnated with the fleams and effluvia of fever al odorous Bodies ) through the grijly meanders of the Nofe whofe furfaces are cover'd with a very fenfible nerve , and moiftned ^^tranfuda- tion from the procerus mamillares of the Brain , and fome ad- joyning glandules, and by the moift (team of the Lungs, with a Liquor ■ convenient for the reception of thofe effluvia and by the adhefion and mixing of thofe fleams with that liquor ,and thereby a feeling the nerve, or perhaps by infmuating themfelves into the juices of the brain, after the fame manner, at I have in the following Ob fervations intimated, the parts of Salt topafl through the skins of Efs, and Frogs. Since, I fay, fmelling feems to be made by fome fuch way, 'tit not improbable, but that fome con- trivance, for making a great quantity of Airpajl quicKthrough the Nofe, might at much promote the fenfe of fmelling, at the any wayes hindringthat pafage does dull and deftroy it. Several tryals I have made , both of hindring and promoting this fenfe,and have fucceededin fome according to expectation ; and indeed to me it feems capable of being improvd, for the judging of the conftitutions of many Bodies. Perhaps we may thereby alfo 'fudge ([at other Creatures feem to do) what is wholfome,what poyfon ; and in a word, what are the fpecifick. properties of Bodies.
There may be alfo fome other mechanical wayes found out , of fenfibly perceiving the effluvia of Bodies ; fever al hfiances of which, were it here proper, I could give of Mineral fleams and exhalations ; and it feems not impojfible, but that by fome fuch wayes improved, may be discovered, what Minerals lye buried under the Earth, without the trouble to dig for them ; fome things to confirm thit Conjecture may be found in Agricola, and other Writers of Minerals, fyeaHngof the Vegetables that are apt to thrive, or pine, in thofe fleams, c Whether
The Preface.
Whether alfothofe fleams, which feem to iffue out of the Earth, and tnh with the Air ( and fo to precipitate fome aqueous Exhalations,where- with 't'pi impregnated ) may not be by fome way deteiled before they produce the effetl, feems hard to determine ; yet fomething of thh kind lam able to difcover,by an Inflrument I contrived to fbew all the minute variations in thepreffure of the Air ; by which Iconflantly findjhat before , and during the time of rainy weather ', thepreffure of the Air h lefl, and in dry wea- ther , but efpecially when an Eaftern Wind ( which having pafi over vafi trails of Land it heavy with Earthy ? articles ) blows, it h much more, though thefe changes are varied according to very odd Laws.
The Inftrument is this. I prepare a pretty capaceous Bolt-head A B, with a fmall ftem about two foot and a half long DC; upon the end of this D I put on a fmall bended Glafs,or brazen Syphon D E F ( open at D, E and F, but to be doled with cement at F and E, as occafion ferves) whofe ftem F fhould be about fix or eight inches long, but the bore of it not above half an inch diameter,and very even 5 thefe I fix very ftrongly together by the help of very hard Cement , and then fit the whole Glafs A B C D E F into a long Board3or Frame,in fuch manner3that almoft half the head A B may lye buri- ed in a concave Hemifphere cut into the Board R S $ then I place it fo on the Board RS, as is expreft in the firft Figure of the firft Scheme and fix it very firm and fteady in that pofture, fo as that the weight of the Mercury that is afterwards to be put into it,may not in the leaft fhake or ftir it ; then drawing a line X Y on the F rame R X, fo that it may divide the ball into two equal parts, or that it maypafs, as 'twere, through the center of the ball. 1 begin from that, and divide all the reft of the Board towards LIT into inches, and the inches between the 2 5 and the end E(which need not be above two or three and thirty inches diftant from the line X Y) I fubdivide into Decimals then flopping the end F with foft Cement,or foft Wax, I in- vert the Frame, placing the head downwards, and the Orifice E upwards 5 and by it, with a fmall Funnel, I fill the whole Glafs with Quickfilver then by flopping the fmall Orifice E with my finger, I oftentimes erecr and invert the whole Glafs and Frame,and thereby free the Quickfilver and Glals from all the bubbles or parcels of lurking Air then inverting it as before,Ifill it top full with clear and well ftraind Quickfilver, and having made ready a fmall ball of pretty hard Cement, by heat made very foft, I prels it into the hole E, and thereby flop it very faft and to fecure this Cement from flying out afterward,I bind over it a piece of Leather, that is fpread over in the in- fide with Cement, and wound about it whilft the Cement is hot : Having thus faftned it, 1 gently erect, again the Glafs after this manner : I firft let the Frame down edge-wayes, till the edge R V touch the Floor, or ly horizon- tal 3 and then in that edging pofture raife the end R S 5 this I do , that if there chance to be any Air hidden in the fmall Pipe E, it may alcend into the Pipe F, and not into the Pipe D C : Having thus ere&ed it, and hung it by the hole Q, or fixt it perpendicularly by any other means, I open the end F,
and
The Preface.
and by a fmall Syphon I draw out the Mercury fo long,till I find the furface of it AB in the head to touch exactly the line XY} at which time I immedi- ately take away the Syphon , and if by chance it be run fomewbat below the line X Y, by pouring in gently a little Mercury at F, Iraife it again to its dcfired height , by this contrivance I make all the fenlible rifing and fal- ling of the Mercury to be vifible in the furface of the Mercury in the Pipe F, and fcarceany in the head A B. But becaufe there really is fome fmall change of the upper furface alfo, I find by feveral Obfervations how much it rifes in the Ball, and falls in the Pipe F, to make the diftance between the awo furfaces an inch greater then it was before and the meafure that it falls in the Pipe is the length of the inch by which I am to mark the parts of the Tube F, or the Board on which it lyes, into inches and Decimals : Ha- ving thus juftned and divided it, I have a large Wheel MNOP, whole outmofr limb is divided into two hundred equal parts this by certain fmall Pillars is fixt on the Frame R T, in the manner expreft in the Figure. In the middle of this, on the back fide., in a convenient frame, is placed a fmall Cylinder, whofe circumference is equal to twice the length of one of thofe di vifions, which I find anfwer to an inch of afcent, or defcent, of Mercury : This Cylinder I, is movable on a very fmall Needle 5 on the end of which is fixt a very light Index K L, all which are fo pois'd on the Axis; or Needle, that no part is heavier then another : Then about this Cylinder is wound a fmall Clew of Silk, with two fmall fteel Bullets at each end of it GH; one of thefe, which isfomewhat the heavier, ought to befo big, as freely to move to and fro in the Pipe F 5 by means of which contrivance , every the kaft variation of the height of the Mercury will be made exceeding vifible by the motion to and fro of the fmall Index K L.
But this i* but one way of difcovering the effluvia of the Earth mixt with the Air ; there may be perhaps many others,witnefl the Hygrofcope, an Inftrument whereby the watery fleams volatile in the Air are difcerned, which the Nofe it felfisnot able to find. Thh I have defalk din the following Trail in the Defer iption of the Beard of a wild Oat. Others there are,may be difcovered both by the Nofe , and by other wayes alfo. Thut the fmoak of burning Wood k fmelt, feen, and fufficicntly felt by the eyes: 7he fumes of burning Brimftone are fmelt and difcovered alfo by the deflroying the Colours of Bodies , at by the whitening of a red Rofe : And who knows, but that the Induflry of man, following th'ps me- thod[may find out wayes of improving thh fenfe to 06 great a degree of per- fection 06 it k in any Animal, and perhaps yet higher.
'7# not improbable alfojbut that our tafte may be very much improvd, either by preparing our toft for the Body, as, after eating bitter things, Wine,or other Vinous liquors, are more fenfibly tafled ; or elfe by pre- paring
The Prefacf.
paring Bodies for our taft ; a* the difolving of Metals with acid Liquors, make them taftable, which were before altogether infipid ; thus Lead be- comes Tweeter then Sugar ', and Silver more bitter then Gall, Copper and Iron of mofl loathfome tafts. And indeed the bufinefi of this fenfe being to difcover the pre fence of diffolved Bodies in Liquors put on the Tongue,or in general to difcover that a fluid body has fome folid body dijfolvd in it, and what they are ; whatever contrivance makes this difcovery improves this fenfe* In this kind the mixtures of Chymical Liquors af- ford many Inftances ; as the fweet Vinegar that is impregnated with Lead may be difcovered tobefo by the afufion of a little of an Alcalizate folution : The bitter liquor of Aqua fbrtis and Silver may be difcover d to be chargd with that Metal, by laying in it fome plates of Copper : 'Tis not improbable alfo,but there maybe multitudes of other wayes of difco- vering the parts dijfolvd, or diffoluble in liquors ; and what is this difco- very but a kind of fecundary tafting.
'Tps not improbable alfo,but that the fenfe of feeling may be highly im- provd, for that being a fenfe that judges of the more grofs and robufi: motions of the. Particles of Bodies, feems capable of being improvd and affifted very many wayes. Thus for thediftinguifihing ofUezt and Co\d,the Weather-glafs Thermometer, which I have defcribd in this follow- ing Treatife, do exceedingly perfetl it ; by each of which the leaft varia- tions of heat or cold, which the mofl Acute fenfe is not able to diftinguiff?,are manifefled This is oftentimes further promoted alfo by the help of Burn- ing-glafles,^^ the like^ which colletl and unite the radiating heat. Thus the roughnefs and fmoothnefs of a Body is made much more fenfible by the help of a Microfcope, then by the moft tender and delicate Hand. . Perhaps, a Phyfitian might, by fever al other tangible proprieties , difcover the confiitution of a Body as well as by the Pulfe. I do but infiancein thefe,to fhew what poffibility there may be of many others, and what proba- bility and hopes there were of finding them jf this method .were followed ; for the Offices of the five Senfes being to deteel either the fubtil and curi- ous Motions propagated through all pellucid or perfectly homogeneous Bodies; Or the more grofs and vibrative Puhe communicated through the Air and all other convenient medi ums,whether fluid or folid : Or the
effluvia
The Preface.
effluvia of Bodies diflblv'd in the Air ; Or the particles of bodies dif- lblv'd or diflbluble in Liquors, or the more quick and violent lea- king motion n/heat in all or any of thefe: whatfoever does any my es pro- mate any of thefe kinds of criteria, does aford a way of improving fome one fen fe. And what a multitude of thefe would a diligent Man meet with in hit inquiries ? And this for -the helping and promoting the fenfi- tive faculty only.
Next,as for the Memory, or retentive faculty, we maybe fufficiently infmdted from the written Hiftories of civil actions, what great ajfi- fiance may be afforded the Memory, in the committing to writing things ob- fervable in natural operations. If a Phyfitian be therefore- accounted the more able in his faculty, becaufe he hat had long experience and praclice, the remembrance of which, though perhaps very imperfetl, does regulate all hit after anions : What ought to be thought of that man, that has not only a pefeVi regifter of his own experience,but ps grown old with the experience of many hundreds of years, and many thoufands of men.
And though of late , men, beginning to be fenfible of this convenience, have here and there regiftred and printed fome few Centuries, yet for the mcfipart they are fet down very lamely and imperfeblly, and, I fear, many times not fo truly, they feeming, fever al of them, to be defignd more for Orientation then publique uie : For, not to inflance,that they dofor the moft part, omit thofe Experiences they have made , wherein their Patients have mifcarried,it ps very eafie to beperceiv d,that they do all along hyper- bolically extol their own Prefcriptions, and vilifie thofe of others. Not- withftanding all which, thefe kinds of Hijlories are generally efteernd ufe- ful, even to the ablefi Phyfitian.
What may not be expelled from the rational or deductive Faculty that ps furnifht with fuch Materials, and thofe fo readily adapted, and rang d for ufe,that in a moment, as 'twere, thoufands of Inflances, ferving for the illuftration,determination, or invention, of almoft any inquiry, may be represented even to the fight ? Howneer the nature of Axioms muft all thofe Proportions be which are examind before fo many Wit- nefles ? And how difficult will it be for any, though never fo fubtil an er- ror in Philofophy, to fcape from being difcovefd, after it has indufd the touch, andfo many other tryals ? d What
The Preface.
What kind of mechanical way, andphyfical invention alfo vs there re- quird, that might not this way be found out ? The Invention of a way to find the Longitude of places is eafily perform d, and that to as great per- fection as i&dtftfd\ or to as great an accuratenefs as ^Latitude of places can be found at Sea ; and perhaps yet alfo to a greater certainty then that has been hitherto found, as I pall very ft eedily freely manifefi to the world The way of flying in the Air feems principally unpraclicable, by reafon of the want of ftrength in humane mufcles ; if therefore that could be fuppli d,it were J think? eafie to make twenty contrivances to perform the office of Wings .* What Attempts alfo I have made for the fufplying that Defetl, and my fucceffes therein, which, I think.-, are wholly new, and not inconfiderable, I fball in another place relate,
'Tis not unlikely alfo, but that Chymifts, if they followed this method, might find out their fo much fought for Alkaheft. What an univerfal Menftruum , which difolves all forts of Sulphureous Bodies, I have dif cover d ( which has not been before taken notice of as fuch ) I have ftjewn in the fixteenth Obfervation.
What a prodigious variety of Inventions in Anatomy has this latter Age aforded, even in our own Bodies,in the very Heart, by which we live, andtheBrz\n,which h the feat of our knowledge of other things ? witnefl allthe excellent Works of Pecquet, Bartholinns, Billius, and many others ; and at home, of 'Doclor Ihrvy, Doflor Ent,Do5ior Wil\\s,Doffor Gliflbn. //zCeleftial Obfervations we have far exceeded all theAn- tients,even the Chaldeans and Egyptians themfelves, whofe vaft Plains, high Tov/ers,and clear Air, did not give than fo great advantages over ws, as we have over them by our Giafles. By the help of which, they have been very much outdone by the famous Galileo, Hevelius, Zulichem ; and our own Countrymen, Mr. Rook, Dotlor Wren, and the great Orna- ment of our Church and Nation,the Lord Bifhop of Exeter. And to fay no more in Aerial Difcoveries, there has been a wonderful progrefl made by the Noble Engine of the moft Illuftrious Mr. Boy\e,whom it becomes me to mention with all honour, not only as my particular Patron,but as the Patron of Philofophy it felf ; which he every day increafes by his La- bours, and adorns by hh Example. •
The
The Preface.
The good fuccejl of all theft great Men,and many others, and the nori feemingly great obvioufneis of rnoft of their and divers other Inventions, which from the beginning of the world have been, a* 'twere, trod on, and yet not minded tilltbefe loft inquifitive Ages ( an Argument that there may be yet behind multitudes of the like ) puts me in mind to recommend fuch Stu<iies,and the profecution of them by fuch methods, to the Gentlemen of our Nation jvhofe leifure makes them fit to undertake, and the plenty of their fortunes to accomplifh, extraordinary things in this way. And I do. not onljpropofe this kind of Experimental Philofophy a* a matter of high rapture and delight of the mind, but even as a material and fenfi- ble Pleafure. So vaft is the variety of Gbjefts which will come under their Infyeblions, fo many different wayes there are of handling them, fo great is the fatisfa&ion of finding out new things, that I dare compare the contentment which they will injoy, not only to that of contemplation, but even to that which rnoft men prefer of the very Senfes themfelves.
And if they will pleafe to take any incouragement from fo mean and fo imperfect endeavours as mine, upon my own experience, I can alfure them,without arrogance, That there has not been any inquiry or Pro- blem in Mechanicks, that I have hitherto propounded to my felf, but by a certain method ( which I may on fome other opportunity explain ) I have been able prefently to examine thepoffibility of it ; and iff), as eafily to ex+ cogitate divers wayes of performing it : And indeed it is pojfible to do as much by this method in Mechanicks, as by Algebra can be perform^ in Geometry. Nor can I at all doubt, but that the fame method is as ap- plicable to Phy fical Enquiries , and as likely to find and reap thence as plentiful a crop of Inventions ; and indeed there feems to be no fubjetl fo barrenjbut may with this good husbandry be highly improv d.
Toward the profecution of this method i/zPhyfical Inquiries, J. have here and there gleaned up an handful of Obfervations, in the colletlion of mofi of which I made ufe o/Microfcopes, and fome other Glafles and In- ftruments that improve the fenfe ; which way I have herein taken , not that there are not multitudes of ufeful and pleafant Obfervables,yet uncoU kl\ed,obviom enough without the helps of Art , but only to promote the ufe of Mechanical helps for the Senfes,both in the furveying the already vifible
World,
The P R E F A c t.
World, and for the difcovery of many others hitherto unknown, and to make utjvitb the great Conqueror, to be affefted that we have not yet overcome one World when there are fo many others to be difcovered, every confukrabk improvement ofTelefcopes or Microfcopes^ producing new Worlds and Terra-Incognita's to our view.
The Glajfes lufed were of our English make,but though very good of the kind, yet far port of what might be expebled, could we once find a way of making Glajfes Elliptical, or ofr fome more true fib ape ; for though both Microfcopes, tf/^/Telefcopcs, m they now are, will magnifie an Objecl about a thoufand thoufand times bigger then it appears to the naked eye ; yet the Apertures of the Objecl-glajfes are fo very fmall,that very few Rays an admitted, and even of thofe few there are fo manyfalfe, that the Object appears dark and indiftincl : And indeed thefe inconveniences are fuch,06 feem infepar able from Spherical Glajfes, even when moft exailly made-fout thway we have hitherto made ufe of for thatpurpofe it fo imperfecl,that?jhere may be perhaps ten wrought before one be made tolerably good, and moft of thofe ten perhaps every one differing in goodnefi one from another, which h an Argumentythat the way hitherto ufed i*,at leaft,very uncertain. So that thefe Glajfes have a double def ell , the onefhat very few of them arc exaclly true wrought ; the other, that even of thofe that are befi among them, none will admit a fufficient number of Rayes to magnifie the ObjeSi beyond a determinate bignefi. Againfi which Inconveniences the only Remedies I have hitherto met with are thefe.
Firft, for Microfccpcs ( where the Objecl we view is near and within our power)the befi: way of making it appear bright in the Glafs,is to caft a great quantity of light on it by means of cenvex glajfes.f or thereby ,though the aper- ture be very fmall,yet there will throng in through it fuch multitudes5that an Objecl will by this means indure to be magnifi'd as much again as it would be without it. The way for doing which is this. I make choice of fome Room that has only one window open to the South , and at about three or four foot diftance from this Window,on a Table, I place my Mcrofiope, and then fo place either a round Globe of Water, or a very deep clear piano con- vex Glals ( whofe convex fide is turn'd towards the Window ) that there is a great quantity of Rayes collecled and thrown upon the Objecl; Or if the Sun fhine, I place a (mall piece of oyly Paper very near the Objecl, be- tween that and the light 5 then with a good large Burning-Glafs I lb colled and throw the Rayes on the Paper,that there may be a very great quantity of light pafs through it to the Objecl ~ yet I fo proportion that light, that it
may
The .Preface.
may not Gngc or burn the Paper. Inftead of which Paper there may be made ufe of a fmall piece of Looking-glafs plate , one of whofe fides is made rough by being rubb'd on a Hat Tool with very fine fand, this will, if the heat be leifurely caft on it, indure a much greater degree of heat, and con- fequently very much augment a convenient light. By all which means the light of the Sun, or of a Window, may be fo caft on an Object, as to make it twice as light as it would otherwife be without it, and that without any in- convenience of glaring, which the immediate light of the Sun is very apt to create in moft Objetts 5 for by this means the light isfo equally diffufed, that all parts are alike inlightned } but when the immediate fight of the Sun falls on it, the reflexions from fome few parts are fo vivid, that they drown the appearance of all the other, and are themfel ves alfo, by reafbn of the in- equality of light, indiftindr, and appear only radiant fpots.
Rut becaule the light of the Sun, and alfo that of a Window, is in a conti- nual variation, and fo many Objects cannot be view'd long enough by them to be throughly examin'd 5 befides that , oftentimes the Weather is fo dark and. cloudy, that for many dayes together nothing can be view'd : And be- caufe alfo there are many Objects to be met with in the night, which cannot Co conveniently be kept perhaps till the day, therefore to procure and caft a fufficient quantity of light on an Objeft in the night, I thought of, and often ufed this, Expedient.
Iprocur'd me a fmall Pedeftal , fuch as is defcrib'd in the fifth Figure of the firft Scheme on the fmall Pillar A B, of which were two movable Armes CD, which by means of the Screws E F, I could fix in any part of the Pillar 5 on the undermoft of thele I plac d a pretty large Globe of Glafs G, fill'd with exceeding clear Brine, ftopt, inverted, and fixt in the manner vifible in the Figure $ out of the fide of which Arm proceeded another Arm H, with many joynts $ to the end of which was faftned a deep plain Convex glafs I, which by means of this Arm could be moved to and fro, and fixt in any pofture. On the upper Arm was placed a fmall Lamp K, which could be lo mov'd upon the end of the Arm , as to be fet in a fit pofture to give light through the Ball : By means of this Inftrument duly plac'd , as is expreftinthe Figure, with the (mall flame of a Lamp may be caft as great and convenient a light on the Object as it will well indure^and being always conftant, and to be had at any time, I found moft proper for drawing the reprefentations of thofe fmall Objects I had occafion to obferve.
None of all which ways (though much beyond any other hitherto made ufe of by any I know ) do afford a fufficient help: but after a certain degree of magnifying,they leave us again in the lurch. Hence it were very defirable, that fome way were thought of for making the Objedt-glafs of fuch a Figure as would conveniently bear a large Aperture.
As for Telefcopes, the only improvement they feem capable of i* the increafwg of their length ; for the Objetl being remote, there it no thought of giving it a greater light then it hat ; and therefore to augment the Aperture, the Glafi muji be ground of a very large ff>hete ; for, by that
e means.
The Pre f-a c f.
means,the longer the Glafl be, the bigger aperture will it bear, if the Glafes be of an equal gocdnejl in their kind. Therefore a fix will indure a much larger Aperture then a three foot Glafl ; and a fixtyfoot Glafl mil proportion ably bear a greater Aperture then a thirty ,and mil as much ex- cel it alfo as a fix foot does a three foot? as J have experimentally obfervd in one of that length made by Mr. Richard Reives here at London, which will bear an Aperture above three inches over , and yet make the Objetl proportion ably big and difiincl; whereas there are very few thirty foot Glafes that will indure an Aperture of more then two in- ches over. So that for Telefcopes , fuppofmg we had a very ready way of making their Objetl Glafes of exatlly fiherical Surfaces, we might, by increafing the length of the Glafl, magnifie the Objetl to any ajfignable big- nefl. And for performing both thefe, I cannot imagine any way more ea- fie,and more e^atl, then by this following Enginery means of which, any Glafes,of what length foever,may be fyeedily made.lt feems the moft eafie^ hecaufe with one and the fame Tool may be with care ground an Objetl Glafl, of any length or breadth requisite , and that with very little or no trouble in fitting the Engine , and without much skill in the Grinder. It feems to be the moft exact, for to the very loft flroke the Glafl does regulate and retlifie the Tool to its exatl Figure ; and the longer or more the Tool and Glafl are wrought together, the more exatl will both of them be of the defird Figure. Further, the motions of the Glafl and Tool do fo crofl each other , that there h not one point of either s Surface,but has thoufands of crofi motions thwarting it , fo that there can be no hind of Kings or Gutters made either in the Tool or Glafl.
The contrivance of the Engine is, only to make the ends of two large Mandrils fo to move , that the Centers of them may be at any convenient diftance afunder , and that the Axis of the Mandrils lying both in the fame plain produe'd, may meet each other in any affgnable Angle ; both which requifites may be very well perform'd by the Engine defcrib'd in the third Figure of the firft Scheme : where A B fignirles the Eeam of a Lath fixt per- pendicularly or Horizontally, C D the two Poppet heads, fixt at about two foot diftance, E F an Iron Mandril^whofc tapering neck F runs in an adapt- ed tapering brafs Collar ; the other end E runs or. the point of a Screw G 5 in a convenient place of this is faftned H a pully Wheel, and into the end of it,that comes through the Poppet head C, is fcrc wed a Ring of a hollow Cylinder or fome other conveniently (hap'd Tool, of what widened fhall
be
The Preface.
bs thought moft proper for thecize of Glaflcs , about which it is to be im- ploy'd : As, for Object glafles, between twelve foot and an hundred foot long , the Ring may be about fix inches oyer , or indeed fomcwhat more for thofe longer Glafles. It would be convenient alfo, and not very chargeable, to have four or five fcveral Tools j as one for all Glaflcs between an inch and a foot , one for all Glaflcs between a foot and ten foot long, another for all between ten and an hundred,a fourth for all between a? hundred and a thoufand foot long} and if Ciiriofity fhall ever proceed fo far,one for all lengths between a thoufand and ten thoufand foot long ; for indeed the principle is fuch,that fuppofing the Mandrils well made,andof a good length, and fuppofing great care be ufed in working and poliftiing thcm,I lee no reafonjbut that a Glafs of a thoufand,nay of ten thoufand foot long, may be as well made as one of ten ; for the reafbn is the fame,fuppofing the Mandrils and Tools be made fufficiently ftrong, fo that they cannot bend ; and fuppofing the Glafs., out of which they are wrought, be capable of fo great a regularity in its parts as to refraction : this hollow Cylinder K is to contain the Sand, and by being drove round very quick to and fro by means of a fmall Wheel,which may be mov d with ones foot, ferves to grind theGlafs : The other Mandril isfhap'd like this, but it has an even neckin- ftcad of a taper one,and runs in a Collar, that by the help of a Screw, and a joynt made like M in the Figure, it can be frill adjuftned to the wearing or wafting neck : into the end of this Mandril is fere wed a Chock N, on which with Cement or Glew is faftned the piece of Glafs Q_ that is to be form'd 5 the middle of which Glafs is to be plac'd juft on the edge of the Ring, and the Lath OP is to be fet and fixt ( by means of certain pieces and fcrews, the manner whereof will be fufficiently evidene'd by the Figure ) in fuch an Angle as is requifite to the forming of fuch a Sphere as the Glafs is de- fign'd to be of ', the geometrical ground of which being fufficiently plain, though not heeded before, I fhall, for brevities fake, pais over. This laft ^//Sri/istobemade ( by means of the former, or fome other Wheel) to run round very fwift alfo , by Which two crols motions the GJafs cannot chufe ( if care be us'd ) but be wrought into a moft exa&ly fpherical Surface.
But becaufe tve are certain, from the Laws of refra&ion ( which 1 I have experiment ally found ho he fo,by an Inflrumtnt I fhall prefently dt- fcribe ) that the lines of the angles of Incidence are proportio- nate to the lines of the angles of Refra&ion, therefore if GlaJJes could be made of thofe kind of Figures, or fome other, fuch atthe moft incompa- rable Des Cartes bat invented, and demonftrated in bh Philofopbicaland MathematicalWorks,vee might hope for a much greater perfeclion of Opticks then can be rationally expelled from fpherical ones; for thougb,cxtcr\s pa- ribus, we find, that the larger the Telefcope Objecl Glajfes are, and the fhorter thofe of the Microfcope, the better they magnifie, yet both of them,
befide
The Preface.
bcfidi fuch determinate dimenftons , are by certain inconveniences rendred .unufeful ; for it will be exceeding difficult to make and manage a Tube above an hundred foot long, and it will be at difficult to inlighten an Objetl left then an hundred part of an inch diftant from the Objeft Glaft.
I have not as yet made any attempts of that kind, though I know two or three wayes, which, as far as I have yet considered, feem very probable,and may invite me to mah a tryal as foon as I have an opportunity, of which I may hereafter perhaps acquaint the world. In the Interim, I flialldefcribe the Inftrument I even now mentioned, by which the refra&ion of all kinds of Liquors may be moft exatlly meafurd, thereby to give the curious an opportunity of making what further tryals of that kind they flail think requijite to any of their intended tryals ; and to let them fee that the laws cf Refratlion are not only notional.
The Inftrument confifted of five Rulers , or long pieces placed together, after the manner cxpreft in the fecond Figure of the firft Scheme , where A B denotes a ftraight piece of wood about fix foot and two inches long, about three inches over, and an inch and half thick 5 on the back fide of which was hung a fmall plummet by a line ftretcht from top to bottom, by which this piece was fet exactly upright,and fo very firmly fixt 5 in the mid- dle of this was made a hole or center, into which one end of a hollow cy- lindrical brafeBox CC, fafhion'd as I (hall by and by defcribe, wasplac'd, and could very eafily and truly be mov'd to and fro ; the other end of this Box being put into, and moving in, a hole made in a fmall arm D D ; into this box was faftned the long Ruler E F, about three foot and three or four inches long, and at three foot from the above mention'd Centers P P was a hole E, cut through, and crofs'd with two fmall threads, and at the end of it was fixt a fmall fight G, and on the back fide of it was fixt a fmall Arm H, with a Screw to fix it in any place on the Ruler L M this Ruler L M was mov'd on the Center B (which was exactly three foot diftance from the middle Center P ) and a line drawn through the middle of it LM, was divided by a Line of cords into Ibrne fixty degrees,and each degree was (ub- dividedinto minutes, fothat putting the crofs of the threads in E upon any part of this divided line, I prefently knew what Angle the two Rules A B and E F made with each other, and by turning the Screw in H, I could fix them in any pofition. The other Ruler alio R S was made much after the lame manner, only it was not fixt to the hollow cylindrical Box. but,by means of two fmall brafs Armes or Ears, it mov'd on the Centers of it ; thisalfo, by means of the crofs threads in the holeS, and by a Screw in K, could be faftned on any divifion of another line of cords of the lame radius drawn on N O. And fo by that means, the Angle made by the two Rulers, A B and R S, was alfo known. The Brafs box C C in the middle was (hap d very much like the Figure X, that is, it was a cylindrical Box ftopp'd clofe at ei- ther end,off of which a part both of the fides and bottomes was cut out, fo
that
The Preface.
that the Box, when the Pipe and that was joyne d to it, would contain the Water when till'd half full, and would likewife, without running over, in- dureto beinclind to an Angle 3 equal to that of the gfeateft refraction 6f Water, and no more,without running over. The Ruler E F was fixt very faft to the Pipe V, fb that the PipeV directed the length of the Ruler E F, and the Box and Ruler were mov'd on the Pin TT, fo as to make any defi- rable Angle with the Ruler A B. The bottom of this PipeV wasftop'd with a fmall piece of exactly plain Glafs, which was plac'd exactly per- pendicular to the Line of direction, or Axis of the Ruler £ F. The Pins alio TT weredrill'd with fmall holes through the Axis^and through thofe holes was ftretcht and raltned a fmall Wire. There was likewife a fmall Pipe of Tin loofly pur on upon the end of V, and reaching down to the fight G 5 the ufeof which was only to keep any falfe Rayes of lightfrofn pafling through the bottom of V, and only admitting fuch topafsas pier- ced through the fight G : All things being placed together in the manner defcrib'd in the Figure 5 that is, the Ruler A being flxt perpendicular, t fiirdtheBox CC with Water, or any other Liquor, whofe refraction I in- tended to try , till the Wire palling through the middle of it were juft co- vered : then I moved and fixt the Ruler F E at any aflignablc Angle, and placed the flame of a Candle juft againft the fight G » and looking through the fight I, I moved the Ruler R S to and fro, till I perceived the light pa£ fing through G to be covered, as 'twere, or divided by the dark Wire paf- fingthrough PP.* then turning the Screw i.iK, I fixt it in that pofture: And through the hole S, I obferved what degree and part of it was cut by the crofs threads in S. And this gave me the Angle of Inclination, APS anfweringto the Angle of Refracr.ion BPE : for the furface of the Liquor in the Box will be alwayes horizontal , and confequently A B will be a perpendicular to it 5 the Angle therefore APS will meafure, or be the Angle of Inclination in the Liquor 5 next EPB mult be the Angle of Re- fradion,for the Ray that pafies through the fight G, pafies alio perpendicu- larly through the Glafs Diapl ragmc at F, and confequently alfo perpends cularly through the lower furface of the Liquor contiguous to the Glafs, and therefore fuflers no refraction till it meet with the horizontal furface of the Liquor in C C, which is determined by the two Angles.
By means of this Inftrument I can with\\tt\e trouble, and a very fmall quantity of any Liquor, examine, rnofl accurately, the refra&ion of it , not only for one inclination, but for all-, and thereby am inabled to make very accurate Tables ; fever al of which I have alfo experimentally made,and find, that Oyl of Turpentine has a much greater Refratlion then Spirit of Wine , though it be lighter ; and that Spirit of Wine ha* a greater Refratlion then Water, though it be lighter alfo ; but that fait Water alfo has a greater Refratlion then frefh, though it be heavier : but Allum water has a left refratlion then common Water, though hea- vier alfo.So that it feems,as to the refraction made in a Liquor, the fpeci-
The Preface.
fick gravity U of no efficacy. By this I have alfofoundjhatlookwhat pro- portion the Sine of the Angle of ^Inclination has to the Sine of the Angle of Refraction, correspondent to it^ the fame, proportion have all the Sines of other Inclinations to the Sines of their appropriate Refraftions.
My way for raeafuring how much a date magnifies an Ob ject., plac'd at a convenient diftance from my eye,is this. Having rectifi'd the Microfcope^ to fee the defir'd Object through it very diftinctly, at the fame time that I look upon the Object through the Glafs with one eye, I look upon other Objects at the fame diftance with my other bare eye 5 by which means I am able, by the help of a Ruler divided into inches and fmall parts, and laid on the Pedejial of the Microfcop e,to caft,as it were, the magnifi'd appearance of the Object upon theRuler,and thereby exactly to meafure the Diameter it ap- pears of through the Glafs, which being compar'd with the Diameter it ap- pears of to the naked eye , will eafily afford the quantity of its magnify- ing.
The Microfcope^ which for the moft part I made ufe of, was fhap'd much like that in the lixth Figure of the firft Scheme^ the Tube b.eing for the molt part not above fix or feven inches long,though, by reafon it had four Draw- ers, it could very much be lengthened, as occafion required 5 this was con- trived with three Glaflesja fmall Object Glafs at A, a thinner Eye Glafs about B, and a very deep one about C : this I made ufe of only when I had oc- cafion to fee much of an Object at once 5 the middle Glafs conveying a very great company of radiating Pencils, which would go another way, and throwing them upon the deep Eye Glafs. Rut when ever I had occafion to examine the fmall parts of a Body more accurately , I took out the middle Glafs,and only made ufe of one Eye Glafs with the Object Glafs, for always the fewer the Refractions are, the more bright and clear the Object appears. And therefore 'tis not to be doubted , but could we make a Microfcope to have one only refraction, it would, ceteris paribus , far excel any other that had a greater number. And hence it is, that if you take a very clear piece of a broken Venice Glafs, and in a Lamp draw it out into very fmall hairs or threads, then holding the ends of thefe threads in the flame, till they melt and run into a fmall round Globnl, or drop, which will hang at the end of the thread ; and if further you ftick feveral of thefe upon the end of a flick with a little fealing Wax, fo as that the threads frand upwards, and then on a Whetftone firft grind off a good part of them, and afterward on a fmooth Metal plate, with a little Tripoly, rub them till they come to be very fmooth} if one of thefe befixt with a little foft Wax againft a fmall needle hole,prick'd through a thin Plate of Brafs, Lead, Pewter, or any other Me- tal, and an Object, plac'd very near^ be lock'd at through it, it will both rcagnifie and make fome Objects more diftinct then any of the great Alicro- fecpes. But becaufe thefe, though exceeding eafily made, are yet very trou- bkfometo be us'd,becaufeof their fmalnefs,and the nearnefsof the Object 5 therefore to prevent both thefe, and yet ha ve only two Refractions, I pro- vided me a Tube of Brafs, fhap'd much like that in the fourth Figure of the firft Scheme 3 into thefmaller end of this I fixt with Wax a good piano con- vex
The Preface.
vex Object Glafs,with the convex fide towards the Object, and into the bigger end I fixt alio with wax a pretty large piano Convex Glals, with the convex fide towards my eye, then by means of the fmall hole by the fide 5 I fill'd the intermediate fpace between thefe two Glaflbs with very clear Water, and with a Screw ffapp'd ;itin 5 then putting, on a Cell for the Eye, I could per ceive an Object more bright then I could when the intermediate fpace was only fill'd with Aii^but this, for other in->' conveniences, I made but little ufe of.
My way for fixing both the Glafs and Object to the Pedeftal ruoft conve- niently was thus : Upon one fide of a round Pedeftal A B, in the fixth Fi- gure of the firlt SckemcjNus fixt a fmall Pillar CC, on this was fitted a fmall Iron Arm D, which could be mov'd up and down5and fixt in any part of the Pillar,by means of a fmall Screw E ; on the end of this Arm was a fmall Ball fitted into a kind of focket F,made in the fide of the Brafsrving G, through which the fmall end of the Tube wasfcrew'df, by means of which contri- vance I could place and fix the Tube in what pofture I d efir'd ( which for many Obfervations was exceeding neceftary T and adjuften it molt exactly to any Object.
For placing the Object,! made this contrivance } upon the end of a fmall brafs Link or Staple H H, I lofaftneda round. Plate I I, that it might be turn'd round upon its Center K, and going pretty ftiff, would ftand fixt in any pofture it wasfet § on the fide of this was fixt a, fmall Pillar P, about three quarters of an inch high, and through the top of this was thruft a fmall Iron pin M, whofetop juft flood oyer the Center of the Plate ; on this top I fixt a fmall Object, and by means of thefe contrivances I was able to turn it into all kind of pofitions, both to my Eye and the Light £ for by moving round the fmall Plate on its center, I could move it one way, and by turning the Pin M, I couJdmove it another way , and this without ftirring' the Glals at all , or at leaft but very little : the Plate likewife I could move to and fro to any part of the Pedeftal ( which in -many cafes was very con- venient ) and fix italfb in any Pofition, by means of a Nut N, 'which was fcrew'd on upon the lower part of the Pillar C C All the other Con- trivances are obvious enough from the draught,and will need nodefcription
Now though th'pi were the Inftrument I made rnofi ufe of, yet I have made fever al other Try ah with other kinds of Microfcopes, which both for matter and form were very different from common fyherical Glaffes. I have made a Microfcope with one piece of Glafl, both whofe furfaees were plains. / have made another only with a piano concave, without any kind of reflection, divers alfo by means of reflection. I have made, others of Waters, Gums, Refins, Salts, Arfenick, Oyls, and with divers other mixtures of watery and oyly Liquors. And indeed the fubjetl u capable of a great variety ; but I find generally none more ufe- ful then that which h made with two Glaffes, fuch a* I have already de- fcr&d. What
The Preface.
W hat the things are Iobfervd, the following defer iptions mil mahifefi ; in brief they were either exceeding fmall Bodies, or exceeding fmall Pores, or exceeding fmall Motions, fome of each of which the Reader will find in the following Notes,and fuch, as Iprefume, ( many of them at leafl) will be new, and perhaps not left ftrange: Some fpecimen of each of which Heads the Header will find in the fubfequent delineations, and indeed of fome more then I was willing there Jhould be; which was occafioned by my firfi Intentions to print a much greater number then t have fince found time to compleat. Of fuch therefore as I had, I [elect- ed only fome few of every Head, which for fome particulars feerndmoft ob- servable, rebelling the reft as fuperfluows to the prefent Defign.
What each of the delineated Subjects are,the following defcriptions an- nexe to each will inform,of which I fh all here, only once for all, add, That in divers of them the Gravers have pretty well followed my diretlions and draughts ; and that in making of them, lindeavoured (as far as I was able ) fir ft to difcover the true appearance , and next to makg a plain re- prefentation of it. This I mention the rather , becaufe of thefe kind of Objetls there is much more difficulty to difcover the true ffjape, then of thofe vifible to the naked eye, the fame ObjeM feeming quite differing, in one pofition to the Light, from what it really is, and may be difcover d in another. And therefore I never began to make any draught before by many examinations in fever al lights, and in fever al pofttions to thofe lights, I had difcovefd the true form. For it is exceeding difficult in fome Objetls , to diftinguifh between a prominency and a depreflion, between a fhadow and a black (lain, or a reflection and a whitenefs in the colour. Befides, the transparency of moft Objetls renders them, yet much more difficult then if they were opacous. The Eyes of a Fly in one kind of light appear almoft like a Lattice, drilld through with abun- dance of fmall holes ; which probably may be the Reafon, why the Ingeni- ous Dr. Power feems to fuppofe them fuch. In the Sunfinne they look, like a Surface covefd with golden Nails ; in another pofture,like a Sur- face cover d with Pyramids ; in another with Cones ; and in other po- ftures of quite other fiapes ; but that which exhibits thebeft, is the Light colletled on the Objetl, by thofe means I have already defcribd.
And
. . The PKEFACf. And thh was undertaken in profecut'ion of the Defign which the ROY- AL SOCIETY has proposed to it flelfl. For the Members of the Affembly ha- ving before their eys fo many fatal Inflames of the errors and falfboodsjn which the greatefl part of mankind has fo long wandred, becaufe they relyd upon the flrength of humane Eeaflon alone, have begun anew to correct all Hy- pothefes by flenfle, 06 Seamen do their dead Reckonings by Cceleftial Obfervations;tf7ft/ to thkpurpofe it has been their principal indeavour to en- large is? ftrengthen ffoSenfes by Medicine,^ by fuch outward Inftru- ments a* are proper for their particular works'. By this means they find fome reafbn to fluff etl,that thofle effetls of Bodies ,which have been commonly attri- buted to Qualities, and thofle conflejl'd to be occult, are performed by the flmall Machines of "Nature, which are not to be difcernd without thefle helps^ fleeming themcerprodulls o/Motion,Figure,W Magnitude; and that the Natural Textures, which fome call the Plaftick faculty, may be made in Looms,which a greater perfletlion of Opticks may make diflcernable by theft Glafesflo at new they are no more puzzled about themjhen the vulgar are to conceive, howl 2.^t^vy or fiowred Stuffs are woven. And the ends of all thefle Inquiries they intend to be the Pleafure of Contemplative minds, but above all,the eafe and difpatch of the labours- of mens hands .They do indeed neg- letl no opportunity to bring all the rare things of Remote Countries within the compajl of their knowledge and pr alike. But they flill acknowledg their mod ufeful Informations to arifefrom common things, and from diverfifying their moft ordinary operations upon them. They do not wholly rejetl Experi- ments of meer light and theory ; but they principally aim at fuch, whoflc Applications will improve and facilitate the preflent way 0/ Manual Arts. And though fome men, who are perhaps taken up about lefli honourable Em- ployments, arepleas d to cenfure their proceedings, yet they can flhewmort fruits of their firfl three years, wherein the) haveafflembled, then any other Society in Europe can for a much larger ffaceof time. Tit true, fluch un- dertakings 06 theirs do commonly meet with flmall incouragement, becaufli men are generally rather taken with the pla'ufible and difciirlive, then the, real and the flolidpart of Philoflophy ; yet by the good fortune of their infiitu- tionjnan Age of allothers the moft inquifitive,^ have been affifted by the contribution and^xtknctof very many of the chief 'Nobility and 'Gentry,*
g and
The P R E F A C E.
and other s^ho are foifie of the mod confiderable in their fever al Profeffions. But that that yet farther convinces me of the Real eftcem that the more fe- rious part of men have of thfa Society that fever al Merchants//?^ whd alii in earrtefl(whofe Object fa meum & tuum ,that great Rudder of humane dffairs)have adventufd confiderable fums of Money Jo put in practice what fotrte of our Members have contrived, and have continued ftedfaft in theit good opinions of fuch tndeavours, when not one of a hundred of the vulgar have believed their undertakings feaf able. And it fa alfofit to beaddeJ,that they have one advantage peculiar to themfelves,that very many of their num- ber are men of Conveffe and Traffick ; which fa a good Omen, that their attempts will bring Philofophy from words toz&\on,feeingtbe men ofBufi- nejlhave had fo great a pare in their firfi foundation. And of thfa kind I ought not to conceal one particularGcnerotity, which more nearly concerns my felf.lt fa the munificence of Sir JohnCutler,/« endowing a Letlure for the promotion of Mechanick Arts,to be governed and diretled byThfaSoc'iety JhfaBounty I mention for the Honourablenefs of the thing it felf^andfor the expectation which I have of the efficacy of the Example ;fbr it cannot now be objected to them,that their Vefigns will be efleemed frivolous and vain, when they have fuch a real Teftimony of the Approbation of a Man that fa fuch an eminent Ornament of thfa renowned City, and one-, who, by the Variety, and the happy Succefs, of hfa negotiations, has given evident proofs, that he fa not eafie to be deceived. Thfa Gentleman has well obfervd, that the Arts of life have been too long imprifon d in the dark Jhops of Mechanic^ themfelves,isf there hiridred from gtbwt\\ehher by ig* norance,or felf-interefi\and he hat bravely freed them from thefe inconveni- ences:^ hath not only obliged Tradelmeri^J Trade/* felfHehas done a work that fa Worthy of London, and has taught the chief City of Commerce in the world the right way how Commerce fa to be improvd. We have already feen many other great figns of Liberality and a large mind, from the1 fame hand:For by hfa diligence about ^Corporation for the Poor;^ hfa bono* rabk Subfcriptions/or the rebuilding of &.Paul's;fy hfa chearful Disboirf- ment for the replanting oflrthnd^and by many other fuch publick works, he has Jhewn by what means he indeavours to eftablifli hfa Memory ; and no® by thfa Idftgift he has done that,wUch became one of the wifeft ©Itteefts^
of
The P r £ f a c e.
of our Nation to accompli ft), feeing one of the wifeft of our Statefmen,the Lord Verulam, fix ft propounded it.
But to return to my Subjetl^from a digreffton, which, Ihope,my Reader WH pardon me, feeing the Example is fo rare that lean make no more fucb digreffions. Iftbefe my firft Labours ft) all be any wayes ufefulto inquU ring men, Imuft attribute the incouragement and promotion of them to a ve- ry Reverend and Learned ?eiibn,of wborn this ought in juflice to be faid, That there is fcarce any one invention, which this Nation has pro- diicd in our Age, but it has fome way or other bceri fet forward by his afliftance. My Reader J btlitve,will quickly ghefi, that it is Dr. Wil- kins thatlmean.He id indeed a man born for the good of mankind, and for the honour of 1m Couutry . In the Iweetneis of whofe behaviour,*;? the calmnefs of 1m mind, in the unbounded goodnefs of his heart, we have an evident Inftance, what the true and the primitive unpaffionate Religi- on was, before it Vat fowred by particular Factions. In a word, his Zeal has been fo conftant and effectual in advancing all good and profitable Am,that motie of theAntient Romans {aid ofScipio, That he thanked God that he was a Roman ; becaufe whereever Scipio had been born, there had been the feat of the Empire of the world i So may I thank God, that Dr. Wilkins was an Englishman, for whereever he had lived, there had been the chief Seat of generous Knowledge and true Philofo- phy. fo the truth of tbtefhere are fo many worthy men living that willfub^ fcribe, that I am confident-, what I have here [aid, will not be looked upon, by any ingenious Reader, fa A fenegyrick*, but only as a real tefti-
By the Advice of this Excellent rilan I firft fet upon thti Enterprife,y*t ftill came to it tilth much RelUdLzhcyJbecaufe I was to follow the footftepsof fo eminent a Perfon as Dr. Wren , whotoastbe firft that attempted any thing of this nature \ whofe original draughts do now mak^mhf the Orna- ments of that great ColleUxion of Rarities in the Kings Clofet. This Ho- nor, which bis firft beginnings of this kind have receivd, to be admitted in- to the moft famousplace of the world,didnot fo much incourage, as the ha- zard of coming after Dr. Wren did affright me 5 for of him Imuft affirm^ thdt, fence the time of Archimedes, there fcarce ever met in one man, in fo
great
The P R E F A C E. great a perfection, fitch a Mechanical Hand, and fo Philofophical a Mind.
But at laft,bcing a[fur eel both by Dr. Wilkinsyiwi Dr. Wren himfelf that he had given over hi* intentions of profecuting it, and not finding that there was any elfe defignd thepurfuing of it,Ifet upon this undertaking, and was not a little incouragd to proceed in it,bythe Honour the Royal Society was pleas d to favour me with fin approving of thofe draughts (which from time to time as I had an opportunity of defcribing) Iprefented to them. And particularly by the Incitements of divers of thofe Noble and excellent Per- fons of it, which were my more effecial Friends,who were not left urgent with me for the publi (Jnng, then for the profecution of them.
After I had almoft compleated thefe Pitlum and Obfervations ( ha- ving had divers of them ingraven , and was ready to fend them to the Prefix 1 was inform 'd , that the Ingenious Phyfitian Dr. Henry Power had made fever al Microfcopical Obfervaiions,which had I not afterwards, upon our inter changably viewing each others Pape¥s, found that they were for the mofl part differing from mine, either in the Subject it felf, or in the particulars taken notice of ; and that his defign was only to print Obfer- vations without Pictures,! had even then fupprefled what I had fo far pro-' ceeded in. But being further excited by fever al of my Friends, in comply- ancewith their opinions, that it would, not be unacceptable to fever alinqui- fitive Men, and hoping alfo , that I Jhould thereby difcover fomething New to the World, I have at length caft in my Mite, into- the vafl Treafu- ry of A Philofophical Hiftory . And it k my hope, as well as belief, thai thefe my Labours will be no more comparable to the Productions of many other Natural Philofophers, who are now every where bufie about greater things ; then my little Objects are to be compafd to the greater and more beautifulWorks of Nature, A Flea, a Mite, a Gnaty to an Horfe,an Ele- phant, or a Lyon* ; V\lV;^ ~oH t\K .|!oD jjn'A&i & iM%>a>\\^ ~&s#ttWu w>t .V> d m\ mA W# **A*^i;£;,Vvu\$A itaj vA A^fat'iotf ~:rl sAt it pgjrjijo G\fcv< \ k^sfom vin> $itj^i«rat^ %AvaAt*t
r-..% #\\ :-,\ \>Mjtl£iit\z^R$\W ,iG^{\a^\\\\^\| bigs
SOME
H 4
MICROGRAPH1A,
Phyfiolbgical Dcfcriptians
dbjibnini •.. n.r. P . ru'wK -^.i; i -uf^'r . :. G quifil ?.A /.<;: I
MINUTE BODIES*
in *io •^••UM'!VMADE BY ..v...v.^ {?!ff:'
MAGNIFYING GLASSES;
v :y.\.k j.'-. •.. \\\\.;.'7). • WITH .-I ..-on ' m(»mb
Observations and Inquiries thereupon.
- i ■
Obferv. I. Of the Point of a fbarp fmallNeedk*
fS in Geometry, the moft natural way of* beginning is Schem.2a from a Mathematical jwztf } fo is the fame method in Fig.i» Obfervations and Natural hijiory the moft gcnuinc,fim- p]e, and inftru&ive. We muft firft endevour to make letters j and draw ftngle ftrokes true , before we ven* ture to write whole Sentences y or to draw large Pi* ftures. And in Phyfical Enquiries, we muft endevour to follow Nature in the more plain and eajie ways ihe treads in the moft (imple and uncompounded bodies, to trace her fteps, and be acquainted with her manner of walking there, before we venture our felves into the multitude of meanders {hehas'm bodies of a more complica* ted nature ^ left, being unable todiftinguifh and judge of our way, we quickly lofe both Nature our Guide,and our felves txxxand are left to wan- der in the labyrinth of groundlefs opinions, wanting both judgment^ that lights and experience, that clew, which Ihould direcl: our proceedings.
We will begin thefeour Inquiries therefore with the Obfervations of Bodies of the moft fimple nature firft,and fo gradually proceed to thole of a more compounded one.ln profecution of which method, we ihall begin with a Phyjtcal pointy of which kind the Point of a Needle is commonly reckon'd for one^ and is indeed^ for the moft part, made fo {harp, that the naked eye canuot diftinguifh any parts of it : It very eafily pierces, and makes its way through all kind of bodies fofter then it felf:But if view'd with a very good Mi cr of ope, we may find that the top of a Needle (though as to the
B fenfe
\
MlCROGRAPHIA.
fenfe very Jl)arp) appears a lroad,blunt, and very irregular end } not relem- bjing a Cone, as is imagin'd, but onely a piece of a tapering body, with a great part of the top remov'd, or deficient. The Points of Pins are yet more blunt, and the Points of the moft curious Mathematital Inftruments do very feldome arrive at (o great a lharpnefs how much therefore can be built upon demonstrations made onely by the productions of the Ru- ler and Compalles, he will be better able to coniider that fhall but view thofe points and lines with a Mtcrofcope.
Now though this point be commonly accounted the lharpeft (whence when we would exprels the ftlarptiefs of a point the moft fupcrlatruely, we lay, As (harp as a Needle) yet the Microfcope can afford us hundreds of In- ftances of Points many thoufand times fharper : liich as thole of the hairs, and brijlfes, and claws of multitudes of Inje&s 3 the thorns, or crooks ^ or hairs of haves, and other Imall vegetables 5 nay, the ends of the jiirie or (mall parallelepipeds of Amianthus , and alumen plumojum 5 of many of which, though the Points are lb fharp as not to be vilible, though view'd with a Microjcope (which magnifies the Object, in bulk, above a million of times) yet I doubt not, but were we able pra&ically to make Microfcopes according to the theory of them, we might find hills, and dales,and pores, » and a fufficient bredth, or expanlion, to give all thofe parts elbow-roorri, even in the blunt top of the very Point ot any of thefe lb very ftiarp bodies. For certainly the quantity or extenlion of any body may be Divisible in in- finitum , though perhaps not the matter.
But to proceed : The Image we have here exhibited in the firft Figure, was the top of a Imall and very Ibarp Needle, whole point a a neverthelefs appear'd through the Microfcope above a quarter of an inch broad, not round nor flat , but irregular and un- even^ lb that it feem'd to have been big enough to have afforded a hundred armed Mites room enough to be rang'd by each other without endangering the breaking one anothers necks, by being thruft off Ori ei- ther fide. The furface of which; though appearing to the naked eye very imooth,could not neverthelefs hide a multitude of holes and fcratchesand ruggednefles from being difcover d by the Microfcope to inveft it, feveral of which inequalities (as A,B,C, feem'd holes made by fome fmall Ipecks of Ruji 3 and D lbme adventitious body, that ftuck very dole to it) were ca- fual. All the reft that roughen the furface, were onely fo many marks of the rudenels and bungling of Art. So unaccurate is it, in all its producti- ons, even in thole which leem moft neat, that if examine! with an organ more acute then that by which they were made, the more we fee of their Jhap e, the lels appearance will there be of their beauty : whereas in the works of Nature, the deepeft Difccveries fhew us the greateft Excellen- cies. An evident Argument, that he that was the Author of ah thefe things, was no other then Omnipotent -0 being able to include as great a va- riety of parts and contrivances in the yet lmalleft Dilcernable Poir t, as in thofe vafter bodies (which comparatively are called alio Points) fuch as the Earth, Sun, or Planets. Nor need it feem ftrange that the Earth it felf may be by anAnalogie call'd a^Phyfical Point;For as its body5though now
MlCROGRAPHlA. 3
fo near us as to fill our eys and fancies with a fenfcof the vaftncls of it, may by a little Diftancc, and fome convenient Diminijhing Glaflcs, be made vanifli into a fcarce vilible Speck, or Point (as I have often try'd on the Moon, and (when not too bright) on the Sun it felf.) So, could a Mechanical contrivance fuccesfully anfwerour Theory, we might fee the leaft fpot as big as the Earth it felf 5 and Difcaver, as Des Cartes Dief ch. alio conjectures, as great a variety of bodies in the Mddn^ or Planets, as in l0- § 9- the Earth.
But leaving thefe Diicoveries to future Induftries, we fhall proceed to add one Obfervation more of a point commonly fo caird,that is, the mark of a/w# flop, or period. And for this purpofe Iobferved many bothprinted ones and written 5 and among multitudes I found/hp of them more round or regular then this which I have delineated in the third figure of the fe- cond Scheme, but very many abundantly more disfigurdi, and for the molt part if they leem'd equally round to the eye, I found thole points that had been made by a Copperplate, and Roll-prels, to be as misfnapen as thofe which had been made with Types, the moft curious and Imothly engraven Jirokes and points, looking but as fo many furrows and holes, and their printed imprejjions, but like Jmutty daubings on a matt or uneven floor with a blunt extinguilht brand or (tick's end. And as for points made with a pen they were much more rugged and deformed. Nay,havlng view'd certain pieces of exceeding curious writing of the kind ( one oi which in the bredth of a two-pence eompris'd the Lords prayer, the Apojlles Creed, the ten Commandments, and about half a dozen verfes bejides of the Bible, whole lines were lb fmall and near together, that I was unable to number them with my naked eye, a very ordinary Microfcope, I had then a- bout me, inabled me to fee that what the Writer of it had aflerted was true, but withall dilcover'd of what pitifull bungling fcribbles and fcrdwls it was compos'd,Arabian and China characters being almoft as well fhap'd } yet thus much I mult fay for the Man, that it was for the moft part legible enough, though in Ibrne places there wanted a good fantjy well prepojeji to help one through. If this manner of fmall writing were made eafie and pr amicable ( and I think I know fuch a one, but have never yet made tryal of it, whereby one might be inabled to write a great deale with much eaje, and accurately enough in a very little roome ) it might be of very good ule to convey fecret Intelligence without any danger of Difcovery or mijirujiing. But to come again to the point. The Irregularities of it are caufed by three or four coadjutors, one of which is3 the uneven furfacc of the paper, which at beft appears no Imotherthen a very courle piece of Jhagd cloth; next the irregularity of the Type or Ingraving0 and a third is the rough Daubing of the Printing~Inl{that lies upon the inftrument that makes the impreffion , to all which, add the variation made by the Different lights and fiadows, and you may have lufficient reafon to ghefs that a point may appear much more ugly then this, which I have here prefented, which though it appear 'd through the Microfcope gray, like a great fplatch of London dirt, about three inches over yet to the naked eye it wasblack, and no bigger then that in the midft of the Circle A. And could I have
found
4 MlCROGRAPHIA.
found Room in this Plate to have inferted an O you fhould have feen that the letters were not more diftinft then the points of Diftin&ion, nor a drawn circle more exactly fojhen we have now fhown a point to be a point.
Obferv. I L 0/ ffo £^ 0/ a Razor.
Schtm.i. *' | He fharpeft f^ehath the fame kind of affinity to the fharpeft Pw'»/ Fig. 2. J in Phyficks, as a hath to a point in Mathematicks 5 and therefore the Treaty concerning this, may very properly be annexed to the for- mer. A Razor doth appear to be a Body of a very neat and curious a- fpedt, till more clofcly viewed by the Microfiope^ and there we may ob- ferve its very Edge to be of all kind of fhapes, except what it fhould be. For examining that of a very fharp one, I could not find that any part of it had any thing of fharpnels in it 5 but it appear'd a rough furface of a very confiderable bredth from fide to fide, the narrowed part not feem- ing thinner then the back of a pretty thick Knife. Nor is't likely that it fhould appear any otherwife, fince as we juft now fhew'd that a point ap- peared a circle, 'tis rational a line fhould be a parallelogram.
Now for the drawing this fecond Figure(which reprefentsa part of the Edge about half a quarter of an inch long of a Razor well fet) I fb plac'd it between the Ob jccl-glafs 8c the light.that there appear'd a reflection from the very Edge,repreiented by the white line a b c def. In which you may perceive it to be fomewhat fharper then elfewhere about d0 to be indent- ed or pitted about />, to be broader and thicker about c, and unequal and rugged about e, and pretty even between a b and e f. Nor was that part of the Edge g h i 4 fb fmooth as one would imagine fo fmooth bo- dies as a Hone and Oyl fhould leave it 5 for befides thofe multitudes of fcratchesj, which appear to have raz'd the furface gh i and to crois each other every way which are not half of them expreft in the Figure, there were feveral great and deep fcratches, or furrows, fuch as g h and i 4, which made the furface yet more rugged, caus'd perhaps by fbme fmall Duft cafually falling on the Hone, or fbme harder or more flinty part of the Hone it felf. The other part of the Razor / /, which is polifh'd on a grinding-ftone, appear'd much rougher then the other, looking al- moft like a plow'd field, with many parallels, ridges, and furrows, and a cloddy, as 'twere, or an uneven furface : nor fhall we wonder at the roughnefles of thofe fiirfaces , fince even in the moft curious wrought Glaltesfor Microfcopes, and other Optical ufes, I have, when the Sun has lhcne well on them , difcover'd their furface to be varioufly raz'd or fcratched, and to confift of an infinite of fmall broken furfaces, which re- flect the light of very various and differing colours. And indeed it feems impoffible by Art to cut the furface of any hard and brittle body fmooth, fince Vntte, or even the moft curious Powder that can be made ufe of, to polifhfuch a body, muft confift of little hard rough particles, and each of them muft cut its way, and confequently leave fbme kind of gutter or
furrows
Ml CROC RA P HI A* 5
furrow behind it. And though Nature does fecm to do it very readily in all kinds of fluid bodies , yet perhaps future obfervators may difcover even thcfealfo rugged $ it being very probable, as I elfevvhere (hew, that fluid bodies are made up of fmall folid particles varioully and Itrongly mov'd, and may find reafbn to think there is fcarce a furface in rerum na* tura perfectly fmooth. The black fpot m //, I ghefs to be fome fmall fpeck of ruft, for that I have oft obferv'd to be the manner of the working of Corrofive Juyces. To conclude, this Edge and piece of a Razor, if it had been really fuch as it appcar'd through the Microfiope, would fcarce- ly have ferv'd to cleave wood, much left to have cut off the hair of beards^ unlcfs it were after the manner that Lncian merrily relates Charon to have made ufe of,when with a Carpenters Axe he chopd off the beard of a fage Philofopher, whole gravity he very cautioufly feard would indanger the overfetting of his Wherry.
Obferv. III. Of fine Lawn, or Lirmen Cloth.
THis is another product of Art, A piece of the fineft Lawn I was able Schem-lS> to get, fo curious that the threads were fcarce difcernable by the na- *' ked eye,and yet through an ordinary Microfcope you may perceive what a goodly piece of coarfe Matting it is '■, what proportionable cords each of its threads are, being not unlike, both in ihape and fize, the bigger and coarfer kind of Jingle Rope-j/arn^wheYewith. they ufually make Cables. That which makes the Lawn fo tranfparent, is by the Microfcope^ nay by the naked eye, if attentively viewed, plainly enough evidenced to be the multitude of fquare holes which are left between the threads, appearing to have much more hole in reipecl: of the intercurrent parts then is for the moft part left in a latthe-window, which it does a little refemble, onely the crofling parts are rouridand not flat.
Thefe threads that compofe this fine contexture, though 'they are as fmall asthofe that conftitute the finer forts of Silks, have notwithstanding nothing of their glofiie, pleafant,and lively reflection. Nay, I have been informed both by the Inventor himfelf, and feveral other eye-witnefles, that though the flax,out of which it is made,has been (by a Angular art, of that excellent Perfon, and Noble Vertuofo, M. Charts Howard^ brother to the Duke of Norfoll()(6 curioufly drefs'd and prepar'd,as to appear both to the eye and the touch, full as fine and asglojfie, and to receive all kinds; of colours,as well as Sleave-Silk 5 yet when this Silken Flax is twifted into threads, it quite lofeth its former lufter, and becomes as plain and bale a thread to look on, as one of the fame bignefs, made of comrflon Flax.
The reafbn of which odd Phenomenon feems no other then this 5 that though the curioufly dreft Flax has its parts fo exceedingly fmall, as to equallize, if not to be much fmaller then the clew of the Silk-worm, efpe- cially in thinnefs, yet the differences between the figures of the confti- tuting filaments are fo great, and their fubftances fo various, that whereas
C thofe
6 Micrograph i a.
thofe of the Silk^ arc fmall,round, hard, tranfparent, and to their bignefs proportionally Jiiff, fo as each filament prefervcs its proper Figure, and confequently its vivid reflection intire, though twifted into a thread, if not too hard 5 thofe of Flax are flat, limber, fofter3and left transparent, and in twifting into a thread they joyn,and lie fo clofe together,as to lofe their own, and deftroy each others particular reflections. There feems there- fore three Particulars very requilite to make the fo dreft Flax appear Silk alfo when fpun into threads. Firft, that the fubftance ofitfhouldbe made more clear and tranfparent, Flax retaining in it a kind of opacating brown, or yellow 5 and the parts of the whiteftkind I have yetobferv'd with the Microfcope appearing white, like flaw'd Horn or Glafs, rather then clear, like clear Horn or Glals. Next that, the filaments fhould each of them be rounded, if that could be done,which yet is not fo very necefc fary, if the firft be perform' d, and this third, which is, that each of the fmall filaments be jlifned^ for though they be iquare, or flat, provided they be transparent and ftiff, much the fame appearances mud neceflarily follow. Now, though I have not yet made trial, yet I doubt not, but that both thefe proprieties may be alfo indued upon the Flax,and perhaps too by one and the fame Expedient, which fome trials may quickly inform any ingenious attempter of, who from the ufe and profit of fuch an Invention, may find rufficient argument to be prompted to fuch Inquiries. As for the tenacity of the fubftance of Flax, out of which the thread is made, it feems much inferiour to that of Silk, the one being a vegetable, the other an animal fubftance. And whether it proceed from the better con- coction, or the more homogeneous conftitution of animal fubftances above thole of vegetables, I do not here determine 5 yet fince I ge- nerally find, that vegetable fubftances do not equalize the tenacity of ani* mat, nor thefe the tenacity of fome purified mineral fubftances 5 I am very apt to think, that the tenacity of bodies does not proceed from the hamous, or booked particles, as the Epicureans, and fome modern Philojb- phers have imagin'd but from the more exacl: congruity of the confti- tuent parts, which are contiguous to each other, and lb bulky, as not to be eafily feparated, or fhatter'd, by any fmall pulls or concuffion of heat.
Obferv. I V. Qf fine waled Silky or Taffety.
schem. 3. f - 1 His is the appearance of a piece of very fine Tafiety-riband in the Ftl' »• J bigger magnifying Glafc, which you fee exhibits it like a very con- venient fubftance to make Bed-matts,or Door-matts of,or to ferve for Bee- hives, Corn-fcuttles,Chairs; or Corn-tubs,it being not unlike that kind of work,, wherewith in many parts in England,, they make fuch Utenfils of Straw,a little wreathed,and bound together with thongs of Brambles. For in this Contexture, each little filament, fiber, or clew of the Silk-worm, fcem'd about the bignefs of an ordinary Straw, as appears by the little ir- regular
'4
MlCROGRAPHlA.
regular pieces,* b^c ^and e ft The IVarp^ot the thread that ran crofting the Riband,appear'd like afingle Rope of an Inch Diameter 5 but the Woof, or the thread that ran the length of the Riband, appear'd not half (6 big. Each Inch of fix-peny-broad Riband appearing no left then a piece, of Matting Inch and half thick, and twelve foot fquare 5 a few yards of this, would be enough to floor the long Gallery of the Loure at r<tris. But to return to our piece of Riband : It affords us a not unpleaiant ob- ject, appearing like a bundle;, or wreath, of very clear and tranfparent Cylinders the Silk be white, and curioufly ting'd $ if it be colour'd,each of thole fmall homey Cylinders affording in fome place or other of them, as vivid a reflection, as if it.had been fent from a Cylinder of Glafs or Horn, In-fo-much, that the reflections of Red, appear'd as if coming from fo many Granates, ox Rubies'. The lovelinefs of the colours of Silks above thofe of hairy Stuffs,or Linnen,confifting as I elfe-where intimate,chiefiy in the tranfparency, and vivid reflections from the Concave.or inner iurface of the transparent Cylinder, as are alfo the colours of Precious Stones 5 for moft of the reflections from each of thefe Cylinders^ come from the Concave furfaceof the air, which is as 'twere the foil that incompafles the Cylinder. The colours with which each of thefe Cylinders are ting'd, feem partly to be fuperhcial, and fcicking to the out-fides of them ^ and partly^ to be imbib'd, or funck into the fubftance of them : for Silk, feeming to be little elfe then a dried thread of Glew, may be fuppos'd to be very eafily relaxt.and foftened,by being fteeped in warm, nay in cold, if pene- trant, juyces or liquors. And thereby thofe tinctures, though they tinge perhaps but a fmall part of the fubftance, yet being fo highly impregnated with the colour, as to be almoft black with it, may leave an impreflion ftrong enough to exhibite the defird colour. A pretty kinde of artifi- cial Stuff I have feen, looking almoft like tranfparent Parchment, Horn, or Ifing-glafs, and perhaps fome fuch thing it may be made of, which be- ing tranfparent, and of a glutinous nature, and eafily mollified by keep- ing in water, as I found upon trial, had imbib'd, and did remain ting'd with a great variety of very vivid colours, and to the naked eye, it look'd very like the fubftance of the Silk. And I have often thought, that pro- bably there might be a way found out, to make an artificial glutinous compofition, much refembling, if not full as good, nay better, then that Excrement,or whatever other fubftance it be out of which, the Silk-worm wire-draws his clew. If fuch a compofition were found, it were certain- ly an eafie matter to find very quick ways of drawing it out into fmall wires for ufe. I need not mention the ufe of fuch an Invention,nor the be- nefit that is likely to accrue to the finder,they being fufficiently obvious. This hint therefore, may, I hope, give fome Ingenious inquifitive Perfon an occafion of making fome trials, which if fuccefsfull, I have my aim, and I fuppofe he will have no occafion to be difpleas'd,
Obferv. V*
8
MlCROGRAPHIA.
Obferv. V. Of watered Silks, or Stufs*
Schtm, j. | Here are but few Artificial things that are worth obfeiving with a f*« *• J[ Microfcope \ and therefore I (hall fpeak but briefly concerbing them. For the Productions of art are fuch rude mif-fliapen things, that when view'd with a Microfcope jheve is little elfe obfervable5but their deformity. The mofr curious Carvings appearing no better then thofe rude Ruffian Images we find mentiond in rurchas, where three notches at the end of a Stick, flood for a face. And the moft fmooth and burnifii'd furfaces appear moft rough and unpolifht : So that my firft Reafon why I (hall add but a few obfervations of them, is, their mif-lhapen form ^ and the next, is their ufeleisnefs. For why fhould we trouble our lelves in the examination of that form or fhape (which is all we are able to reach with a Microfcope) which we know was dcfign'd for no higher a ufe, then what we were able to view with our naked eye } Why fhould we endeavour to difcover myfteries in that which has no fiich thing in it ? And like Rabbins find out Caballifms, and oenigm&s in the Figure, and placing of Letters, where no fuch thing lies hid : whereas in natural forms there are fome fofmall, and fo curious,and their defign'd bufihefs lb far remov'd beyond the reach of our fight5that the more we magnify the object, the more excellencies and myfteries do appear ■> And the more we difcover the imperfections of our fenfesj and the Omnipotency and Infinite perfections of the great Crea- tour. I (hall therefore onely add one or two Obfervations more of artifi- cial things, and then come to the Treaty concerning fuch matters as are the Productions of a more curious Workman. One of thefe^fhall be that of a piece of water'd Silk, reprefented in the fecond Figure of the third Scheme^sit appear d through the leaft magnifying Glafs. A B. fignifying the long way of the SturT,and C D the broad way. This Sturl, if the right fide of it be looked upon, appears to the naked eye, all over fo waved, undulated, or grain'd, with a curious, though irregular variety of brigh- ter and darker parts, that it adds no fmall gracefulnefs to theGlofsof it. It is fo known a propriety, that it needs but little explication, but it is ob- fervable, which perhaps every one has not considered, that thofe parts which appear the darker part of the wave, in ^ne pofition to the light, in another appears the lighter,and the contrary ^and by this means the undu- lations become tranfient, and in a continual change,according as the po- fition of the parts in refpe&of the incident beams of light is varied. The reafon of which odd phenomena, to one that has but diligently examin'd it even with his naked eye, will be obvious enough. But he that obferves it with a Microfcope^ may more eafily perceive what this Proteus is. and how it comes to change its fhape. He may very eafily perceive, that it proceeds onely from the variety of the Reflection* of light, which is caus'd by the various fijape of the Particles^ or little protuberant parts of the thread that compofe the furface j and that thofe parts of the waves that
appear
M iCROGRAPHlAo
appear the brighter.throw towards the eye a multitude of fmall reflexi- ons of light, whereas the darker fcarce afford any. The reafon of which reflection, the Microfcope plainly difcovers, as appears by the Figure, In which you may perceive, that the brighter parts of the furface confift of an abundance ot large and ftrong renections,denoted by a, a, a, a, a, 8cc. for the furfaces of thofe threads that run the long way, are by the Mecha- nical procefs of watering, creasd or angled in another kind of pofture then they were by the weaving : for by the weaving they are onely bent round the warping threads j but by the watering, they are bent with art angle, or elbow, that is in ftead of lying, or being bent round the threads, as in the third Figure, a, a, a, a, a, are about b,b,b (b,b,b reprefenting the ends,as 'twere, of the crofsthreads,they are bent about) they are creas'd on the top of thole threads, with an angle, as in the fourth Figure, and that With all imaginable variety 5 fo that,whereas before they reflected the light onely from one point of the round furface, as about c, c, c, they now when water'd, reflect the beams from more then half the whole fur- face,as de,de,de, and in other pofturcs they return no reflections at all from thofe furfaces. Hence ip one pofture they compofe the brighter parts of the waves,in another the darker. And thefe reflections arealfo varied, according as the particular parts are varioufly bent. The reafon of which creafing we (hall next examine 3 and here we muit fetch our in-* formation from the Mechanifm or manner of proceeding in this operation 3 which, as I have been inform'd, is no other then this.
They double all the Stuff that is to be water'd. that is,they create it juft through the middle of it, the whole length of the piece, leaving the right fide of the Stuff inward, and placing the two edges, or filvages juft upon one another,and,as near as they can,place the wale fo in the doubling of it, that the wale of the one fide may lie very near parallel, or even with the wale of the other 3 for the nearer that pofture they lie, the greater will the watering appear 3 and the more obliquely,or acrofs to each other they lie, the fmaller are the waves. Their way for folding it for a great wale is thus : they take a Pin,and begin at one fide of the piece in any wale,and lb moving it towards the other fide, thereby direct: their hands to the op- pofite ends of the wale, and then, as near as they can, place the two op- .pofite ends of the fame wale together, and fo double, or fold the whole piece, repeating this enquiry with a Pin at every yard or two's diftance through the whole length 3 then they fprinkle it with water,and fold it the longways, placing between every fold a piece of Paftboard, by which means all the wrong fide of the water'd Stuff becomes flat, and with little wales, and the wales on the other fide become the more protuberant 3 whence the creafings or angular bendings of the wales become the more perfpicuons:7 Having folded it in this manner,they place it with an inter- jacent Paftboard into an hot Prefs, where it is kept very violently preft, till it be dry and ftifT} by which means, the wales of either contiguous fides leave their own imprefiions upon each other , as is very mani- feit by the fecond Figure, where 'tis obvious enough, that the wale of the piece A B C D runs parallel between the pricked lines e/, ef, ef, and as
D manifeft
IO
MlCROGRAPHIA
manifeft: to difcern the impreflions upcn thefe wales, left by triofe that were preft upon them,which lying not exactly parallel with them,but a lit- tle athwart them , as is denoted by the lines ofy o o o0gh. gh,gh3 between which the other wales did lie parallel^they are fo varioufly,and irregular- ly creas'd that being put into that ftiape when wet,and kept fo till they be arie, they fo fet each others threads, that the Moldings remain almoft as long as the Stuff lafts.
Hence it may appear to any one that attentively confiders the Figure, why the parts of the wale <*, a, a, a, a, <?, fhould appear bright } and why the parts fhould appear fhadowed, or dark} why fbme, as
d^d^d^d, (hould appear partly light,and partly dark : the varieties of which reflections and fhadows are the only caufe of the appearance of wa- tering in Silks, or any other kind of StufTs.
From the variety of reflection, may alfo be deduc'd the caufe why a fmall breez or gale of wind ruffling the furface of a fmooth water, makes it appear black 5 as alfo,on the other fide, why the fmoothing or burnilh- ing the furface of whitened Silver makes it look black $ and multitudes of other phenomena might hereby be folv'd, which are too many to be here infifted on.
. Obferv. VI. Of fmall Glafs Canes.
THat I might be fatisfi'd, whether it were not poffible to make an Artificial pore as fmall as any Natural I had yet found, I made fe- veral attemps with fmall glafs pipes, melted in the flame of a Lamp, and then very fuddenly drawn out into a great length. And, by that means without much difficulty. I was able to draw fome almoft as fmall as a Cobweb^ which yet, with the Microfcope, I could plainly perceive to be perforated, both by looking on the ends of it, and by looking on it againfi the light 5 which was much the eafier way to determine whether it were folid or perforated 5 for, taking a fmall pipe of glafs, and clofing one end of it, then filling it half full of water, and holding it againfi the light, I could, by this means, very eafily find what was the differing afpett of a folid and a perforated piece of glafs 5 and fo eafily diftinguifh, without feeing either end, whether any Cylinder of glafi I look 'don, were a folid ftic^ or a hollow cane. And by this means,I could alfb prefently judge of any fmall filament of glafs, whether it were hollow or not, which would have been exceeding tedious to examine by looking on the end. And many fuch like ways I was fain to make ufe of, in the examining of di- vers other particulars related in this Book, which would have been no eafie task to have determined meerly by the more common way cf look- ing on, or viewing the Object. For, if we confider firft, the very faint light wherewith the object is enlightened, whence many particles ap- pear opacouS) which when more enlightned, appear very tranfparent, fb that I was fain to determine its tranfparency by one glafs, and its texture by another Next, the nnmanageabknefs of moft Objetfs, by reafbn
MlCROGRAPHlA* 1*1
of theirfmalnefi, 3. The difficulty of finding the defircd point, and of placing it lb, as to reflect the light conveniently for the Inquiry, Laftly, ones being able to view it but with one eye at once, they will appear rio fmall objlr all ions, nor arc they eafily remov'd without many contrivan- ces. But to proceed, I could not find that water, or lome deeply tingd liquors would in fmall ones rife fo high as one would expect 5 and the highefi I have found it yet rife in any of the pipes I have try'd, was to 2 1 inches above the level of the water in the veflel : for though I found that in the fmall pipes it would nimbly enter at firfr, and run about 6 or 7 inches upwards 5 yet I found it then to move upwards fo flow, that I have not yet had the patience to obferve it above that height of 21 in- ches (and that was in. a pretty large ripe, in comparifon of thofe I for- merly mentioned $ for I could obierve the progrefs of a very deep tingd liquor m it with my naked eye, without much trouble 5 whereas many of the other pipes were fo very fmall, that unlefs in a convenient pojlure to the light, I could not perceive them :) But 'tis very probable., that a greater patience and ajjiduity may difcover the liquors to rife, at leaftto remain fufpended, at heights that I fhould be loath now even to ghefs at, if at leaft there be any proportion kept between the height of the afcending liquor, and the bignefs of the holes of the pipes.
An Attempt for the Explication of this Experiment.
My Conje&ure, That the unequal height of the furfaces of the water, proceeded from the greater prejjure made upon the water by the Air without the Tipes ABC, then by that within them , I (hall endeavour to confirm from the truth of the two following Proportions:
The firft. of which is, That an unequal prejjure of the incumbent Air will caufe an unequal height in the water s Surfaces.
And the fecond is, That in this experiment there is fuch an unequal prejjure.
That the firfl: is true, the following Experiment will evince. For if you take any Veflel fo contrived, as that you can at pleafure either /«- creafe or diminijl) the prejjure of the Air upon this or that part of the Su- perficies of the water, the equality of the height of thofe parts will pre- fently be lojl 5 and that part of the Superficies that fuftains the greater pref fitre: will be injerior to that which undergoes the lefs. A fit Veflel for this purpofe, will be an inverted Glafs Syphon, fuch an one as is delcri- bed in the Sixth Figure. For if into it you put Water enough to fill it as high as A B, and gently blow in at D, you (hall deprefs the Superficies J?, and thereby raife the oppofite Superficies A to a confiderable height } and by gently judging you may produce clean contrary erTe&s.
Next, That there is fuch an unequal prejjure, I fhall prove from this, 7 hat there is a much greater incongruity of Air to Glafs ^andfome other Bodies y then there is of Water to the fame,
D 2 By
Mi CROGRAPHIA.
By Congruity, I mean a property of a fluid Body, whereby any part of it is readily united with any other part, either of it felf or of any other Simi- lar, fluid, or folid body : And by Incongruity a property of a fluid, by which it is kindred from uniting with any dijfimilar,fluid,or folid Body.
This laft property, any one that hath been obfervingly converfant about fluid Bodies, cannot be ignorant of. For (not now to mention feveral Chymical Spirits and Oyls, which will very hardly, if at all, be brought to mix with one another infomuch that there may be found fome 8 or 9, or more, feveral diftinct Liquors, which fwimming one up- on another, will not prefently mix) we need feek no further for Exam- ples of this kind in fluids, then to obferve the drops of rain falling through the air, and the bubbles of air which are by any. means conveyed under the forface of the water ^ or a drop of common Sallet Oyl fwimming upon water. In all which, and many more examples of this kind that might be enumerated, the incongruity of two fluids is eahly difcernable. And as for the Congruity or Incongruity of Liquids, with feveral kinds of firm Bodies, they have long fince been taken notice of, and called by the Names of Drinefs and Moifiure (though thefe two names are not compre- hensive enough, being commonly ufed to fignifie only the adhering or not adhering of water to fome other folid Bodies)o£ this kind we may ob- ferve that water will more readily wet fome woods then others 5 and that water, let fall upon a Feather, the whiter fide of a Colwort, and fome other leaves, or upon almoft any dufly, unttuous, or refinous fuperficies, will not at all adhere to them, but eafily tumble off from them, like a folid Bowl whereas, if dropt upon Linnen, Paper, Clay, green Wood, &cc. it will not be taken off, without leaving fome part of it behind adhering to them. So guickefdver , which will very hardly be brought to fiick^to any vegeta- ble body, will readily adhere to, and mingle with, feveral clean metalline bodies.
And that we may the better finde what the caufe of Congruity and Incongruity in bodies is, it will be requifite to confider, Firft, what is the caufe of fluidnefs 5 And this, I conceive, to be nothing elfe but a certain ptlfe or Jbake oiheat } for Heat being nothing elfe but a very briskjinA ve- hement agitation of the parts of a body (as I have elfwhere made proba- bable) the parts of a body are thereby made fo loofe from one another, that they eafily move any way, and become fluid. That I may explain this a little by a grofs Similitude, let us foppofeadifhof fandfet upon fome body that is very much agitated, and fhaken with fome quicks and firong vibrating motion,^ on a Milfone turn'd round upon the under ftone very violently whilft it is empty -,or on a very ftiffDr#«?-head,which is ve- hemently or very nimbly beaten with the Drumfticks. By this means, the fand in the difh, which before lay like a J;///and una&ive body, be- comes a perfeCt fluid ^ and ye cannofooner make a hole in it with your finger, but it is immediately/^^ up again, and the upper furface of it levell d. Nor can you bury a light body, as a piece of Cork under it, but it prefently emerges or fwims as 'twere on the top 5 nor can you lay a heavier on the top of it, as a piece of Lead, but it is immediately buried
in
MiCROGRAPHlA.
in Sand, and (as 'twere) finks to the bottom. Nor can you make a hole in the fide of the Difti, but the land fhall run out of it to a level, not an obvious property of a fluid body, as fucli, but this dos imitate $ and all this meerly caufed by the vehement agitation of the conteining veflel 5 for by this means, each (and becomes to have zvibrative or dancing mo* tion, lb as no other heavier body can reji on it, unlefs fufieind by fome other on either fide : Nor will it fuffer any Body to be beneath it, unlefs it be a heavier then it felf. Another Inftance of the ftrange loofening nature of a violent jarring Motion, or a ftrong and nimble vibrativc one, we may have from a piece of iron grated on very ftrongly with a file : for if into that a pin be fcrewd fo firm and hard, that though it has a convenient head to it, yet it can by no means be unferevp'd by the fin- gers if, I fay, you attempt to unferew this whilft grated on by the file, it will be found to undoe and turn very eafily. The firft of thefe Examples manifefts, how a body actually divided into fmall parts, becomes a fluids And the latter manifefts by what means the agitation of heat fo eafily loofens and unties the parts of folid and firm bodies. Nor need we fup- pofe heat to be any thing clfe, befidesfuch amotion 5 for fuppofing we could Mechanically produce fuch a one quicksand firong enough, we need, not fpend/«e/ to melt a body. Now, that I do not fpeak this altogether groundlefs, I mull: refer the Reader to the Obfervations I have made up- on the mining fparks of Steel, for there he (hall find that the fame effects are produced upon fmall chips or parcels of Steel by the flame, and by a quick^ and violent motion $ and if the body otfteel may be thus melted (as I there (hew it may) I think we have little reafon to doubt that al- moft any other may not alfo. Every Smith can inform one how quickly both his File and the Iron grows hot with filing, and if you rub almoft any two hard bodies together, they will do the iame : And we know, that a fuflicient degree of heat caufes fluidity, in fome bodies much foon- er, and in others later 5 that is, the parts of the body of fome are fo laofe from one another, and fo unapt to cohere, and fo minute and little, that a very fmall degree of agitation keeps them always in the jiate of fluidity. Of this kind, I fiippofe, the Mther, that is the medium or fluid body, in which all other bodies do as it were fwim and move 5 and particularly, the Air, which feems nothing elfe but a kind of tin&ure oxfolution of ter- reftrial and aqueous particles dijjolv'd into it, and agitated by it, juft as the tinfture of Cocheneel is nothing but fome finer dijjoluble parts of that Concrete lick'd up or dijjolv'd by the fluid water. And from this Notion of it, we may eafily give a more Intelligible reafon how the Air becomes fo capable oiRarefaBion and Condenfation. For, as in tinctures, one grain of fome firongly tinging fubftance may fenftbly colour fome hundred thou- fand grains of appropriated L\quovs,fo as every drop of it has its proportio- nate (hare, and be fenfibly ting'd, as I have try'd both with Logwood and Cocheneel : And as fome few grains of Salt is able to infed as great a quantity,as may be found by precipitations, though not fo eafily by the fight or ajie $ fo the Air, which feems to be but as 'twere a tincture or faline fubftance, dijjolv d and agitated by the fluid and agil Mther 5may dif-
perfe
MiCROGRAPHIA.
perfe and expand it felf into a vafl fpace, if it have room enough, and infecl^as it were,every part of that fpace. But,as on the other fide^if there be but fome few grains of the liquor, it may cxtraB all the colour of the tinging fubftance, and may difolve all the Salt, and thereby become much more impregnated with thole fubftances, fo may all the air that fufc ficed in a rarifyd fiate to fill fome hundred thoufaud fpaces of ./Ether, be compris'd in only 0#e,but in a pofition proportionable denfe. And though we have not yet found out fuch Jlrainers for Tinctures and Salts as we have for the Air, being yet unable to feparate them from their diffolving liquors by any kind of filtre, without precipitation, as we are able to fe- parate the Air from the ./Ether by Glafs, and feveral other bodies. And though we are yet unable and ignorant of the ways of precipitating Air out of the ./Ether as we can Tin&tires, and Salts out of feveral dijjolvents^ yet neither of thefe feeming impojfible from the nature of the things, nor fo improbable but that fome happy future induftry may find out ways to effect them 5 nay, further, fince we find that Nature does really perform (though by what means we are not certain) both thefe actions, namely, by precipitating the Air in Rain and Dews, and by fupplying the Streams and Rivers of the World with frefh water, jlraind through fecret fob- terraneous Caverns : And fince, that in very many other proprieties they do fb exactly feem of the fame nature 5 till further obfervations or tryals do inform us of the contrary, we may fafely enough conclude them of the fame kind. For it feldom happens that any two natures have fo ma- ny properties coincident or the fame, as I have obferv'd Solutions and Air to have, and to be different in the reft. And therefore I think it nei- ther impcjfible. irrational, nay nor difficult to be able to predi& what is likely to happen in other particulars alfo, befides thole which Obfervation or Experiment have declared thus or thus 5 efpecially, if the circum- fiances that do often very much conduce to the variation of the effects be duly weigh 'd and confiderd. And indeed, were there not a probability of this, our inquiries would be endlefs, our tryals vain, and our greateff in- ventions would be nothing but the meer produU s of chance, and not of Reafon $ and, like Mariners in an Ocean, deftitute both of a Compajs and the fight of the Celejiialguids, we might indeed, by chance, Steer dire&ly towards our defired Port, but 'tis a thoufand to one but we mifs our aim. But to proceed, we may hence alfo give a plain reafon, how the Air comes to be darkped by clouds, &c. which are nothing but a kind of precipitati- on, and how thole precipitations fall down in showrs. Hence alfo could I very eafily, and I think truly, deduce the caufe of the curious ftxangu- lar figures of Snow, and the appearances of Haloes, d^c. and the liidden thickning of the Sky with Clouds, and the vanifhing and difappearing of thole Clouds again 5 for all thefe things may be very eafily imitated in a glafs of liquor, with fome flight Chymical preparations as I have often try'd, and may fomewhere elfe more largely relate, but have not now time to fet them down. But to proceed, there are other bodies that confift of particles more Grofs, and of a more apt figure for cohefton, and this re- quires a fomewhat greater agitation 3 fuch, I fuppofe 5. fermented vinous
Spirits
Ml CROG R A P H I A* 1$
Spirits, fevcral chymical Oils, w hich are much of kin to thofe Spirits, &c. Others yet require a greater, as water, and fb others much greater, for al- moft infinite degrees: For, I fuppole there are very few bodies in the world that may not be made aliquatenus fluid, by fome or other degree of agitation or heat. , .
Having therefore in fhort Cet down my Notion of a Fluid body, I come in the next place to confider what Congruity is and this, as I faid before, being a Relative property of a fluid, whereby it may be faid to be like or unlike to this or that other body, whereby it does or does not mix with this or that body. We will again have recourfe to our ibrmer Experi- ment, though but a rude one 5 and here if we mix in the difh fever al kinds of lands, fome of bigger, others of lefs and finer bulks, we (hall find that by the agitation the fine find will ejecl and throw out of it lelf all thofe bigger bulks of fmall fiones and the like, and thofe will be gathered toge- ther all into one place j and if there be other bodies in it of other natures, thofe alfo will bejeparated into a place by themfelves, and united or tum- bled up together. And though this do not come up to the higheft proper- ty of Congruity, which is a Coh<eJion of the parts of the fluid together, or a kind of attraction and tenacity, yet this does as 'twere fimdow it out, and fbmewhat refemble it} for juft after the lame manner, I fuppole thcpuljeof heat to agitate the fmall parcels of matter, and thole that are of 2i like bignefi, and figure, and matter, will hold, or dance together, and thofe which are of a differing kind will be thrufi or Jhov'd out from be- tween them 5 for particles that are all fimilar, will, like lb many equal mufical firings equally firetcht, vibrate together in a kind of Harmony or nnifon 5 whereas others that are difftmilar, upon what account fbever,un- lefs the difproportion be otherwife counter-ballanc'd, will, like Co many firings out of tune to thofe unifons, though they have the lame agitating pulfe, yet make quite differing kinds of vibrations and repercufflons, lb that though they may be both mov'd,yet are their vibrations fo different, and fo untund, as 'twere to each other, that they crofs and jar againft each other, and confequently, cannot agree together, but fly back^irom each other to their fimilar particles. Now, to give you an inftance how the difproportion of lome bodies in one refpefr, may be counter-ballanc'd by a contrary difproportion of the fame body in another refped, whence we find that the fubtil vinous Jpirit is congruous, or does readily mix with wa- ter, which in many properties is of a very differing nature, We may con- fider that a unifon may be made either by two firings of the fame bignefi, length, and tenfwn, or by two firings of the fame bignefi, but of differing tength,and a contrary differing tenfion-0 or %ly. by two firings of unequal length and bignefi, and of a differing tenfwn, or of equal length, and diffe- ring bignefs and tenfwn, and leveral other fuch varieties. To which three properties in firings, will correfpond three proprieties alfo in fand, or the particles of bodies, their Matter or Subfiance, their Figure or shape, and their Body or Hulk- And from the varieties of thefe three, may arife in- finite varieties in fluid bodies, though all agitated by the fame pulfe or vi- brative motion. And there may be as many ways of making Harmonies
M I C R O G R A P H I A
and Difcords with thefe, as there may be with mufical firings. Having therefore fcen what is the caufe of Congruity or Incongruity, thofe rela- tive properties of fluids, we may, from what has been faid, very eafily collect, what is the reafon of thole Relative proprieties alfo between flu- id bodies andjblid j forfince all bodies conliftof particles o£ fuch a Sub- fiance, Figure, and Bulkj^ but in fome they are united together more firm- ly then to be loofened from each other by every vibrative motion (though I imagine that there is no body in the world, but that fome degree of a- gitation may, as I hinted before, agitate andloofcn the particles fo as to make them fluid) thofe cohering particles may vibrate in the fame man- ner almoft as thofe that are loofe and become unifons or difcords, as I may fo fpeak, to them. Now that the parts of all bodies, though never fo Jo/id, do yet vibrate, I think we need go no further for proof, then that al/bod\es have fome degrees of heat in them, and that there has not been yet found any thing perfellly cold: Nor can I believe indeed that there is any fuch thing in Nature, as a body whole particles are at reft, or lazy and unaflive in the great Theatre of the World, it being quite contrary to the grand Oeconomy of the Univerfe. We fee therefore what is the rea- fon of the fympathy or uniting of fome bodies together, and of the anti- pathy or flight of others from each other : For Congruity teems nothing elfe but a Sympathy, and Incongruity an Antipathy of bodies 5 hence Jlmi- lar bodies once united will not eafily part, and dijfimilar bodies once dif joyn d will not eafily unite again 3 from hence may be very eafily dedue'd the reafon of thejujpenfion of water and Quickcfilver above their ulual fla- as I (hall more at large anon fhew.
Thefe properties therefore (alwayes the concomitants of fluid bodies) produce thele following vifible Ejfetfs :
Firft, They unite the parts of a fluid to its fimilar Solid, or keep them Jeparate from its dijjimilar. Hence gh/ickjfilver will (as we noted before} fticl^to Gold, Silver, Tin, Leaded, and unite with them : but r^«/offfrom Wood, Stone, Glafs, &c. if never fo little fcituated out of its horizontal le- vel$ and water that will wet fait and dijfblve it, will flip off from Tallow, or the like, without at all adhering 3 as it may likewife be oblerved to do upon a dufty fuperficies. And next they caufe the parts othomogene- al fluid bodies readily to adhere together and mix3 and of heterogeneal,\.o be exceeding averfe thereunto. Hence we find, that two fmall drops of water, on any luperficies they can roulon,will, if they chance to touch each other, readily unite and mix into One 3d drop : The like may be ob- ferved with two {mz\\ Bowls o£ guitkzfilvcr upon a Table or Glafs, pro- vided their furfaces be not dujly 5 and with two drops of Oyl upon fair water, &c. And further, water put unto wine, fait water, vinegar, fpirit
wine, or the like, does immediately (especially if they be Ihaken to- gether) difperfe it lelf all over them. Hence, on the contrary, we alio find, that Oyl of Tartar poured upon gHiick^filver, and Spirit of Wine on that Oyl, and Oyl of Turpentine on that Spirit, and Air upon that Oy/3though they be ftopt clofely up into a Bottle, and flaxen never fo much, they will by no means long fufTcrany of their bigger parts to be united or in- cluded
MlCROGRAPHlA
eluded within any of the other Liquors(by which recited Liquors,may be plainly enough reprefented the four Perrpatetical Elements^ and the rttor* lubtil /Ether above all.) From this property 'tis-, that a drop of route r does not mingle with, or vanilh into Air0 but is driven (by that Fluid equally protruding it on every fide) and forc't into as little afpace as it can pofc libly be contained in, namely, into a Round Globule. So likewife a lit- tle Air blown under the water ^ is united or thruft into a bubble by the ambient water. And a parcel cf guickzfilver enclofed with Air^ Water, or almoft any other Liquor^ informed into a round Ball.
Now the caufe why all thefe included Fluids, newly mentioned5 'or it many others as are wholly included, within a heterogeneous fluids are not exattly of a Spherical Figure (feeing that if caufed by thefe Principles only, it could be of no other) muft proceed from lome other kind of pre/fure againft the two oppofite flatted fides. This adventitious or acci- dental prep/re may proceed from divers caufes^ and accordingly muft di- verfifie the Figure of the included heterogeneous fluid : For feeing that a bocly may be included either w ith a fluid only, or only with a folid , or partly with a fluid, and partly with a folid, or partly with one fluid, and. partly with another 5 there will be found a very great variety of the ter- minating furfaies^ much differing from a Spherical^ according to the vari- ous refinance or preffure that belongs to each of thefe encompaflingbo4 dies.
Which Properties may in general be deduced from two heads' 5 Motion^ and Rett. For, either this Globular Figure is altered by a natu- ral Motion^ fuch as is Gravity 5 or a violent^ luch as is any accidental motion of the fluids, as we fee in the wiftd ruffling up the water,and the purlings of Streams^ and foaming of C at arracls, and the like. Or thirdly, By the Reft^ Firmnefs and Stability of the ambient Solid. For if the including Solidbe of an angular or any other irregular Form, the included fluid will be near of the likens a Pint-P*tf full of water a Bladder full of Air. And next, if the including or included fluid have a greater gravity one than another,then will the globular Form be depreft into anEt/ipticojphericat: As if, for example, we fuppofe the Circle A B C D, in the fourth Figure^ to reprefent a drop of water , snuck^fdver ', or the like, included with the Air or the like .. which fuppolmg there were no gravity at all in either of the fluids^ or that the contained and containing were of the fame weighty would be equally comprett into an exactly /phericalbody (the ambient fluid forcing equally againft every fide of it. ) But fuppofing either a greater gravity in the included , by r'eafon whereof the parts of it being preft from A towards and thereby the whole put mto motion ^ and that motion being kindred by the rejiftance of the jubjaccnt parts of the ambient, the globular Figure A D B C will be depreft into the Elliptic- fpherical, E G F H. For the fide A is detruded to E by the Gravity } and B to F by the rejiftance of the fubjacent medium : an & therefore C muft neceflarily be thruft to G5 and D to H. Or elfe, fuppofing a great** ^grdvi- ty in the ambient^ by whofe more then or di nary pre/Jure againft thie under fide of the included globule } B will be forced to F, and by its refiftance of
E the
MlCROGRAPHIA.
the motion upwards , the fide A will be depreft to E, and therefore C being thruft to G and D to H 3 the globular Figure by this means alfo will be made an Elliptico-fpherical. Next if a fluid be included partly with one, and partly with another fluid, it will be found to be (haped diverfly , ac- cording to the proportion of the gravity and incongruity of the 3 fluids one to another : As in the fecond Figure, let the upper MM At be ^/r,the middle L M N 0 be common Oyl, the lower O 0 0 be Water, the Oyl will be form'd, not into a Jpherical Figure, fuch as is reprefented by the pricked Line, but into fuch a Figure as LMN O, whofe fide LMN will be of a flatter EllipticalF'igure, by reafon of the great difproportion between the Gravity of Oyl and Air, and the fide L O M ofarounder^ becaufe of the fmaller difference between the weight of Oyl and Water. LMy,Theglobular Figure will be changed,if the ambient be partly fluid and partly folid. And here the termination of the incompafled fluid to- wards the incompafling is (hap'd according to the proportion of the con- fruity or incongruity of the fluids to the folids , and of the gravity and incongruity of the fluids one to another. As fuppofe the fub jacent me- dium that hinders an included fluids defcent,be a folid , as let K I, in the fourth Figure, reprefent the fmooth luperficies of a Table 3 E G F H, a parcel of running Mercury 3 the fide G F H will be more flatted , ac- cording to the proportion of the incongruity of the Mercury and Air to the Wood,an& oi the gravity of Mercury and Air one to another 5 The fide CE H will likewile be a little more depreft by reafon the fub jacent parts are now at reft, which were before in motion.
Or further in the third Figure, let A I L D reprefent an including fo- lid medium of a cylindrical ftiape ( as fuppofe a fmall Glafs Jar ) Let FGE MM reprefent a contain a fluid, as water 5 this towards the bot- tom and fides, is figured according to the concavity of the Glafs : But its upper Surface, ( which by reafon of its gravity, ( not confidering at all the Air above it, and fo neither the congruity or incongruity of either of them to the Glafs) Ihould be terminated by part of a Sphere whofe dia- meter fhould be the fame with that of the earth, which to our fenfe would appear a ftraight Line, as F G E, Or which by reafon of its having a greater congruity to Glafs than Air has, ( not confidering its Gravity ) would be thruft into a concave Sphere, as C H B, whofe diameter would be the fame with that of the concavity of the Veflel : ) Its upper Surface, I lay, by reafon of its having a greater gravity then the Air, and having likewife a greater congruity to Glals then the Air has5 is terminated, by a concave Elliptico-JphericalVigxxve, as C K B. Fcr by its congruity it eafily conforms it felf, and adheres to the daft, and conftitutes as it were one containing body with it, and therefore ihould thruft the contained Air on that fide it touches it,into a fphericalF'iguxe, as B H C, but the motion of Gravity depreffing a little the Corners B and C, reduces it into the afore- laid Figure C KB. Now that it is the greater congruity of one of the two contiguous fluids,then of the other,to the containing folid,that caufes the feparating farfaces to be thus or thus figured : And that it is not be- caufe this or that figurated furface is more proper, natural, or peculiar to
one
. M ICROGRAP HI A. I#
one of thefe fluid bodies,thcn to the other,wilI appear from this J that the fame fluids will by being put into differing^//^/ i change t\\Q\v fiy facet. For the fame water, which inaClafs Or wooden Vcllel will have a con- cave luiface upwards,and will rife higher in a fmaller then a greater Pipe, the fame water, I lay, in the fame Pipes greafed over or oylcd5 will pro- duce quite contrary effects } for it will have a protuberant and convex fur- face upwards, and will not rife fo high infmall,asiri bigger Pipes : Nay, in die Vt 1 v iame iolicl Veflel . you may make the very fame two contigu- ous Liquids to alter their Surfaces $ for taking a final! Winc-glti(s5-dr fuch like Veliel, and pouring water gently into it, you fhall perceive the for- face of the v/ater all the way concave, till it ri(e even with the top, when you (hall find it ("if you gently and carefully pour in more) to grow very protuberant and convex 5 the reafon of which is plain , for that the folid fides of the containing body are no longer extended , to which the water does more readily adhere then the air^ but it is henceforth to be included with air, which would reduce it into a hemifphere, but by reafon of its gravity, it is flatted into an Oval Quicksilver alfo which to Glafs is more incongruous then Air ( and thereby being put into a Glafi-pipe, will not adhere to it, but by the more congruous air will be forced to have a very protuberant furface , and to rile higher in a greater then a feiler* Pipe ) this Quicksilver to clean Metal, efpecially to Gold,S therein Lead, &c. Iron excepted,is more congruous then Air , and will not only ftick to it,but have a concave Surface like rvatet, and rife higher in a lefs, then in a greater Pipe.
In all thefe Examples it is evident , that there is an extraordinary and adventitious force, by which the globular Figure of the contained hetero- geneous fluid is altered } neither can it be imagined, how it fhould other- #wife be of any other Figure then Globular : For being by the heterogene- ous fluid equally protruded every way,whatfoever part is protuberant, will be thereby depreji. From thiscaufeit is, that in its effects It does very much refemble a round Spring (fuch as a Hoop.) For as in a round Spring there is required an additional prejjure againft two oppohte fides , to re- duce it into an Oval Form , or to force it in between fhe fides of a Hole, whofe Diameter is lefs then that of the Spring, there muft be a considera- ble force or protrujion againft the concave or inner fide of the Spring 5 So to alter this j^m^/conftituticn of an included fluid body , there is re- quired more preffiire againft oppofite fides to reduce it into an Oval-^ and, to prefs it into an Hole lefs in Diameter then it felf, it requires a great etpro- irufton againft all the other fides. What degrees of force are requifite to reduce them into longer and longer Ovals , or to prels them into lefs and lefs holes, I have not yet experimentally calculated 5 but thus much by experiment I find in general , that there is alwayes required a greater prefliire to clofe them into longer Ovals , or protude them into frrfaller holes. The neceility and realbn of this, were it requifite,! could eafily ex- plain: but being not foneceflary,. and requiring more room and time then I have for it at prefent , I fhall here omit it 5 and proceed to fhew, that this may be prefently found true , if Experiment be made with a
E 1 round
M
I CROGRAP HIA
round spring f the way of making which trials is obvious enough. ) And with the fluid bodies of Mercury > Air, &c, the way of trying which, will be fomewhat more difficult } and therefore I (hall in brief defcribe it. He therefore that would try with Air , muft firft be provided of a Clafs-pipe, made of the fhape of that in the fifth Figure , whereof the fide A B, re* prefents a ftraight Tube of about three foot long, C,reprefents another part of it,which confifts of a round Bubble 5 fo ordered,that there is left a pajjage or hole at the top , into which may be fattened with cement feveral fmall Pipes of determinate cylindrical cavities : as let xhe hollow of
F.
G. H. I. K. L. M.j
> be <- f » I of an inch.
h x
X 3*
There may be added as many more , as the Experimenter (ball think n"t> with holes continually decreafing by known quantities, fo far as his fenfes are able to help him 5 I fay, fo far, becaufe there may bt made Pipes fo fmall that it will be impoffible to perceive the perforation with ones na- ked eye,though by the help of a Microfcope, it may eafily enough be per- ceived : Nay, I have made a Pipe perforated from end to end, fo fmall, that with my naked eye I could very hardly fee the body of it, infomuch that I have been able to knit it up into a knot without breaking : And more accurately examining one with my Microfiope, I found it not fo big as a fixteenth part of one of the fmaller hairs of my head which was o£ the fmaller and finer fort of hair, fo that fixteen of thefe Pipes bound fag- got-wife together, would but have equalized one fingle hair 5 how fmall therefore muft its perforation be ? It appearing to me through the Mi cro" fcope to be a proportionably thickfided Pipe.
To proceed then, for the trial of the Experiment, the Experimenter muft place the lube A B, perpendicular, and fill the Pipe F ( cemented in- to the hole E ) with water, but leave the bubble C full of Air, and then gently pouring in water into the Pipe A B, he muft obferve diligently how high the water will rife in it before it protrude the bubble of Air C, through the narrow paflage of F, and denote exattly the height of the Cylinder of water , then cementing in a fecond Pipe as G, and filling it with watery he may proceed as with the former, denoting likewife the height of the Cylinder of water , able to protrude the bubble C through the parTage of G, the like may he do with the next Pipe^and the next^dv. as far as he is able : then comparing the feveral heights of the Cylinders $ with the feveral holes through which each Cylinder did force the air ("ha- ving due regard to the Cylinders of water in the fmall Tube s) it will be very eafie to determine, what force is requifite to prefs the Air in- to fuch and fuch* hole3 or ( to apply it to ourprefent experiment )
how
Ml CROG RA P H I A- 21
how much of the preflure of the Air is taken off' by its ingrcGinto fmal- ler and fmaller holes. From the application of which to theentringof the Air into the bigger hole of the Vejfti* and into the fmaller hole of the ripe, we fhall clearly find, that there is a greater preflure of the air upon the water in the Veflelox greater/* ipe, then there is upon that in the lefler pipe: For (nice the preilure of the air every way is found to be equal, t hat is, as much as is able to preis up and fuftain a Cyltnder of Quicksilver of two foot and a half high, or thereabouts 5 And fince of this preflure fo many more degrees are required to force the Air into a fmaller then into a greater hole that is full of a more congruous fluid. Andlaftly, fince thofe degrees that are requilite to prefs it in, are thereby taken off from the Air within , and the Air within left with fo many degrees of preflure lefs then the Air without 5 it will follow*, that the Air in the lefs Tube or pipe , will have lefs preflure againft the fuperficies of the water therein, then the Air in the bigger : which was the minor Proportion to be proved.
The Conclufion therefore will neceflarily follow, viz,. That this une* qualprefure of the Air caufed by its ingref into unequal holes, k a caufe Jujjj- cient to produce this ejfett , without the help of any other conc urrent } and therefcre is probably the principal (if not the only) caufe of thefe Phano* mena.
This therefore being thus explained , there will be divers Phenomena explicable thereby, as, the rifing of Liquors in a Filtre, the rifing of Spirit of Wine, Oyl^ melted Tallow, &c. in the Week, of a Lamp, ( though made of fmall Wire, ihreeds of AsLefius, Strings of Glafs, or the like ) the rifing of Liquors in a Spunge, piece of Bread,S and, &c perhaps alio the amend- ing of the Sap in Trees and Plants, through their fmall, and fome of them imperceptible pores, (of which I have faid more, on another occafion ) at leaft the pafling of it out of the earth into their roots. And indeed up* on the confideration of this Principle , multitudes of other ufes of it oc- curr d to me, which I have not yet fo well examined and digefted as to propound for Axioms , but only as Queries zn&Conjetfures which may ferve as hints toward fome further difcoveries.
As firfr. Upon the confideration of the congruity and incongruity of Bo* dies,as to touch, I found alfo the like congruity and incongruity Cif I may fo fpeak ) as to the Tranjh/itting of the Raies of Light : For as in this re- gard ,water ( not now to mention other Liquors ) feems nearer of affini- ty to Glafs then Air, and Air then Quicksilver : whence an oblique Ray out of Glafs, will pafs into water with very little refrat~lion from the perpendi- cular, but none out of Glafs into Air, excepting a direti, will pafs without a very great refraction from the perpendicular, nay any oblique Ray un- der thirty degrees, will not be admitted into the Air at all. And Quiche fiver will neither admit oblique or direct, but reflects all 5 feeming, as to the tranfmitting of the Raies of Light , to be of a quite differirlg confti- tution,fi om that of Air ,Wattr plafs , &c. and to refemblemoft thofe opa- cous and ftrong reflecting bodies of Metals : So alfo as to the property of cohefion or congruity , Water fcems to keep the fame order , being
more
22
MlCROGRAPHIA.
more congruous to Glafs then Air , and Air then Quickfilver.
A Second thing ( which was hinted to me, by the consideration of the included fluids globular form , caufed by the protrufion of the ambient heterogeneous fluid ) was, whether the Phenomena of gravity might not by this means be explained,by fuppofing the Globe of Earth, Water, and Air to be included with a fluid, heterogeneous to all and each of thcrr^ (b fubtil , as not only to be every where interjperjed through the Air, (for rather the air through it ) but to pervade the bodies of Glafs , and even the clojeji Metals , by which means it may endeavour to detrude all earth- ly bodies as tar from it as it can 5 and partly thereby ,and partly by other of its properties may move them towards the Center of the Earth. Now that there is fome luch fluid,I could produce many Experiments and Rea- lons , that do feem to prove it : But becaufe it would ask fome time and room to fet them down and explain them, and toconfiderandanfwer all the Objections ( many whereof I forefee ) that may be alledged againft it 5 I fhall at prelent proceed to other (Queries, contenting my felf to have here only given a hint of what I may (ay more elfwhere.
A Third Query then was , Whether the heterogeneity of the ambient fittid may not be accounted a fecondary caufeoi the roundnefs or globular formoi the greater bodies of the world ,fuch as arethofe of the Sun,Stafs9 and Vianet s , the Jubjiance of each of which feems altogether heterogene- ous to the ar cum- ambient fluid aether'} And of this I (hall fay more in the Obfervation of the Moon.
A Fourth was. Whether the globular form of the fmaller parcels of matter here upon the Earthy as that of Fruits, Pebbles, or Flints , &ct C which feem to have been a Liquor at firft ) may not be caufed by the! heterogeneous ambient fluid. For thus we fee that melted Glafs will be naturally formed into a round Figure \ fo likewife any fmall Parcel of any fujible body , if it be perfectly enclofed by the Air , will be driven into a globular Form 5 and,when cold, will be found a folid Ball. This is plainly enough manifefted to us by their way of making Jbot with the drops of Leadi which beinga very pretty curiofityjand known but to a very few, and having the liberty of publishing it granted me, by that Eminent Vir- tuofo Sir Robert Moray , who brought in this Account of it to the Rdyal So- ciety, I have here tranferibed and inlerted.
To make fmall (hot of different fizes ; Communicated by his * Highnefs P. R.
*cu v*H w{>ndo '{ns '{cn ^Uj^biwpaq xlvmov I nor.
TAke Lead out of the Pig what quantity you pleafe, melt it down? fir and clear it with an iron Ladle , gathering together the bhckifb parts that fwim at top like fcum, and when you fee the co- lour of the clear Lead to begreeniftjjbut no foonerrfrew upon it Auri-
pigmentum
MlCROGRAPHlAi 23
pigmentum powdered according to the quantity of Lead, about as much as will lye upon a half Crown piece will fervefor eighteen Or twenty pound weight offome forts of Lead ; others will require more, dr kfi. After the Auripigmentum is put in, fir the Lead well, and the Auripigmentum will flame: when the flame is over, take out fome of the Lead in a Ladle having a lip or notch in the brim for conveni- ent pouring out of the Lead,and being well warmed among fl the melted Lead, and with a ftickmake fome fingle drops of Lead trickle out of the Ladle into water in d Glafs , which if they fall to be round and without tails, there it Auripigmentum enough put in, and the temper of the heat is right, otherwife put in more. Then lay two bars of Iron ( or fome more proper Iron-* oil made on purpofe) upon a Pail of wa- ter,and place upon them a round Plate of Copper, of the fze and figure of an ordinary large Pewter or Silver Trencher, the hollow whereof is to be about three inches over , the bottom lower then the brims about half an inch, pierced with thirty, forty, or more fmall holes-, the fmaller the holes are, the fmaller the Jhot will be; and the brim is to be thicker then thebottom,to conferve the heat the better.
The bottom of the Trencher being fome four inches diftant fr urn the water in the Pail,lay upon it fome burning Coles,to keep the Lead melt- ed upon it. Then with the hot Ladle take Lead of the Pot where it flands melted, and pour it foftly upon the burning Coles over the bottom of the Trencher, and it will immediately run through the holes into the water in fmall round drops. ThuA pour on new Lead fill as faji as it runs through the Trencher till all be done ; blowing now and then the Coles with hand-Bellows, when the Lead in the Trencher cools fo as to flop from running.
Whilfi one pours on the Lead, another mufti with another Lddle, tbruftedfour or five inches under water in the Pail, catch from time to time fome of the fhot,as it drops down, to fee the fize of it, and whether there be any faults in it. The gfeateft cafe is to keep the Lead upon the Trencher in the right degree of heat ; if it be too coot , it will not run through the Trencher, though it fiand melted upon it ; and this k to
24 MlCROGRAPHIA.
be helped by blowing the Coals a little , or pouring on new Lead that h hotter : but the cooler the Lead,the larger the Shot; and the hotter, the fmaller ; when it h too hot, the drops will crack, and fly ; then you mujl flop pouring on new Lead,andlet it cool; and fo long as you ob- ferve the right temper of the heat, the Lead will confiantly drop into very round Shot, without fo much as one with a tail in many pounds.
When all is done, take your Shot out of the Pail of water, and put it in a Frying-pan over the fire to dry them , which mufl be done warily, fiill jhakjng them that they melt not ; and when they are dry you may feparate the fmall from the great , in Pearl Sives made of Copper or Lattin let into one another, into as many fixes as you pleafe. But if you would have your Shot larger then the Trencher makes them , you may do it with a Sticky making them trickle out of the Ladle, as hath been faid.
If theTrencher be but toucht a very little when the Lead flops from going through it, and be not too cooljt will drop again , but it h better not to touch it at all. At the melting of the Lead take care that there be no kind of Oyl, Greafe, or the like, upon the Pots, or Ladles,or Tren- cher.
The Chief caufe of thh Globular Figure of the Shot, feems to be the Auripigmentum ; for, as foon as it it put in among the melted Lead, it hfes its finning brightnefs , controlling inflantly a grayifh film or skin upon it, when you fcum it to make it clean with the Ladle. So that whenthe Air comes at the falling drop of the. melted Lead, that skin confirms them every where equally : but upon what account, and whether thh be the true caufe, 'vs left to further difquifition,
Much after this fame manner, when the Air is exceeding cold through which it pafles., do we Hnd the drops of Rain, falling from the Clouds9 congealed into round Hail-ftonesby the freezing Ambient.
To which may be added this other known Experiment, That if you gently let fall a drop of water upon fmall find or dujly you fliall find, as it were, an artificial round Jione quickly generated. I cannot upon this oc- cafioti omit the mentioning of the ftrange kind of Grain , which I have obferved in a Jione brought from Kettering in Horth<iu:ftonJlme.;md there- fore called by Maibns Kettering- is tone 2, dj\fhicnTee the Defcription.
Which
Micrograph! A;
Which brings into my mind what I long fince obfervcd in the fiery Sparks that are ftruck out of a Steel. For having a great delire to fee what was left behind, after the Spark was gone out, I purpofely ftruck fire over a very white piece of Paper, and obferving diligently where fome confpi- cuous fparks went out , I found a very little black fpot no bigger then the point of a Pin, which through a Jllicrofcope appeared to be a perfect- ly round Ball, looking much like a polifht ball of Stdel, infomuch that I was able to fee the Image of the window reflected from it. I cannot hereftay ( having done it more fully in another place ) to examine the particular Reafons of it, but {ball only hint, that I imagine it to be fome imall parcel of the Steel , which by the violence of the motion of the ftroke ( moft of which feems to be impreft upon thofe fmall parcels ) is made fo glowing hot, that it is melted into a Vitrum, which by the ambi- ent Air is thruft into the form of a Ball.
A Fifth thing which I thought worth Examination was. Whether the motion of all kind of Springs, might not be reduced to the Principle whereby the included heterogeneous fluid feems to be moved 5 or to that whereby two Solids, as Marbles, or the like,are thruft and kept together by the ambient fluid.
A Sixth thing was,Whetner the Rifing and Ebullition of the Water out of Springs and Fountains ( which lie much higher from the Center of the Earth then the Superficies of the Sea, from whence it feems to be derived) may not be explicated by the rifing of Water in a fmaller Pipe .• For the Sea-water being ftrained through the Pores or Crannies of the Earth, is,- as it were, included in little Pipes, where the prefliire of the Air has not fo great a power to refift its rifing : But examining this way, and finding in it feveral difficulties almoft irremovable, I thought upon away that would much more naturally and conceivably explain it, which was by this following Experiment : I took a Glafs-Tube , of the form of that defcribed in the fixth Figure, and chufing two heterogeneous fluids , fiich as Water and Oyl , I poured in as much Water as filled up the Pipes as high as A B, then putting in fome Oyl into the Tube A G, I depreft the fuperficies A of the Water to E, and B I railed to G, which was not 1q high perpendicularly as the fuperficies of the Oyl F, by the fpace F I5 wherefore the proportion of the gravity of thefe two Liquors was as GHtoFE.
This Experiment I tried with feveral other Liquors , and particularly with frefh Water and Salt ( which I made by drflolving Salt in warm Water ) which two though they are nothing heterogeneous, yet before they would perfedly mix one with another, I made trial of the Experi- ment .• Nay, letting the Tube wherein I tried the Experiment remain for many dayes , I obferved them not to mix 5 but the fuperficies of the frefti was rather more then lefs elevated above that of the Salt. Now the proportion of the gravity of Sea- water, to that of River- water, accord- ing to Stevinus and Varenius , and as I have fince found pretty true by making trial my felf, is as 46. 1045. that is, 46. Ounces of the (alt Wa-
F ter
MlCROGRAPHIA.
ter will take up no more room then 45. of the frefh. Or reciprocally 45 pints of falt-water weigh as much as 46 of frefh.
But I found the proportion of Brine to frefh Water to be near 13 to 1 2: Suppofing therefore G H M to reprefent the Sea, and F I the height of the Mountain above the Superficies of the Sea , F M a Cavern in the Earth, beginning at the bottom of the Sea, and terminated at the top of the Mountain, L M the Sand at the bottom , through which the Water is as it were (trained , fb as that the frefher parts are only permitted to tranfude,and the faline kept back 5 if therefore the proportion of G M to F M be as 45 to 46, then may the Cylinder of Salt-water G M make the Cylinder of Frefh-water to rife as high as E, and to run over at N. I cannot here ftand to examine or confute their Opinion , who make the depth of the Sea, below its Superficies , to be no more perpendicularly meafured then the height of the Mountains above it : Tis enough for me to fay, there is no one of thofe that have aflerted it , have experimen- tally known the perpendicular of either 5 nor (hall I here determine,whe- ther there may not be many other caufes of the feparation of the frefh water from the fait , as perhaps fome parts of the Earth through which it is to pafs , may contain a Salt , that mixing and uniting with the Sea-falty may precipitate it 5 much after the fame manner as the Al^alizate and Acid Salts mix and precipitate each other in the preparation of Tarta- rnm Vitriolatum. I know not alfo whether the exceeding cold (that muft neceflarily be ) at the bottom of the Water, may not help towards this feparation , for we find , that warm Water is able to diflolve and contain more Salt , then the fame cold 5 infomuch that Brines ftrongly impregnated by heat, if let cool , do fuffer much of their Salt to fubfide and cryftallize about the bottom and fides. I know not alfb whether the exceeding prefliire of the parts of the Water one againft another, may not keep the Salt from defcending to the very bottom , as finding little or no rcom to infert it felf between thofe parts 9 protruded fb vio- lently together , or elle fqueeze it upwads into the fuperiour parts of the Sea, where it may more eafily obtain room for it felf, amongft the parts of the Water , by reafon that there is more heat and lefs prefmre. To this Opinion I was fbmewhat the more induced by the relations I have met with in Geographical 'Writers^ of drawing frefh Water from the bot- tom of the Sea , which is fait above. I cannot now ftand to examine, whether this natural perpetual motion may not artificially be imitated : Nor can I ftand to anfwer the Objections which may be made againft this my Suppofition : As, Firft, How it comes to pafs,that there arc fometimes fait Springs much higher then the Superficies of the Water? And, Se- condly ,Why Springs do not run fairer and flower, according to the vary- ing height made of the Cylinder of Sea- water, by the ebbing and flow- ing of the Sea }
As to the Firft, In fhort, I fay, the frefh Water may receive again a faline Tincture near the Superficies of the Earth , by pafling through fome fait Mines , or elfe many of the faline parts of the Sea may be kept back, though not all.
And
Micrographi a.
And as to the Second , The fame Spring may be fed and fupplyed by divers Caverns, coming from very far diftant parts of the Sea , fo as that it may in one place be high , in ahother lorv water and fo by that means the Spring may be equally iupply'd at all times. Or elfe the Cavern may be fo ftraight and narrow , that the water not having fo ready and free paiiage through it, cannot upon lo fhort and quick mutations of preflirre, be able to produce any fenfible eflbcT: at fueh a diftahec. Befides that, to confirm this hypothecs, there are many Examples found in Natural Hijio- rianspi Springs that do ebb and flow like the Sea : As particularly,thofe recorded by the Learned Camden, and after him by to be found in. this I/land: One of which,they relate to be on the Top of a Mountain, by the fmall Village Kilken in Flintfiire , Maris aemulus qui ftatis tempo- ribus fuasevomit & reforbct Aquas 5 Which at certain times rifeth and falleth after the manner of the Sea. A Second in Caermardenjhire, near Caermarden, at a place called Cantred Bichan 5 §>ui ( ut fcribit Gi- raldus ) natural/ die bis undis deficiens , & toties exuberans , marinas imitatur injiabilitates } That twice in four and twenty hours ebbing and flowing s reiembleth the unftable motions of the Sea. The Phenomena of which two may be eafily made out, by fuppofing the Cavern, by which they are fed, to arife from the bottom of the next Sea. A Third, is a Well upon the River Ogmore mGlamorganJlme, and near unto Newton, of which Camden relates himfelf to be certified5by a Letter from a Learned Friend of his that obferved it, t ons abeji hinc, &c. The Letter is a little too long to be inierted,but the fubftance is this 5 That this Well ebbs and flows quite contrary to the flowing and ebbing of the Sea in thole parts: for 'tis almoft empty at Full Sea, but full at Low water. This may hap- pen from the Channel by which it is fupplied , which may come from the bottom of a Sea very remote from thofe parts , and where the Tides are! much differing from thofe of the approximate (hores. A Fourth, lies in Wejlmorland, near the River Loder } Qui injiar Euripi fapius in die red- procantibus undis fluit & refluit , which ebbs and flows many times a day; This may proceed from its being fupplyed from many Channels , coming from feveral parts of the Sea, lying fufhciently diftant afunder to have the times of High-water differing enough one from the other 5 fo as that whenfoever it (hall be High water over any of thofe places, where thele . Channels begin, it ftiall likewife be fo in the Well 5 but this is but a luppo- fition.
A Seventh Query wa3. Whether the dijjolution or mixing of feveral bo- dies, whether tiuid or folid,with (aline or other Liquors,might not partly be attributed to this Principle of the congruity of thofe bodies and their dillolvents ? As of Salt in Water,Metals in feveral Menjiruums, Unduous Gums in Oyls, the mixing of Wine and Water, &c. And whether preci- pitation be not partly made from the fame Principle of Incongruity } I fay partly, becaule there are in fome Diildlutions,fome other Caufes con- current.
I (hall laftly make a much more feemingly ftrange and utiiikeij Query $ and that is, Whether this Principle, well examined and explained, may
F 2 not
MlCROGRAPHIA.
not be found a co-efficient in the moft confiderable Operations of Na- ture ? As in thofe of Heat^nd Lighted confequently.of Rarefaction and Condenfationi Hardnefi, and Fluidnefs, Perfpicuity and Opacoufnefs^Refr acti- ons and Colours. &c. Nay,I know not whether there may be many things done in Nature,in which this may not ( be faid to ) have a Finger ? This I have in fome other paflages of this Treatife further enquired into and Ihewn, that as well Light as Heat may be caufed by corrofton3which is ap- plicable to congruity^nd confequently all the reft will be but fubfequents: In the mean time I would not willingly be guilty of that £m>r,which the thrice Noble and Learned Verulam juftly takes notice of, as fuch,and calls Thilojophi£ Genus Empiricum , qnodinpaucorum Experimentoriun Anguftifr & Obfcuritate fundatum eji. For I neither conclude from one fingle Expe- rimemyior are the Experiments I make ufe of all made upon one Subject : Nor wreft I any Experiment to make it quadrarc with any preconceiv'd Notion. But on the contrary , I endeavour to be conversant in divers kinds of Experiments, and all and every one of thofe Trials, I make the Standards or Touchftones, by which I try all my former Notions, whether they hold out in weight, and meafure,and touch, &c For as that Body is no other then a Counterfeit Gold , which wants any one of the Proprie-1 ties of Cold, ( fuch as are the Malleablenels, Weight, Colour, Fixtnefs in the Fire,Indiflblublenels in Aqua fortis^nd the like ) though it has all the other j fo will all thofe Notions be found to be falfe and deceitful, that will not undergo all the Trials and lefts made of them by Experi- ments. And therefore fuch as will not come up to the defired Apex of Perfection , I rather wholly reject, and take new , then by piecing and patching,endeavour to retain the old,as knowing fuch things at beft to be but lame and imperfect. And this courfe I learned from Nature 5 whom we find neglectful of the old Body, and fuflering its Decaies and Infirmi- ties to remain without repair 3 and altogether follicitous and careful of perpetuating the Species by new Individuals. And it is certainly the moft likely way to erect a glorious Structure and Temple to Nature, fuch as (lie Will be found ( by any zealous Votary ) to refide in 5 to begin to build a new upon a fare Foundation of Experiments.
- But to digrels no .further from the confederation of the Th&nomena^ more immediately explicable by this Experiment, we (hall proceed to (hew, That, as to the rifing of Water in a Fibre, the reafon of it will be manifeft to him,that does take notice,that a Fibre is conftituted of a great number of fmall long fol d bodies , which lie fo clofe together, that the Air in its getting in between them , doth lofe of its preflure that it has a- gainftthe Fluid without them^ by which means the Water or Liquor not finding fo ftrong a reflftance between them as is able to counter-ballance the preflure on its fuperficies without, is raifed upward, till it meet with a prerture of the Air which is able to hinder it. And as to the Rifing of OyJ, melted Tallow, Spirit of Wine, &c. in the Week of a Candle or Lamp, it is evident, that it differs in nothing from the former, fa ve only in this, that in a Fibre the Liquor defcends and runs away by another part 3 and in the Week the Liquor is difperfed and carried away by the
...... • Flame j
.Micrograph! a. -
Flame > fomcthing there is aferibable to the Heat , for that it may rarifie the more volatil and fpirituous parts of thole combuftible Liquors, and fo being made lighter then the Air , it may be protruded upwards by that more ponderous fluid body in the Form of Vapours J but t.his can be afcribed to the afcenfion of but a very little,and moft likely of that on- ly which afcends without the Week. As for thefVifing of it in a Spunge, BreadjCotton.dv. above the llipci ficies of the fubjacent Liquor , what has been faid about the FJlfre ( if confidered) will eadly fuggeft a reafon , conlidering that all thefe bodies abound with final 1 holes or pores. ' • . r
From this fame Principle alio ( viz,, the unequal prejfttre of the Air a- gainfl the unequal Juperficies of the water ) proceeds the caufc oi the ac- ceflion orincurfion of any floating body againft the fides of the con- taining Veflel , or the appropinquatwn of two floating bodies, as Bubbles t Corks, Sticks, Straws^ &c. one towards another. As for inftance, Take a Glafs-jar, fuch as A B in the feventh Figure, and filling it pretty near the top with water , throw into it a fmall round piece of Cork , as C, and plunge it all over in water , that it be wet , fo as that the water may rife up by the fides of it,then placing it any where upon the fuperficies, about an inch,or one inch and a quarter from any fide, and you fhall perceive it by degrees to make perpendicularly toward the neareft part of the fide, and the nearer it approaches , the fatter to be moved $ the reafon of which Phenomenon will be found no other then this , that the Air has a greater prefliire againft the middle of th.Q fuperficies , then it has againir thofe parts that approach nearer , and are contiguous to the fides. Now that the prefliire is greater , may ( as I (hewed before in the explication of the third Figure ) be evinced from the flatting of the water in the middle, which ariles from the gravity of the under fluid : for fince, as I (hewed before,if there were no gravity in the under fluid,or that it were equal to that of the upper , the terminating Surface would be Spherical, and fince it is the additional prefliire of the gravity of water that makes it fo flat,it follows, that the prefliire upon the middle muft be greater then towards the fides. Hence the Ball having a ftronger prefliire againft that fide of it which refpecrs the middle of the Juperficies , then againft that which rerpedfs the approximate fide . muft neceflarily move towards that part, from whence it finds leaft refiftance, and fo be accelerated, as the re- fiftance decreafes. Hence the more the water is railed under that part of its way it is palling above the middle, the fafter it is moved : And therefore you will find it to move fafter in E then in D, and in D then in C. Neither could I find the floating fubftance to be moved at all, un- til it were placed upon fome part of the Superficies that was fenhbly ele- vated above the height of the middle part. Now that this may be the true caufe, you may try with a blown Bladder, and an exadly round Ball upon a very imooth fide of fome pliable body , as Horn or Quicksilver. For if the Ball be placed under a part of the Bladder which is upon one fide of the middle of its prefliire , and you preis ftrongly againft the Bladder,you ihall find the Ball moved from the middle towards the fides.
Having
Mi CROGRAPHIA.
Having therefore fhewn the reafon of the motion of any float towards the fides, the reafon of the incurfion of any two floating bodies will eafi- ly appear : For the rifing of the water againft the fides of either of them,is an Argument fufticient,to fliew the prellure of the Air to be there lefsjthen it is further from it,where it is not fo much elevated $ and there- fore the realbn of the motion of the other toward it , will be the fame as towards the fide of the Glafs only here from the lame reafon , they are mutually moved toward each other , whereas the fide of the Glafs in the former remains fixt. If alfo you gently fill the Jar fo full with water3 that the water '^protuberant above the fides, the fame piece of Cork that before did haften towards the fides , does now fly from it as faft towards the middle of the Superficies j the realbn of which will be found noo- ther then this, that the prelTure of the Air is fironger againft the fides of the Superficies G and H, then againft the middle 1 5 for fince, as I (hewed
Spherical , and that the flatting of the Surface in the middle is from the abatement of the waters prefliire outwards, by the contrary indeavour of its gravity 5 it follows that the prefliire in the middle muft be lefs then on the fides } and therefore the confecution will be the fame as in the former. It is very odd to one that considers not the reafon of it , to fee two floating bodies of wood to approach each other,as though they were indued with fome magnetical vigour , which brings into my mind what I formerly tried with a piece of Cork or fuch like body, which I fo order- ed, that by putting a little (tick into the fame water, one part of the faid Cork would approach and make toward the ftick, whereas another would dilcede and fly away,nay it would have a kind of verticity , fo as that if the Equator ( as I may fo fpeak ) cf the Cork were placed to* wards the ftick, if let alone, it would inftantly turn its appropriate Pole toward it, and then run a-tilt at itrand this was done only by taking a dry Cork, and wetting one fide of it with one fmall ftroak 5 for by this means gently putting it upon the water, it would deprefs the fuperficies on eve- ry fide of it that was dry , and therefore the greateft prefliire of the Air, being near thofe fides caufed it either to chafe away,or elfe to fly oft from any other floating body, whereas that fide only, againft which the water alcended,Avas thereby able to attracl.
It remains only, that I lhould determine how high the Water or other Liquor may by this means be raifed in a fmaller Pipe above the Superfi- cies of that without it , and at what height it may be fuftained : But to determine this, will be exceeding difficult, unlefs I could certainly know how much of the Airs prefiure is taken oft' by the fmalnefs of fuch and fuch a Pipe,and whether it may be wholly taken orT,that is,whether there can be a hole or pore fo fmall , into which Air could not at all enter, though water might with its whole force ^ for were there foch , 'tis mani- feft , that the water might rile in it to fome five or fix and thirty Englifti Foot high. I know not whether the capillary Pipes in the bodies of fmall Trees, which we call their JUicrojcopical pores. jenzy not be fuch 5 and whe- ther the congruity of the fides of the Pore may not yet draw the juyce
before, the Principle of
would make the terminating Surface
even
MlCROGRAPHlA.
even higher then the Air was able by its bare prcflurc toraifcit: For, Congruity is a principle that not only unites and holds a body joyned to it, but, which is more, attracts and draws a body that is very near it, and holds it above its ufiial height.
And this is obvious even in a drop of water fufpended under any Si- milar or Congruous body : For,befides the ambient preiiiire that helps to keep it fulteind, there is the Congruity of the bodies that are contigu- ous. This is yet more evident in Tenacious and Glutinous bodies 5 fuch as Gummous Liquors, Syrups, Pitch, and Rofin melted^ &c. Tar, Tur- pentine, Balfbm, Bird-lime, &c. for there it is evident, that the Parts of the tenacious bod}', as I may fo call it, do (tick and adhere lb clofe- ly together, that though drawn out into long and very (lender Cylin- ders, yet they will not eafily relinquilh one another ? and this, though the bodies be aliquatenus fluid, and in motion by one another 5 which, to fuch as confider a fluid body only as its parts are in a confuted irregu- lar motion, without taking in alio the congruity of the parts one among another, and incongruity to (bme other bodies, does appear not alittle Orange. So that befides the incongruity of the ambient fluid to it, we are to confider alfo the congruity of the parts of the contein d fluid one with another.
And this Congruity ("that I rnay here a little further explain it ) is both a Tenaceous and an Attractive power 5 for the Congruity, in the Vi- brative motions,may be the caufeof all kind of attraction, not only Ele- ctrical, but Magnetical alfo, and therefore it may be alfo of Tenacity and Glutinoufnefs. For, from a perfect congruity of the motions of two diftant bodies, the intermediate fluid particles are feparated and dro- ven away from between them, and thereby thofe congruous bodies are, by the incompafling mediums, compell'd and forced neerer together 3 wherefore that attradtivenefs muft needs be ftronger, when, by an im- mediate contact, they are fore'd to be exactly the lame : As I (hew more at large in my 'Theory of the Magnet. And this hints to me the realbn of the fufpenfion of the Mercury many inches, nay many feet, above the ufii- al (ration of 30 inches. For the parts of gmickrfilver, being (b very fimilar and congruous to each other, if once united, will not eafily (uffer a divulfion : And the parts of water, that were any wayes heterogeneous^ being by exantlation or rarefaction exhauft ed, the remaining parts being alfo very fimilar, will not eafily part neither. And the parts of the Glate being folid, are more difficultly disjoyn ct 3 and the water, being fome- what fimilar to both, is, as it were, a medium to unite both the Clafi and the Mercury together. So that all three being united, and not very dip fimilar, by means of this contact, if care be taken that the Tube in e- recting be not (hogged, the Quicksilver will remain fufpended, notwith- ftanding its contrary indeavour of Gravity , a great height above its or- dinary Station , but if this immediate Contact be removed , either by a meer feparation of them one from another by the force of a (hog, where- by the other becomes imbodied between them, and licks up from the furface fome agil parts , and fo hurling them makes them air 3 or elie
MiCROGRAPHIA.
byfome fmall heterogeneous agil part of the Water, or Air, orQuick- fiJver, which appears like a bubble, and by its jumbling to and fro there is made way for the heterogeneous JEthcr to obtrude it felf between the Glafs and either of the other Fluids, the Gravity of Mercury precipitates it downward with very great violence $ and if the Veflel that holds the reftagnating Mercury be convenient, the Mercury will for a time vibrate to and fro with very large reciprocations^ and at laft will remain kept up by the preflure of the external Air at the height of neer thirty inches. And whereas It may be objected, that it cannot be, that the meer imbodying of the jEther between thefe bodies can be the caufe,fince the JEther ha- ving a free paffage alwayes , both through the Pores of the Glals , and through thole of the Fluids , there is no reafon why it (hould not-make a feparation at all times whilft it remains fufpended, as when it is violently difjoyned by a fhog. To this I anfwer , That though the JEther pafles between the Particles, that is, through the Pores of bodies, fo as that any chafme or feparation being made , it has infinite pallages to admit its en- try into it, yet fuch is the tenacity or attractive virtue of Congruity, that till it be overcome by the meer ftrength of Gravity, or by a fhog afiifting that Conatus of Gravity, or by an agil Particle, that is like a leaver agi- tated by the Mtber 3 and thereby the parts of the congruous fubftances are feparated fo far afunder , that the ftrength of congruity is fo far wea- kened^ not to be able to reunite them, the parts to be taken hold of be- ing removed out of the attractive Sphere, as I may fo fpeak, of the con- gruity 5 fuch, I fay, is the tenacity of congruity, that it retains and holds the almoft contiguous Particles of the Fluid , and fuffers them not to be feparated, till by meer force that attractive or retentive faculty be over- come : But the feparation being once made beyond the Sphere of the attractive activity of congruity , that virtue becomes of no effect at all, but the Mercury freely falls downwards till it meet with a refiftance from the preflure of the ambient Air, able to refift its gravity, and keep it for- ced up in the Pipe to the height of about thirty inches.
Thus have I gently raifed a Steel pendulumhy aLoadftone to a great Angle^till by the fhaking of my hand I have chanced to make a fepara- tion between them, which is no fooner made, but as if the Loadftone had retained no attractive virtue, the Pendulum moves freely from it towards the other fide. So vafta difference is there between the attractive vir- tue of the Magnet when it acts upon a contiguous and upon a disjoyned body : and much more muft there be between the attractive virtues of congruity upon a contiguous and disjoyned body 5 and in truth the attra- ctive virtue is fb little upon a body disjoyned, that though I have with a Micro/cope obferved very diligently, whether there were any extraordi- nary protuberance on the fide of a drop of water that was exceeding neer to the end of a green ftick, but did not touch it, I could not perceive the leaft} though I found, that as foon as ever ittoncht it the whole drop would prefently unite it felf with it 3 fo that it feems an abfolute con- tact is requifite to the exercifing of the tenacious faculty of congruity.
Obferr.
Micrograph! a.
'fno
— - — -
Obferv. VII. Of fome Phenomena of Glafs drops.
Iff? 9f.<nli ol gr/;/ ToaJGifi bmn u j. orii 13^ lua ::>iiiKjTnt a<rid (rtJiq b bnut
THefeC?/*/} Drops are fmall (parcels of coarlc green Glafe taken out of the Pots that contain the Metal fas they call it Q in fufion, upon the end of an Iron Pipe 5 and being exceeding hot, and thereby of a kind of fluggifh fluid Confidence, are (uttered to drop from thence into a Bucket of cold Water, and in it to lye till they be grown fenfibly cold.
Some of thcfe I broke in the open air , by mapping ofFa little of the1 fmall ftem with my fingers, others by crulhing it with a (mall pair of Ply- ers 3 which I had no (boner done 3 then the whole bulk of the drop flew violently, with a very brisk noife, into multitudes of fmall pieces, fome of which were as fmall as duft, though in fome there were remaining pieces pretty large, without any flaw at all,and others very much flaw'd, which by rubbing between ones fingers was eafily reduced to duft $ thefe di- (perfed every way fo violently , that fome of them pierced my skin, t could not find,either with my naked Eye,or a Microfcope, that any of the broken pieces were of a regular figure,nor any one like another, but for the moft part thofe that flaw'd off in large pieces were prettily bran- ched.
The ends of others of thefe drops Fnipt off whilft all the bodies and ends of them lay buried under the water, which, like the former, flew alt to pieces with as brisk a noife, and as ftrong a motion.
Others of thefe I tried to break, by grinding away the blunt end, and though I took a feemingly good one , and had ground away neer two thirds of the Ball, yet would it not fly to pieces, but now and then fome fmall rings of it would fnap and fly off, not without a brisk none and quick motion,leaving the Surface of the drop whence it flew very pretti- ly branched or created , which was eafily diicoverable by the Micro/cope. This drop,after I had thus ground it, without at all impairing the remnant that was not ground away, I cawed to fly immediately all into (and upon the nipping off the very tip of its (lender end.
Another of thefe drops I began to grind away at the (mailer end , but had not worn away on the ftone above a quarter of an inch before the whole drop flew with a brisk crack into fand or fmall duft 3 nor would it have held fo long , had there not been a little flaw in the piece that I ground away, as I afterwards found.
Several others of thefe drops I covered over with a thin but very tuff skin of Icthyocolla^ which being very tough and very tranfparent,Was the moft convenient fubftance for thefe tryals that I could imagine, having dipt,I fay. feveral of thefe drops in this tranfparcnt Glue whilft hot , and differing them to hang by a ftring tied about the end of them till they were cold, and the skin pretty tough 5 then wrapping all the body of the
G drop
Micrograph i a.
drop ( leaving out only the very tip ) in fine fupple Kids-leather very clofely,l nipped orTthe fmall top, and found, as I expected, that notwith- ftanding this skin of Glue , and the clofe wrapping up in Leather , upon the breaking of the top, the drop gave a crack like the reft, and gave my hand a pretty brisk impulfe: but yet the skin and leather was fo ftrong as to keep the parts from flying out of their former pofture} and, the skin being tranfparent , I found that the drop retained exactly its former fi- gure and polilh, but was grown perfectly opacous and all over flaw'd, all thofe flaws lying in the manner of rings, from the bottom or blunt end, to the very top or fmall point. And by feveral examinations with a Micro* Jcope} of feveral thus broken, I found the flaws, both within the body of the drop, and on the outward furface,to lye much in this order.
Let A B in the Figure X of the fourth Scheme reprefent the drop cafed over with Itthyocolla or ifinglafs^nd f by being ordered as is before pre- ' fcribed ) crazed or flawed into pieces, but by the skin or cafe kept in its former figure , and each of its flawed parts preferved exactly in its due pofture 5 the outward appearance of it fbmcwhat plainly to the naked eye, but much more conspicuous if viewed with a fmall fenfi appeared much after this fhape. That is, the blunt endB for a pretty breadth, namely , as far as the Ring C C C feemed irregularly flawed with divers clefts, which all feemed to tend towards the Center of it, being, as I af- terwards found , andfhall anon (hew in the defcription of the figure Y, the Bafis, as it were, of a Cone, which was terminated a little above the middle of the drop , all the reft of the Surface from C C Q to A was flawed with an infinite number of fmall and parallel Rings, which as they were for the moft part very round , fb were they very thick and clofe together, but were not fo exactly flaw'd as to make a perfect Ring , but each circular part was by irregular cracks flawed likewife into multitudes of irregular flakes or tiles 3 and this order was obferved likewife the whole length of the neck.
Now though I could not fb exactly cut this conical Body through the Axis, as is reprefented by the figure Y , yet by anatomizing, as it were, of feveral, and taking notice of divers particular circumftances, I was in- formed, that could I have artificially divided a flaw'd drop through the Axis or Center . I fhould with a Microfcope have found it to appear much of this form , where A fignifies the Apex , and B the blunt end, C C the Cone of the Bafis, which is terminated at T the top or end of it , which feems to be the very middle of the blunt end, in which, not only the co- nical body of the Bafis C C is terminated, but as many of the parts of the drop as reach as high as D D.
And it feemed to be the head or beginning of a Pith, as it were, or a a part of the body which feemed more fpungy then the reft, and much more irregularly flawed, which from T afcended by E E, though lefs vi- fible, into the fmall neck towards A. The Grain, as it were, of all the flaws , that from all the outward Surface A DC C D A, was much the fame,as is reprefented by the black ftrokes that meet in the middleDT, DT, DE,D E, &c.
Not
M I C ROG R A P H I A*
Nor is this kind of Grain , as I may call it, peculiar to Glafs drops thus quenched 5 for Cnot to mention Coper as-ftones , and divers other Mar- chajites and Minerals , which I have often taken notice of to be in the very fame manner flaked or grained, with a kind of Pith in the middle ) I have oblerved the fame in all manner of caft Iron , cfpecially thecoar- fer fort, fuchas Stoves, and Furnaces, and Backs, and Pots are made of ; For upon the breaking of any of thofe Subftances it is obvious to ob- ferve, how from the out-fides towards the middle, there is a kind of Radiation or Grain much refembling this of the Glafs-drop; but this Grain is moft confpicuous in Iron-bullets , if they be broken : the fame Phenomena mav be produced by cafting regulus of Antimony into a Bullet-mold, as alfo with Glafs of Antimony , or with almoft any fuch kind of 'Vitrified fubfancc , either caft into a cold Mold or poured into Water.
Others of thefe Drops I heat red hot in the flrc,and then differed them to cool by degrees. And thefe I found to have quite loft all their fnlmi- nating or flying quality, as alfo their hard, brittle and fpringy texture 5 and to emerge of a much fofter temper, and much eafier to be broken or inapt with ones finger-but its ftrong and brittle quality was quite deftroy- ed, and it feemed much of the fame confidence with other green Glafs well nealed in the Oven.
The Figure and bignefsof thefe for the moft part was the fame with that of the Figure Z 5 that is,all the furface of them was very fmooth and polifht,and for the moft part round , but very rugged or knobbed about D, and all the length of the ftem was here and there pitted or flatted. About D, which is at the upper part of the drop under that fide of the ftem which is concave , th*ere ufually was made fome one or more little Hillocks or Prominences. The drop it felf, before it be broken, appears very tranfparent , and towards the middle of it, to be very full of fmall Bubbles, of fbme kind of aerial fubftance, which by the refraction of the outward furface appear much bigger then really they are 5 and this may be in good part removed, by putting the drop under the furface of clear Water, for by that means moft part of the refraction of the convex Sur- face of the drop is deftroyed , and the bubbles will appear much fmaller. And this, by the by. minds me of the appearing magnitude of the aper- ture of the iris, or pupil of the eye, which though it appear5 and be there- fore judged very large , is yet not above a quarter of the bignefs it ap-* pears of, by the lenticular refraction of the Cornea.
The caufe of all which Thanomena I imagine to be no other then this, That the Parts of the Glafs being by the excefftve heat of the fire kept off and feparated one from another, and thereby put into a kind of flug- gifh fluid confiftence , are differed to drop off with that heat or agitation remaining in them, into cold Water 5 by which means the outfides of the drop are prefently cool'd and crafted , and are thereby made of a loofe texture,becaufe the parts of it have not time to fettle themfelves leifurely together , and fb to lie very clofe together : And the innermoft parts of the drop, retaining ftill much of their former heat and agitations, remain
G 2 of
MlCROGRAPHIA*
of a loofe texture alfo,and,according as the cold ftrikes inwards from the bottom and fides, are quenched, as it were, and made rigid in that very pofture wherein the cold finds them. For the parts of them//? being already hardened , will not fuffer the parts to fhrink any more from the outward Surface inward 5 and though it (brink a little by reafonof the fmall parcels of fome Aerial fubftances difperled thr6ugh the matter of the Glaft, yet that is not neer fo much as it appears ( as I juft now hint- ed jj nor if it were, would it be fufficient for to confolidate and condenfe the body of Glafs into a tuff and dole texture , after it had been fo ex- ceflively rarified by the heat of the glafs-Furnace.
But that there may be (ixh an expanfion of the aerial fubftance con- tained in thofe little blebbs or bubbles in the body of the drop , this fol- lowing Experiment will make more evident.
Take a fmall Glaft-Cane about a foot long , feal up one end of it her- metically,then put in a very fmall bubble of Glafs, almoft of the fhape of an Eflence-viol with the open mouth towards the fealed end , then draw out the other end of the Pipe very fmall,and fill the whole Cylinder with water , then fet this Tube by the Fire till the Water begin to boyl , and the Air in the bubble be in good part rarified and driven out , thenby lucking at the fmalling Pipe, more of the Air or vapours in the bubble may be fuck'd out , fo that it may fink to the bottom 5 when it is funk to the bottom,in the flame of a Candle,or Lamp,nip up the (lender Pipe and let it cool : whereupon it is obvious to obferve, firft, that the Water by degrees will fubfide and (brink into much leis room : Next, that the Air or vapours in the Glafs will expand themfelves lb, as to buoy up the little Glafs : Thirdly, that all about the infide of tfte Glals-pipe there will ap- pear an infinite number of fmall bubbles, which as the Water grows colder and colder will fwell bigger and bigger, and many of them buoy them- felves up and break at the top.
From this Difceding of the heat in Glafs drops,that is, by the quenching or cooling Irradiations propagated from the Surface upwards and in- wards, by the lines C T, CT, DT, DE,^. the bubbles in the drop have room to expand themfelves a little, and the parts of the Glafs con- tract themfelves, but this operation being too quick for the (lug^ifh parts of the Glafs, the contraction is performed very unequally and irregularly, and thereby the Panicles of the Glals are bent, fome one way, and lome another, yet foas that moft of them draw towards the Pith or middle TEEE, or rather from that outward : fo that they cannot extricate ox unbend themfelves, till fome part of T E E E be broken and loofened, for all the parts about that are placed in the manner of an Arch, and fo till their hold at T EE E be loofened they cannot fly afunder, but up- hold, and (belter, and fix each other much like the Hones in a Vault, where each done does concurre to the frability of the whole Fabrick, and no one (tone can be taken away but the whole Arch falls. And wherc- foever any of thofe radiating wedges DT D^&c are removed, which are the component parts of this Arch,the whole Fabrick prefentlyfellsto
pieces :
MlCROGRAPHlA*
pieces^ for all the Springs of the feveral parts are fet at liberty, which immediately extricate themfelves and fly afunder every way > each part by its fpring contributing to the darting of it ielf and fome other contigu- ous part. But if this drop be heat lb hot As that the parts by degrees, can unbend themfelves, and be fettled and annealed in that pofture , and be then iiirTered gently tofubfide and cool; The parts by this nealing lo- fing their fpringinels , conftitute a drop of a more (oft but iefs brittle tex- ture,and the parts being not at all under a flexure, though any part of the middle or Pith TEE E be broken,yet will not the drop at all fly to pieces as before.
This Conjecture of mine I (hall indeavour to make out by explain- ing each particular Aflertion with analogous Experiments : The Allertion* aretheie.
Firft , That the parts of the Clafs , whilft in a fluid Confidence and hot , are more ranfied , or take up more room , then when hard and cold.
Secondly , That the parts of the drop do fuffer a twofold contra*1 cxion.
Thirdly, That the dropping or quenching the glowing metalin the Water makes it of a hard, fpringing, and rarified texture.
Fourthly , That there is a flexion or force remaining upon the parts of the Glafs thus quenched , from which they indeavour to extricate themfelves.
Fifthly, That the Fabrick of the drop: that is able to hinder the parts from extricating themfelves, is analogue to that of an Arch.
Sixthly, That the fudden flying afunder of the parts proceeds frosj their fpringinels.
Seventhly, That a gradual heating and cooling does anneal or reduce the parts of Glafs to a texture that is more loofe, andeahlier to be bro- ken, but not fo brittle.
That the firft of thefe is true may be gathered from this, That Beat is a property of a body arifing from the motion or agitation of its parts } and therefore whatever body is thereby toucht mult neceflarily receive fome part of that motion.whereby its parts will be (haken and agitated, and fo by degrees free and extricate themfelves from one another , and each part fo moved does by that motion exert a conatus of protruding and dip placing all the adjacent Particles. Thus Air included in a veflel, by be- ing heated will burft it to pieces. Thus have I broke a Bladder held over the fire in my hand, With fuch a violence and noife , thatkalmoft Kiade me deaf for the prefent,and much furpafled the noife of a' Musket: The like have I done by throwing into the fire fmaH glafs Bubbles her- jnetically fealed , with a little drop of Water included in them. Thus Water alfo,orany other Liquor, included in a convenient veilel,by being warmed, ma nifeftly expands it fclf with a very great violence , ibasttf break the ftrongeft vcflel, if when heated it be ria-rr.owly imprifoned in it.
This
Ml CROGRAP H1A.
This is very manifeft by the feakdJhermometers^ which I have, byfeve- ral tryals,at laft brought to a great certainty and tenderneis : for I have made feme with items above four foot long , in which the expanding Li- quor would fo far vary,as to be very neer the very top in the heat of Sum- mer, and prety neer the bottom at the coldeft time of the Winter. The Stems I ufe for them are very thick,ftraight,and even Pipes of Glafs,with a very fmall perforation , and both the head and body I have made on purpofe at the Glals-houfe , of the fame metal whereof the Pipes are drawn : thefe I can eafily in the flame of a Lamp, urged with the blaft of a pair of Bellows, feal and clofe together, fo as to remain very firm, clofe and even $ by this means I joyn on the body firft,and then fill both it and a part of the item , proportionate to the length of the ftem and the warmth of the feafbn I fill it in^with the beft rectified Spirit of Wine high- ly ting'd with the lovely colour of Cocheneel, which I deepen the more by pouring fome drops of common Spirit of Vrine , which muft not be too well rectified , becaufe it will be apt to make the Liquor to curdle andftick in the fmall perforation of the ftem. This Liquor I have upon tryal found the moft tender of any fpirituous Liquor,and thofe are much more fenfibly affected with the variations of heat and cold then other more flegmatick and ponderous Liquors, and as capable of receiving a deep tin&ure, and keeping it,as any Liquor whatfoever $ and ( which makes it yet more acceptable ) is not fubjeft to be frozen by any cold yet known. When I have thus filled it,I can very eafily in the foremention- ed flame of a Lamp leal and joyn on the head of it.
Then, for graduating the ftem, I fix that for the beginning of my di- vision where the furface of the liquor in the ftem remains when the ball is placed in common diftilled water, that is fo cold that it juft begins to freeze and fhoot into flakes 5 and that mark I fix at a convenient place of the ftem, to make it capable of exhibiting very many degrees of cold, below that which is requifite to freeze water : the reft of my divifions, both above and below this (which I mark with a [p] or nought J I place according to the Degrees of Expanfion0 or Contraiiion of the Liquor in proportion to the bulk it had when it indur'd the newly mentioned freez- ing cold. And this may be very eafily and accurately enough done by this following way 5 Prepare a Cylindrical veflel of very thin plate Brafs or Silver, A B C D of the figure Z 5 the Diameter A B of whofe cavity let be about two inches, and the depth B C the fame 3 let each end be cover'd with a flat and fmooth plate of the fame fubftance, clofely foder'd on, and in themidft of the upper cover make a pretty large hole E F, about the bignefs of a fifth part of the Diameter of the other 3 into this faften very well with cement a ftraight and even Cylindrical pipe of Glafs, E F G H, the Diameter of whofe cavity let be exactly one tenth of the Diameter of the greater Cylinder. Let this pipe be mark'd at G H with a Diamant, fo that G from E may be diftant juft two inches, or the fame height with that of the cavity of the greater Cylinder, then divide the length E G exactly into 10 parts, fo the capacity of the hollow of each of thele divifions will be part of the capacity of the greater Cylin-
MiCROGRAPHIA
der. This veflel being thus prepared, the way of marking and gradu- ating the Thermometers may be very eafily thus performed :
Fill this Cylindrical veflel with the lame liquor wherewith the Ther- mometers are fill'd, then place both it and the Thermometer you arc to graduate, in water that is ready to be frozen, and bring the furface of thfl liquor in the Thermometer to the hrft rnarke or [o]} then fo proportion the liquor in the Cylindrical veflel, that the furface of it may juft: be at the lower end of the fmall glafs-Cylinder $ then very gently and gradu- ally warm the water in which both the Thermometer and this Cylindrical veflel ftand, and as you perceive the ting'd liquor to rife in both items* with the point of a Diamond give feveral marks on the Item of the Ther* mometer at thofe places, which by comparing the expanfion in both Stems , are found to correfpond to the divifions of the cylindrical veflely and having by this means marked fome few of thefe divifions on the Stem, it will be very eafie by thefe to mark all the reft of the Stem, and accordingly to aflign to every divifion a proper character.
A Thermometer , thus marked and prepared, will be the fittcit Inftru- ment to make a Standard of heat and Cold that can be imagined. For1 being fealed up, it is not at all lubject. to variation or wafting, nor is it lia- ble to be changed by the varying preflure of the Air 3 which all other kind of Thermometers that are open to the Air are liable to. But to pro- ceed.
This property of Expanfion with Heat, and Contraction with Cold, is not peculiar to Liquors only, but to all kind of folid Bodies alio, efpeci- ally Metals, which will more manifeftly appear by this Experiment.
Take the Barrel of a Stopcock of Brafs, and let the Key, which is well fitted to it,be riveted into it,fo that it may Uip,and be eafily turned round, then heat this Cock in the fire, and you Will find the Key fo fwollen, that you will not be able to turn it round in the Barrel 5 but if it be fuffered to cool again, as fbon as it is cold it will be as movable, and as eafie to be turned as before.
This Quality is alfo very obfervable in Lead, Tin, Silver, Antimony 4 Pitch^Rofn^Bees-wax.Btitter^hd the like} all which,if after they be melted you fufler gently to cool , you (hall find the parts of the upper Surface to lubfide and fall inwards , lofing that plumpnefs and fmoothnefs it had whilft in fufion* The like I have alfo obferved in the cooling of Glafs of Antimony, which does very neer approach the nature of Glafs,.
But becaule thefe are all Examples taken from other materials then Gla(s,and argue only, that poflibly there may be the like property alfo in Glafs, not that really there is 5 we (hall by three or four Experiment* in-1 deavour to manifeft that alfo.
And theFirft is an Obfervation that is very obvious even in thefe very drops,to witjthat they are all of them terminated with an unequal or ir* regular Surface 5 elpecially about the (mailer part of the drop, and the whole length of the ftem \ as about D, and from thence to A, the whole Surface, which would have been round if the drop had cool'd leifiirely, if, by being quenched haitily,very irregularly flatted and pitted 9 which
40 Micrograph t a .
I fuppofe proceeds partly from the Waters unequally cooling and pref* fing the parts of the drop, and partly from the felt-contra&ing or fubfi- ding quality of the fubftance of the Glafs: For the vehemency of the heat of the drop caufcs fuch fudden motions and bubbles in the cold Wa- ter,that fome parts of the Water bear more forcibly againft one parr then againft another 3 and confequently do more fuddenly cool thofe parts to which they are contiguous.
A Second Argument may be drawn from the Experiment of cutting Clafles with a hot Iron. For in that Experiment the top of the Iron heats , and thereby rarities the parts of the Glafs that lie juft before the crack, whence each of thofe agitated parts indeavouring to expand its felf and get elbow-room, thrufts off all the reft of the contiguous partSj and confequently promotes the crack that was before begun.
A Third Argument may be drawn from the way of producing a crack in a found piece or plate of Glafi, which is done two wayes, either Firft, by fuddenly heating a piece of Glals in one place more then in another. And by this means Chymijls ufually cut off the necks of Glafs-bodies, by two kinds of Inftruments , either by a glowing hot round Iron-Ring, which juft incompafles the place that is to be cut , or elfe by a Sulphur d Threed:which is often wound about the place where the leparation is to be made,and then fired. Or Secondly .A Glafs may be cracked by cooling it fuddenly in any place with Water, or the like, after it has been all lei- furely and gradually heated very hot. Both which Phanomena feem ma- nifeftly to proceed from the expanfion and contra&ion of the parts of the Glafs , which is alfo made more probable by this circumftance which I have obferved , that a piece of common window-glafs being heated in the middle very fuddenly with a live Coal or hot Iron,does ufually at the firft crack fall into pieces,whereas if the Plate has been gradually heated very hot , and a drop of cold Water and the like be put on the mid- dle of it, it only flaws it, but does not break it afunder immedi- ately.
A Fourth Argument may be drawn from this Experiment $ Take a Glafs-pipe, and fit into it a folid ftick of Glafs, fb as it will but juft be mo- ved in it. Then by degrees heat them whilft they are one within ano- ther,and they will grow ftiffer, but when they are again cold,they will be as eafie to be turned as before. This Expanfion of Glafs is more mani- feft in this Experiment.
Take a ftick of Glafs of a confiderable length,and fit it fb between the two ends or fcrews of a Lath,that it may but juft eafily turn,and that the very ends of it may be juft touchtand fufteined thereby , then applying the flame of the Candle to the middle of it, and heating it hot, you will prefently find the Glafs to ftick very faft on thofe points, and not without much difficulty to be convertible on them , before that by removing the flame for a while from it, it be fuffered to cool, and en y ou will find it as ealie to be turned round as at the firft.
From all which Experiments it is very evident, that all thofe Bodies, and particularly Glafs, fuffers an Expanfion by Heat, and that a very con- fiderable
Ml CROGRAPHIA.
fiderable one,whilft they are in a ftate of Fufion. For FW//^3asIei(ewhere mention, being nothing but an effett of a very firong and quit kjhai<i»g motion^ whereby the parts arenas it were Joofened front each other ^and conjequently have an interjacent fpace or vacutty j it follows, that all thofe fhaken Particles muft neceflarily take up much more room then when they were at reft, and lay quietly upon each other. And this is further confirmed by a Pot of boyling Alabajter, which will manifeftly rife a fixth or eighth part higher in the Pot, whilftit is boyling, then it will remain at, both before and after it be boyl- ed.The reafon of which odd rh<enomenon ( to hint it here only by the way) is this , that there is in the curious powder of Alabafter, and other calcining Stones, a certain watery fubftance, which is fo fixt and included with the folid Particles, that till the heat be very confiderable they will not fly aways but after the heat is increafed to fuch a degree , they break out every way in vapours, and thereby fo (hake and loofen the miall corpufles of the Pow- der from each other, that they become perfectly of the nature of a fluid bo- dy, and one may move a ftick to and fro through it, and ftir it as eafily as water, and the vapours burft and break out in bubbles juftas in boyling water,and the like 5 whereas, both before thofe watery parts are flying away, and after they are quite gone j that is, before and d fter it have done boy ling,all thofe effects ceafe , and a ftick is as difficultly moved to and fro in it as in fand5 or the like. Which Explication I could eafily prove, had I time but this is not a fit place for it.
To proceed therefore, I lay,thatthe dropping of this expanded Body in- to cold Water, does make the parts of the Clafs fuffer a double contraction ; The firft is, of thofe parts which are neer the Surface of the Drop. For Cold, as I faid before,contracting Bodies, that is3by the abatement of the agitating fa- culty the parts fallingneerer together 3 the parts next ad joying to the Water muft needs lofe much of their motion , and impart it to the Ambient-water (which the Ebullition and commotion of it manifefts) and thereby become a folid and hard cruft, whilft the innermoft parts remain yet fluid and ex- panded J, whence,as they grow cold alfoby degrees,their parts muft necefla- rily be left at liberty to be condenled , but becaufeof the hardnefsof the outward cruft,the contraction cannot be admitted that way$but there being many very fmall, and before inconfpicuous, bubbles in the fubftance of the Glals,upon the fubfiding of the parts of the Glafs,the agil fubftance contain- ed in them has liberty of expanding it felfa little,and thereby thofe bubbles grow much bigger,which is the fecond Contraction^ And both thefe are con- firmed from the appearance of the Drop it felf : for as for the outward parts, we fee,firft,that it is irregular and Ihrunk, as it were, which is caufed by the yielding a little of the hardened Skin to a Contraction , after the very out- moft Surface is fettled j and as for the internal parts , one may with ones naked Eye perceive abundance of very confpicuous bubbles, and with the Microfcop* many more^
The Confideration of which Particulars will eafily make the Third Pofiti- on probable,that is,that the parts of the drop will be of a very hard, though of a rarified Texture 5 for if the outward parts of the Drop, by reafon of its hard cruft. will indure very little Contraction, and the agil Particles, inclu-
H dei
MlCROGRAPHIA.
ded inthofe bubbles, by the lofing of their agitation, by thedecreafe of the Heat,lofe alio moft part of their Spring and Expanfive power^it follows the withdrawing of the heat being very fudden) that the parts mutt be left in a very loofe Texture, and by reafon of the implication of the parts one about another,which from their iluggiftines and glutinoufnelslfuppofe to be much after the manner of the flicks in a Thorn-bufh,or a Lock of Wool^It will fol- low, I fay, that the parts will hold each other very ftrongly togethcr,and in- deavour to draw each other neerer together , and confequently their Tex- ture muft be very hard and ftirT^ but very much rarificd.
And this will make probable my next Pofition, That the parts of the Glafi are under a kind of tenjion or flexure3out of which they indeavour to extricate