•# DUKE UNIVERSITY I LIBRARY I treasure 'Room \ By the Council of the Royal Society of London for Improving of Natural Knowledge. Ordered, That the Book.^ritten hy Robert Hooke, M. A. Fellow of this Society ^Entitled^ Micrographia, or fome Phyfiological Defcriptions of Minute Bodies, made by Magnifying GlalTes, with Obfervations and Inquiries thereupon, Be Frintedby John Martyn ^and Janies Alleftry, Printers to the faid Society^ Novem, 23, 1664* Brolincker. P. R. S, MICROGRAPHIA e e O R S O M E Phyfiologkd Defcriptions MINUTE BODIES made by MAGNIFYING GLASSES WITH Observations and I n oja i r i e s thereupon* By R. HO 0 KEj Fellow of the R o y a l Society. lS!onpojJts ocnlo quantum contendere Linceus^ Non tamen idcirco contemn as Lippus inungi. Horat. Ep. Lib. i. LONDON^ Printed for James Allejiry^ Printer to the Royal Society, and are to be fold at his Shop, at the Rofe and Crown in Duck: Lane. M DG LX V 1 1, '1 a Di^rtifed by the Internet Archive in 2016 https://archive.org/details/micrographiaorso1670hook TO THE SIB, Do here moft: humbly lay this fmall Prefent at Tour Majejiies Royal feet. And though it comes accompa- -ny’d with two difadvantages, the meamefs of the Author, and of the Subjedi; yet in both I am incouraged by the greatnefs of your Mercy and your Knowledge. By the one\ am taught , that you can A forgive The Epistle forgive the prefumpnom Ofeniors: And by the other^ chat you will not e- jleem the leaftwork of Nature^ or Art-, unworthy yom Oh fervation.Psxm^{k. the many felicities that have accompani’d your Majejlies happy Reftauration and Government-, it is none of the leaft confi- derable, that Philofofhy and Experimental Learning have projpefd u nder your Royal Patronage. And as the calm profpericy of your Reign has given ms xhe kifure to follow thefe Studies of quiet rc' tirement-, fo it is juft, that the Fruits of them ihould , by way of acknowledge' ^ be ^'return’d to your Maj^y. There are, ""Sir, fevcral other of your Subjeds, of your Royal Sockty-,^:mm bufie about Nobler matters : The J«- 'provemenl of ManufaBwes and- Agficul- Pure-, Intreafe oi Commerce -, theTt/- ioMdge sA Navigation: In alb which they dfe afsiJledhY your Majejlies Incou' Lagphehi and Example, ” Amidft all thofe ■ greater Dedicatory. greater Defigns,! here prefume to bring in that which is more proportionable to the fmalnefs of my Abilities , and to offer fome of the leajl of all vifihk things^to that Mighty King^ that has efla- Uijhtan Empire over the heft of zlllnr vifihle things of this World, Minds of Men. Tour Majejlies mo fl humble ' -r-'- ' , and mojl obedient SubjeB andServant'i ^ T/- * -f.j \u OBERT ' H ooiCe. £tlj» 'V' *’5'* '^fo Oj*,> <{jK> TO THE ROYAL SOCIETY. ter my Addrejl to our Great Founder and ?a- tron^ I could not but think my felf oblig'd ^ in confideration of' thofe many Ingagements you have laid upon me , to offer thefe my poor Labours to this MOST 1 L L LI- STRIOIIS ASSEMBLY. YOU have been pleas’d formerly to accept of thefe rude Draughts, I have fince added to them fome Defcriptions-, and fome Conjebiures of' my own. And therefore, together with YOUR Acceptance^ I mu\\: alfo beg YOUR pardon.The Rules YOU haveprefcrib d YOUR felves in YOUR Philofophical Progrefs do feem the beft that have ever yet been praftis’d. And particularly that of avoiding Dogmatizing , and the efpoufal of any Hypothefis not fufhciently grounded and confirm’d by Experiments. This way feems the moft excellent , and may preferve both Philofophy and Natural Hiftory fromits former Corruptions In faying which, I may feem to condemn my own Courfe in this Treatife ; in which there may perhaps be fome Expreffions^ which may feem morepofitive then YOUR Preferiptions will permit: And though I defire to have them underftood only as CorijePiures and Quaeries (which YOUR Method does not altogether difallow)yet if even in thofe I have exceeded, ’fir. fit that I fbould declare, that it was not done by YOUR Direftions. For it is moft unreafonable, that YOU fbould nn&cvgo l\it imputation the faults of my Con^ jefiures^ feeing YOU can receive fo [mail advantage of reputa- tion by the fleight Ohfervations of TOVR moft humble and moft faithful Servant ROBERT HOOKE. 1 7* k the great prerogative of Mankind above other Creatures^ that we are not only able to behold the works of Nature^ or barely our lives by them^ but we havealfo thefower of Gonfidering^ _ comparing, altering, affifting, arid improving them to varioH6 ufes.And o5 this Is the peculiar priviledge of humane Nature in general^ fo Is it capable ofbeingfofdr advanced by the helps of Art^ and Experience, as to make fome Men excel others in their Obfervations, and I>eduhiions,almofl as much as they doBeafis. By the addition of fuch artificial I nftruments andmtt\\ods,there may be,in fome manner, a reparation made for the mifchiefs, and imperfeSiion, mankind has dr awn upon it felf by negligence,and intemperance, and a wilful and fuperjlitiotis deferting the P refer ipts and Rules of Nature, whereby every man,' both from a deriv'd corruption, innate and born with him, and from his breeding and converfe with men,is very fubjeH to flip into all forts of errors. The only way which now remains for us to recover fome degree of thofe former perfebf ions, feems to be,by reVtifying the operations of the ■ Scnik,the Memory, and Re?i{6n,fince upon the evidence,the Rrength, the integrity, and the right correfpondence 0/ all thefe,all the light, by which our aVuons are to be guided, is to be renewed, and all our com- mand over things is to be eftablijht. It is therefore moft worthy of our confideration, to recolleU their fe- fever al defeEis, that fo we may the better under fland how to fupply them, and by what affi fames we may inlarge their power, and fecure them in performing their particular duties. As for the afiions of .Senfes, we cannot but obferve them to be in a many The Preface. mart] particulars much outdone hy thofeof other Creatures^ and when at bejlpbe far Jhortof the perfection they feem capable of: And thefe infirmities of the Senfes arife from a double caufe^ either from theAxf- proporcion of the Objed to the Orgznyvhereby aninfinite 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 Uh 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 k either frivolous or falle ; and if good^ and fuhfiantial^ either in trad of time obliterated, or at befi fo overwhelmed and buried under more frothy notions^ that when there k need of them^ they are in vain fought for. The two main foundations being fo decehable^ it k no wonder^ that all the fucceedingworks which we build upon them^of arguing^ conclu- dingPefinirigfyudging^ and all the other degrees of Reafon^ are lyable to the fame imperfedion.) beings at befl^ either vain^ or uncertain : So that the errors of the underftanding are anfwerable to the two other ^ being defedive both in the quantity andgoodnefs of its kpowledge ; for the lU mits^ to which our tlmghts are confi ndr^ are fmall in refped of the vafi extent of Nature it felf ; fomepartsofit are too bicge to be comprehen- ded^ and fome too little to beperceived. And from thence it mufifoU lowy:hat not having a full fenfation of the Objed^ we mufl be very lame and imperfed in our conceptions about it , and in all thepropofitions which we build upon it ; hence, we often take the fhadow of things for the fubftance,y?w poffible., though that furlong jhould be ten times multiply d. And though fome famous Authors have affirm'd it impojfible to hear through the x\\m~ nell plate of Mulcovy-glafs ; yet Ikjiow a wayfby which tkeafie enough to hear one fpeak. through a wall a yard thick. It has not been yet thoroughly examindfiow far Otocoullicons may be improv'd.^ nor what other wayes then may be of quickning our hearing., or conveying found through ocher bodies then the A\r: for that that k not the only medium, I can affure the Reader .,that I havefiy the, help of a diftended mvcrpropa- The Preface. gated the found to a very confiderabte difiance in an inftant, or with as feeminglj quick, u motion as that of lights at kafi^ incomparably fwifter thenthat^ which at the fame time was propagated through the Air ; and this not only in a firaight line ^ or direbr^ hut in one bended in many angles. Nor are the other three foperfehl^ but that diligence, atcention, and many mechanical contrivances, may alfa highly improve them. For fince the fenfe of fmelling feems to be made by the fwife paflage of the Air ( impregnated with the fieams and effluvia of feveral odorous Bodies') through the grifiy mt^Lnders of the Nofe whofe furfaces are cover’d with a very fenfible nerve , and moiftned by a tranfuda- tion from the proceflus mamillares of the Brain , and fome ad- joyning glandules, and by the moifi fteam of the Lungs, with a Liquor convenient for the reception of thofe effluvia and by the adhefion and mixing (f thofe fieams with that liquor ^and thereby afebiing the nerve,, or perhaps by infmuating themfelves into the juices of the brain,, after the fame manner,, as I have in the following Obfervations intimated,, the parts of Salt topafi through the skins of Efs,, and Frogs, SincCi I fay,, fmelling feems to be made by fome fuch way,, 'tis not improbable,, but that fome con- trivance,, for making a great quantity of Airpafi quicKthroughthe Nofe, might O'i much promote the fenfe of fmelling,, as the any wayeshindringthat pajfage does dull and defiroyit. Several try ah I have made,, both cf hindring and promoting this fenfe^and have fucceeded in fome accordingto expebiation ; and indeed to me it feems capable of being improv'd,, for th6 judging cf the confiitutions of many Bodies, Perhaps we may thereby alfo ’-judge {as other Creatures feem to do) what is wholfomeyvhat poyfon ; and in a word, what are the ffecifick. properties cf Bodies, There may be alfo fome other mechanical wayes found out , of fenfibly perceiving the effluvia of Bodies ; feveral Infiances of which,, were it here proper, I could give of Mineral fieams and exhalations ; and it feems not impoffible, but that by fome fuch wayes improved, maybe difeovered, what Minerals lyeburied under the Earth, without the troubk 'to dig for them ; fome things to confirm this Conjebiure may be found in Agricola, and other Writers of Minerals, fteakjngcf the Vegetables that a re apt to thrive, or pine, in thofe fieams, f Whether . The P R E F A C E. Whether alfothofe fleams^ which feem ta ijfue out of the Earthy and mix with the Air ( and fo to precipitate fome aqueous Exhalations^where- with *tk impregnated ) may not be by fome way detebded before they produce the efe^^feems hard to determine ; yet fomething of thk kind I am able to difcoverdy an Injlrument I contriv'd to fbew all the minute variations in the pr e/fur e of the Air ; by which Iconfiantly find^that before , and during the time of rainy weather^ theprefure of the Air is lefi^ and in dry wea- ther , but efpecially when an Eaftern Wind ( which having pafl over vaft trails of Land k heavy with Earthy Particles ) blows^ it k much more^ though thefe changes are varied according to veiy odd Laws, The Infirument is this. I prepare a pretty capaceous Eolt-head A B, with a fmall ftcm about two foot and a half long D C 5 upon the end of this D I put on a Ifnall bended GlalsjOr brazen Syphon D E F ( open at D, E and F, but to be doled with cement at F and E, as occalion ferves) whole ftemF fhould be about fix or eight inches long, but the bore of it not above half an inch diameterjand 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 Board,or Frame, in fuch manner,that almoft half the head A B may lye buri- ed in a concave Hemifphere cut into the Board R S ^ then I place it lb on the Board RS, as is expreft in the firfi: Figure of thefirft 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 leaf!: fhake or ftir it ^ then drawing a line X Y on the Frame R T, fo that it may divide the ball into two equal parts, or that it may pafs, 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 5 then flopping the end F with loft Cement,orlbft Wax, I in- vert the Frame, placing the head downwards, and the Orifice E upwards ^ and by it, with a fmall Funnel, I fillthewholeGlalswith Qiiickfilver, then by flopping the fmall Orifice E with my finger, I oftentimes cred: 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,! fill it top full with clear and wellftraind 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 faff 5 and to fecure this Cement from flying out afterward,! bind over it a piece of Leather, that is Ipread over in the in- fide with Cement, and wound about it whilft: the Cement is hot : Having thus faftned it, 1 gently ereft again the Glals after this manner : ! 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 3 this ! do ,. that if there chance to be any Air hidden in the final! Pipe E, it may alcend into the Pipe F, and not into the Pipe D C : Having thus ereded 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 z{m2i\\Syfhen I draw out the Mercury fo longjtill I find the furfaee of it AB in the head to touch exactly the line X at which time I immedi- ateiy take away the Syphon , and if by chance it be run fomewhat below the line X Y, by pburing in gently a little Mercury at F, I raife it again to its defired height , by this contrivance I make all the fenlible rifing and fal- ling of the Mercury to be vifible in the furfaee of the Mercury in the Pipe and Icarceany in the head A B. But becaufe there really is feme (mall change of the upper forface allb, I find by fevei al Oblervationshow much it rifes in the Ball, and falls in the Pipe F, to make the dift ance between the awo lurfaces 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 jufined and divided it, I have a large Wheel M N O P, whole outmolHimb is divided into two hundred.equal parts , this by certain fmall Pillars is fixt on the Frame RT, in the manner exprell: 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 thole divilionsj which I find anfwertoan inch of alcent, or defeent, of Mercury : This Cylinder I, is movable on a very fmall Needle , 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 Imallfteel Bullets at each end of it G H^ one of thefe, which is fomev/hat the heavier, ought to be fo big, as freely to move to and fro in the Pipe F ^ by means of which contrivance , every the lead: 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 thk pihutone way of difeovering the effluvia of the ' Earth mixt with the Air ; there may be perhaps many othersyvitnejl the Hygrofeope^ an Inftrument whereby the watery fleams volatile in the Air are difeerned^ which the Nofe it felf vs not able to find, 7hvs I have deferib'd in the following Trahi in the Befeription of the Beard of a wild Oat. Others there are^ay be difeovered both by the Nofe , and by other wayes alfo. 7hu6 thefmo?k of burning Wood k fmelt, feen, and fuffickntly felt by the eyes: 7he fumes of burning Brimffone are fmelt and difeovered dfo by the deflroying the Colours of Bodies , as by the whitening of a red Rofe ; And who knows^ but that the Induflry of man^ following thk me- thodynay find out wayes of improving thk fenfe to as great a degree of per ^ fedfton as it k in any Animaf and perhaps yet higher. '7k not improbable alfofiut that our rafte may be very much improv'd., either by preparing our tafl for the Body., as., after eating bitter things., Wme.,or other Vinous liquors, are more fenfibly tafled ; or elfeby pre- paring The Preface, paring Bodies for our taft ; as the dijfolving of Metals with acid Liquors^ make them taftable^ which were bfore altogether infifid ; thu6 Lead be- comes fweetcr then Sugar ^ and'SWNtr more bitter then Gall^ Copper andiron ofmofl loathfome tofts. And indeed the buftneft of this fenfe being to difcover the prefence of diffolved Bodies in Liquors put on the Tongue^or in general to difcover that a fluid body has fome folid body diffolvd in iL and what they are ; whatever contrivance makes this difcovery improves this fenfe. In this kqnd the mixtures of Chymical Liquors af- ford many Inftances ; as the fweet Vinegar that is impregnated with Lead may be difcovered to he fo by the affufion of a little of an Alcalizate folution ; 7he bitter liquor 0 / Aqua fbrtis and Silver rnay be difcover d to be chargd with that Metals by laying in it fome plates of Copper : ^Tts not improbable alfoJ)ut there maybe multitudes of other wayes of difco- vering the parts diffolvd^ or difjoluble in liquors ; and what is this difco- very but a kind of lecundary tafting. ’7m not improbable alfof)ut that the fenfe of feeling may be highly im- provd^ for that being a fenfe that judges of the more grofs and robuft motions of the Particles of Bodies, feems capable of being improvd and ajfijied very many wayes. Thus for the diftinguifhing o/Heat and Cold^he Weather-glafs Thermometer, which Ihavedefcrib din this follow- ing Treatife., do exceedingly perfeSi it ; by each of which the leaft varia- tions of heat or cold., which the moft Acute fenfe is not able to diftinguifh.,are manifefted This is oftentimes further promoted alfo by the help of Burn- !ng-glaiIes,^J«J the lik^.,which colleH and unite the radiating heat. Thus the roughnefs and fmoothnefs of a Body Is made much more fenfible by the help of a Microfcope, thenby the moft tender and delicate Hand. Perhaps., a Phyfitian might., by fever al other tz.r\g\h\Q proprieties, difcover the conftitution of a Body as well as by the Pulfe. I do but inftancein thefey .0 fbew whatpojfibility there may be of many others., and what proba- bility and hopes there were of finding them^f this method were followed ; for the Offices of the five Senfes being to deteH either the fubtil and curi- ous Motionspropagated through all pellucid or perfectly homogeneous Bodies; Or the more grok vibrative Pulfe communicated through the Air and all other convenient mediums , fluid or folid : Or the effluvia The Preface. effluvia of Bodm diffblv’d in the Air ; Or the particles of ho£es diP folv’d or diflbluble in Liquors, or the more quick and violent king motion 0/ heat in all or cf ihefe: whatfoever does ar^mjesfro^ mote artj of tbefe kinds of criteria, does afford a of improving fomi onefenfe. And what a multitude cf thefe would a diligent Man meet within his inquiries ? Andthk for the helping and promoting the fenii* tive faculty on^» Next^as for the Memory, or retentive faculty, we maybe fufficienty' inflrubied from the written Hiffories of civil adHons, what great afft-^ fiance may be afforded the Memory^ in the committing to writing things ob- fervable in natural operations. If a Fhyfitian be therefore accounted the more able in his Faculty^ becaufe he has had long experience and praHice, the remembrance of which^ though perhaps very imperfeU^ does regulate alt his after aHions : What ought to be thought of that man^ that has not only a perfect regifter of his own experience j)ut is grown old with the experience cf many hundreds of years^ and many thoufands of meri. And though of late , men^ beginning to be fenfible of this convetitence^ haue here and there reglfired and printed fome few Centuries, yet for the mofipart they are fet down very lamely and imperfebUy^ and^ I fear ^ many times not fo truly ^ they feeming^ fever al of them^ to be defigridmore for Oftentation publique ufe .* Forgiot toinfiancepthat they do for the mofipartpornitthofe Experiences they have made ^ wherein their Patients have mifearriedft is very eafie to beperceiv d^hat they do all along hyper- bolically ektol their own Preferiptions^ and vilifie thofe of others. Not- withfianding all which ^ thefe kinds of Hifiortes are generally efieem'd ufe- ful^ even to the ablefi Fhyfitian, What may not be expelled from the rational or dedudf i\^c Faculty that is furnfht with fuchM^tetidls^ and thofe fo readily ndzpted^ and rangd for ufepthat in a moment^ ^ ^twere^ thoufands of Jnfiances^ ferving for the illufrration,determination, or invention, of almofi any inquiry^ reprefented even to the fight ? Howneer the nature of Axioms mufi all thofe Propoff cions which are examindb fore fo many nefles ? And how difficult will it be for any^ though never fo fiubtil an er- ror in Philofophy^ to feape from being difeovefd^ after it has indufdthe touchy and fo many other d - What The Preface. What kind of mechanic alwaj^ andphjfical invention alfo m there re- quird^that might not thi^ way be found out ? The Invention of a way to find the Longitude of places k eafily perform'd^ and that to 06 great per- fection 06 16 defifd^ or to 06 great an acciiratenefs 06 the Latitude cf places can be found at Sea ; and perhaps yet alfo to a greater certainty then that has been hitherto founds as I flj all very Jfeedily freely manifefi to the world. The way 0/ dying in the Air feems principally unprabUcable^ by reafon of the want of ftrength in humane mufcles ; if therefore that could be fuppli dfit werej think.-) eafie to make twenty contrivancesto perform the office of 'N mgs : What Attempts alfo I have made for the [applying that Defeoi^ and my fucceffes therein^ which^ Ithink.^ are wholly new ^and not inconfiderable^ I Jh all in another place relate. ^Ti 6 not unlikely alfo., but that Chymifts, iffthey followed thus method., might find out their fo much fought for Alkaheft. What an univerfal • Menftruum , which diffolves all forts of Sulphureous Bodies, lhave difcover'd ( which has not been before taken notice of as juch ) lhave Jhewn in the ftxteenth Obfervation. What a prodigiou 6 variety of Inventions in Anatomy has this latter Age afforded., even in our own Bodies fn the very Heart, by which we live, andtheBvdmyvhich is the feat of our knowledge of other things ? witnejl allthe excellent Works of Pecquet, Bartholinus, Billius, and many others ; and at home,ofDobiorU 2 irvy,Do 5 ior Rnt,Dobfor Wi\l\s,DoSior Gliflbn. //^Celeftial Obfervations we have far exceeded all the An- tients,even the Chaldeans and Egyptians thernfelves, whofe vail: Plains, high Towers,^^W clear Air, did not give them fo great advantages over us, as we have over them by our Glades. By the help of which, they have been very much outdone by the famous Galileo, Hevelius, Zulichem ; and our own Countrymen, Mr. Rook, Boldor Wren, and the great Orna- ment of our Church and Naticn,the Lord Eilhop of Exeter. And to fay no more in Aerial Difeoveries, there has been a wonderful progref made by the Noble Engine of the moft Illuftrious Mr. Boy\t,whom it becomes me to mention with all honour:^ not only as my particular Fatron,but as the Patron of Philofophy it felf ; which he every day increafes by his La- bours, and adorns by his Example. The The P P. E F A C E. The good fuecejl of all thefe great Men^and many others^ and thi feemingly great obvioufneis of mofi of their and divert other Inventions^ which from the beginning of the world have been^ as \were^ trodon^ and yet not minded till thefe lafi mquifidve Ages ( an Argument that there may be yet'behind multitudes of the like ') puts me in mind to recommend fuch Studies^and the profecution of them by fuch methods^ to the Gentlemen of our Nationyrhofe \d\{\xrc makes them fit to undertake, and the plenty of their fortunes to accomplilh, extraordinary things in this way. And I do not onlypropofe this kind of Experimental Philofophy as a matter of high rapture and delight of the mind^ but even as a material and fenfi- ble Pleafure. So vaji is the variety of Objefls which will come under their InfpeViions., fo many different wayes there are of kindling them., fo great is the fatisfaflion-o/ finding out new things, that I dare compare the contentment which they will injoy.,notonlytothatcf contemplation, but even to that which mofi men prefer of the very Senfes themfelves. And if they will pleafe to tak^ any incoUragement from fo mean and fo imperfect endeavours as mine., upon my own experience., I can afure 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 ( wPich I may on fome other opportunity explain ) I have been able prefently to examine the poffibility of it ; and if fo, as eafily to ex- cogitate divers wayes of performing it : And indeed it ispoffible to do as much by this method in Mechanicks, as by Algebra can be perform'd in Geometry. Nor can I at all doubt, but that the fame method is as ap- plicable to Phyfical Enquiries , and as likely to find and reap thence as plentiful a crop of Inventions ; and indeed there feems to be no fubjeH fo barrenfiut may with this good husbandry be highly improvd. Toward the profecution of this method Phyfical Inquiries, / have here and there gleaned up an handful cf Obfervations, in the colleHion of mofi of which I made ufe o/Microfcopes, and fome other Glades 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 uncol- ldied,obvious enough without the helps of Art , hut only to promote the ufe of Mechanical helps for the Senfes, bath in the furveying the already vifible World, The P E F A C E. Worlds and forthedifcoveryofman^ others hitherto unknown^ and to mak^ usyvith the great Conqueror yto be afehtedthat we have notyet overcome one World when there are fo many others to be difcovend^ every confiderable improvement Gf'Xc\cico'^c?> or Microfcopes producing new Worlds and Tcrra-Incognitasto our view. The Glaffes lufed were cf our Engllfh mahejjut though very good of the kjnd^ yet far Jhort of what might be expe^ed^ could we once find a way of mahqng Glaffes Elliptical., or of fome more true fib ape ; for though both Microfcopes, and T elcfcopcs, as they now are., will magnifie an Objed about a thoufand thoufand times bigger then it appears to the naked eye ; yet the Apertures of the Objebii-glalfes are fo very final f that very few Rays are admitted, and even of thofe few there are fo manyfalfe, that the ObjeU appears dark ^;z^indiftind : And indeed thefe inconveniences are fuch,06 feern infeparable from Spherical Glaffes, even when mofi exaSily madefiut thtway we have hitherto made ufe of for thatpurpofe k fo imperfehl,that?^there may be perhaps ten wrought before one be made tolerably good, and mofi of thofe ten perhaps every one differing in goodnefi one from another, which k an Argument,thatthe way hitherto ufed k,at leafi,very uncertain. So that thefe Glaffes have a double dfeRi'ghe one,that very few of them are exactly true wrought ; the other, that even cf thofe that are befi among them, none will admit a fufficient number of Rayes to magnifie the Objehi beyond a determinate bignefi. Againfi which Inconveniences the only Remedies I have hitherto met with are thefe. Firft, for Mkroficpes ( where the Objcdt we view is near and within our power)the bell: way of making it appear bright in the Glalsjis to call: a great quantity of light on it by means convex gUfies.gox therebyjthough the aper- ture be very fmalkyet there will throng in through it luch multitudesjthat an Objedc 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 Ibme Room that has only one window open to the South , and at about three or four foot diftance from this Window jOn a Table, I place my Microfcope, 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 colleded and thrown upon the Objedt ; Or if the Sun fhine, I place a (mail piece of oyly Paper very near the Object, be- tween that and the light , 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 Objed 5 yet I lb proportion that light, that it ’ may The Preface. may not fingc or burn the Paper. Inftead of wbieh Paper there may be made ufe of a fraall piece of Looking-glafs plate , one of whole fides is made rough by being rubb’don aflat Tool with very fine land, this will, if the heat be leifurely call: 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 Objeft, 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 Objeds, for by this means the light isfo equally diffuled, that all parts are alike inlightned 5 but when the immediate Tight 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 themfelves alfo, by reafon of the in- equality of light, indiftind, and appear only radiant Ipots. But becaule the light of the Sun, and alfo that of a Window, is in a conti- ’ nual variation, and fo many Objeds cannot be view’d long enough by them to be throughly examin’d 3 befides that , oftentimes the Weather is io dark and cloudy, that for many dayes together nothing can be view’d : And be- caufe alfo there are many Objeds to be met with in the night, which cannot (b conveniently be kept perhaps till the day, therefore to procure and caft a fufficient quantity of light on an Objed in the night, I thought of, and often ufed this. Expedient. I procur’d me a fmall Pedeftal , foch as is deforib’d in the fifth Figure of the Scheme on the {mall Pillar A B, of which were two . movable Armes CD, which by means of the Screws EF, I could fix in any part of the Pillar 3 on the undermoft of thde I plac’d a pretty large Globe of Glais G, fill’d with exceeding clear Brine, ftopt, inverted, and fixi in the m^mner vifible in the Figure 3 out of the fide of which Arm proceeded another • Arm H, with many joynts 3 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 fo 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 exprefi: in the Figure, with the (mall flame of a Lamp may be caft as great and convenient a light on the Object as it will well indure5and being always conftant, and to be had at any time, I found moft proper for drawing the reprelentations of thofe fmall Objects I had occafion to obierve. 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 Objed-glaft of fuch a Figure as would conveniently bear a large Aperture, As for Telefcopes, the only improvement they feem capable of is the increafmg of their length ; for the Objebi being remote^ there U no thought of giving it a greater light thin it has ; and therefore to augment the Aperture^ the Glajl mujl be ground of a very large ^here ; for ^by that . e meanSy The P R E F A C E. means^the longer ihe Gkjl be^ the bigger aperture mil it bear^if the Glafes be of an equal goodnefi in their kind, .Ther^ore a fix will indure a much larger Aperture then a three foot Glafi ; and a fiyty foot Glafl will proportionably bear a greater Aperture then a thirty ^and will as much ex- cel it alfo 06 a fix foot does a three foot,, as I 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 mak^ the Objehi proportionably big and difinhi ; whereas there are very few thirty foot Glajfesthat will indure an Aperture of more then two in- ches over. So that for Telcfcopcs , fuppofing we had a very ready way of making, their Objehi Glafes of exahily ffherical Surfaces^ we might,, by increafwg the length of the Glafi,, magnifie the Objehi to any afignable big- nefl. And for performing both thefe,, I cannot imagine any way more ea^ fie,,and more exaht,, then by thus following Engine fy means of which,, any Glafes,,of what length foever^may be fpeedily made, It feems the moji eafie,, hecaufe with one and the fame Tool may be with care ground an Objeli Glajl,, of any length or breadth requifite , 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 exalt , for to the very loft firofie the Glafi does regulate and reHifie the Tool toitsexaH Figure ; and the longer or more ' the Tool and Glajl are wrought together,, the more exaH will both of them be of the defird Figure, Further,, the motions of the Glafi and Tool do fo crofi each other , that there is not one point of either s Surface fiut has thoufands of crofi motions thwarting it ,, fo that there can be no kind of Kings or Gutters made either in the Tool or Glafi, The contrivance of the Engine is, only to make the ends of two large Mandrils fb 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 produc’d, may meet each other in any aflignable Angle 5 both which reqiiifites may be very well perform’d by the Engine deferib’d in the third Figure of the Scheme : where A B fignifies the Beam 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^whoik tapering neck F runs in an adapt- ed tapering brafs Collar 5 the other end E runs on the point of a Screw G ^ in a convenient place of this is faftned H a pully Wheel, and into the end of itjthat comes through the Poppet head C, is ferewed a Ring of a hollow Cj/linderK, or fome other conveniently fliap’d Tool, of what wideneis fliall be The Preface. be thought moft proper for the cize of Glafles , about which it is to be ini° ploy’d: As, for Objeft glaffes, between twelve foot and an hundred foot long 3 the Ring may be about fix inches over , or indeed fomewhat more for thofe longer Glaifes. It would be convenient alfo, and not very chargeable 3 to have four or five feveral Tools, as one for all Glafles between an inch and a foot , one for all Glafles between a foot and ten foot long, another for all between ten and an hundrcdja fourth for all between a; hundred and a thoufand foot long; and if Curiofity lhall ever proceed fo far, one for all lengths between a thoufand and ten thouland foot long for indeed the principle is fuch,that fuppofing the. well madCjandof a good length, and fuppofing great care be uled in working and polifliing them,I fee no reafon,but that a Glals of a thoufand,nay of ten thoufand foot long, may be as well made as one of ten ; for the reafon is the lame,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 gi=eat a regularity in its parts as to reffadion ; 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 the Glafs : The other Mandril is fhap’d like this, but it has an even neck in- flead 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 ftill adjuftned to the wearing or wafting neck : into the end of this Mandril is ferewed a Chock N, on which, with Cement or Glew is faftned the piece of Glafs Q_ that is to be form’d ; 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 ferews, the manner whereof will be fufficiently evidenc’d by the Figure) in fuch an Angle as is requifite to the forming of flich a Sphere as the Glals is dc- fign’d to be of ; the geometrical ground of which being fufficiently plain, though not heeded before, I fhall,. for brevities fake, pals over. Thislaft Mandrills to be made ( by means of the former, or Ibme other Wheel ) to run round very fwift alfo , by which two crols motions the Glals cannot chufe ( if care be us’d ) but be wrought into a moft exadly fpherical Surface. But becaufe we are certain^ from the Laws of refraction ( which 1 I havee^erimentally founJtobe fofy an Infirument I p.mll prefently de^ feribe ) that the lines of the angles- of Incidence are proportio- nate to the lines of the angles of RefraClion, thereforeif Glapes could he made of thofe kind of Figures^ or fome other ^ fuch the moft incompa- rable Les Cartes het^ invented^ and demonftrated in hks Philofophicaland Mathematical U^orks-tWe might hope for a much greater perfehiion of Optick^ then can be rationally expelled from fpherical ones\ for thoughyzxtcns^z- ribus, wefind^ that the larger the Telefcope OhjePi Glajfes are^ and the Jhorter thofe of the Microfco^e^ the better they magnifies yet both of thew.^ The Preface. befiJi fuch determinate Jimenfions , are by certain inconveniences rendred unufeful; for it willhe exceeding difficult to make and manage aTube above an hundred foot long, and it will be as difficult to inlightcn an Objebi lejl then an hundted part of an inch dijlant from the Obje^i GlaJ^, I have not as yet made any attempts of that kind^ though I know two. or three w^es^ whicb^ as far asl have yet confidered^ feem very prohable^and may invite me to mak§ a try at as foon as I have an opportunity^ of which I may hereafter perhaps acquaint the world. In the Interim ^ I pjalldefcribe the Inftrument I even now mention'd^ by which the refrz^’ion of all kinds of Liquors may be mofl exaHly meafurd^ thereby to give the curious an opportunity cf making what further try ah (f that kind they ffall think requifite to any of their intended try ah ; and to let them fee that the laws of RefraHion are not only notional. The Infti'umcnt confifted of five Rulers , or long pieces placed together, after the manner cxpreft in the fecond Figure of the firft Scheme y 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 , on the back fide of which was hung afmall plummet by a line ftrctcht from top to bottom, by which this piece was fet exactly upright,and fo very firmly fixt 5 in the mid- die of this was made a hole or center, into which one end of a hollow cy- lindrical brafsBox CC, fafhion'd asifihallby and by defaibe, v/as plac’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 afmall arm DDi 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 crols’d with two fmall threads, and at the end of it was fixt a Imall 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 Ibme fixty degrees,and each degree was fub- divided into minutes , fo that putting the crofs of the threads in E upon any part of this divided line , I prelently 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 anypofition. The other Ruler allb RS was made- much aftet; the lame manner, only it was not fixt to the hollow cy lindrical Box, but,by means of two fmall brais Armes or Ears, it mov’d on the Centers of it 5 thisalfo, by means of the crofs threads in the hole S, and by a Screw in K, could be faftned on any divifion of another line of cords of the fame radius drawn on N O. And fo by that means, the Angle made by the two Rulers, A B and R S, was allb known. The Brafs box CC in the middle was lhap’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 thefides and bottomeswascutout, lb that The Preface. that the Box, \^hen the Pipe and that was joyne d to it;, would contain the Water when fill’d half full, and would likewife, without running over^ in- dure to be inclin’d to an Angle j equal to that of the gteatefi: refraiSion of Watetj and no morejWithout running over. The Ruler E F wasfixt very fall to the Pipe Vj fo that the Pipe V dirededthe length of the RulerE Fjand the Box and Ruler were mov’d on the Pin TT, (b astomakeahydefi- rable Angle with the Ruler AB. The bottom of this PipeV wasftop’d with a fmall piece of exactly plain Glafs j which was plac’d exaftly per- pendicular to the Line of diredtion^ or of the Ruler E F. The Pins alfo T T were drilfd with fmall holes through the Axis^^nd through thofe holes was firetcht and faftned a fmall Wire. There was likewife a fmall Pipe of Tin loofiy put on upon the end of V, and reaching down to the fight G 5 the ufeof which was only to keep any falle Raves of light from palling through the bottom of V;) and only admitting llich to pals as pier- ced through the fight G; All things being placed together in the manner deferib’d in the Figure 5 that is, the Ruler A B being fixt perpendicular, I fill’d the Box C C with Water, or any other Liquor, whofe refradlion I in- tended to try 3 till the Wire pafling through the middle of it v/ere 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 x and looking through the fight I, I moved the Ruler R S to and fro, till I perceived the light paF 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, lobferved what degree and part of it was cut by the crofs threads in S. And this gave -me the Angle of Inclination, APS anftveringto the Angle of Refraftion BPE : for the furfaceof 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 mcafure, or be the Angle of Inclination in the Liquor 5 next EPB muftbe the Angle of Re- fradion,for the Ray that paftes through the fight G, paftes alfo perpendicu- larly through the Glafs Diaflragme at F, and confequently alfo perpendi- cularly through the louder furface of the Liquor contiguous to the Glafs, and therefore fuffers no refraaion till it meet with the horizontal furfaceof the Liquor in C C, which is determined by the two Angles. By means of this Injlrument lean with\\xx\.t trouble, and a very fmall quantity of any Liquor, examine^ rnoft accurately^ the refradion 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 Oylof Turpentine has a much greater RefraHion then Spirit of Wine , though it be lighter ; and that Spirit of Wine has a greater BefralHon then Water, though it be lighter alfo ; hut that lalt Water alfo has a greater RefraHion then frefh, though it be heavier : but Allum water has a lef tefraHlon then common Water, though hea-^ vier alfo. So that it feems^as to the refradion made in a Liquor f he ipeci- The Preface. fick gravity li of no efficacy, By thhihave alfofound4hatlook.what^vo^ portion the Sine of the Angle of Inclination ho6to the Sineo^' Angle of Refradion, correffondent toit^ the fame proportion have all the Sines (f other Inclinations to the Sines of their appropriate Refr anions, My way for meafuring how much a Glafs magnifies an Objefl:, plac’d at a convenient diftance from my eye^is this. Having reftifi’d the Microfiope^ to fee the defir’d Objeft through it very diftinftly, at the fame time that I look upon the Objeft through the Glafs with one eye, I look upon other Objeds at the fame diftance with my other bare eye 3 by which means I am able, by the help of a divided into inches and fmall parts, and laid on the Pedefial of the Mkrofcope^to caftjas it were, the magnifi’d appearance of the Objed upon the Ruler, and thereby exadly 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 fixth Figure of the firft Scheme^ the Tube being for the mofi: part not above fix or feven inches long, though, byreafon it had four Draw- ers, it could very much be lengthened, as occafion required 5 this was con- triv’d with three Glafles^a fmall Objed 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 Objed 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 Objed Glafs, for always the fewer the Refradions are, the more bright and clear the Objed appears. And therefore ’tis not to be doubted , but could we make a Microfeope to have one only refradion, it would, ceteris paribus^ far excel any other that had a greater number. And hence it is, that if you rake a very clear piece of a broken Few/Ve 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 Globul, or drop, which will hang at the end of the thread ^ and if further you flick feveral of thefe upon the end of a flick with a little fealingWax,fo as that the threads frand upwards, and then on aWhetflonefirflgrind 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 fmocth, if one of thefe befixt with a little foft Wax againfl a fmall needle hole,prick’d through a thin Plate of Brafs, Lead, Pewter, or any other Me- tal, and an Objed, plac’d very near, be look’d at through it, it will both magnifie and make feme Objefts more diflind then any of the great fcopes. But becaufe thefe, though exceeding eafily made, are yet very trou- blefometo be us’d,becaufe of their fmalnefs,and the nearnefsof the Objed 3 therefore to prevent both thefe, and yet ha ve only two Refradions, I pro- vided me a Tube of Brafs, fhap’d much like that in the fourth Figure of the firfl Scheme 5 into the fmaller end of this I fixt with Wax a good piano con- vex The Preface. Objed GlafsjWith the convex fide towards the Objed'j and into the bigger end I fixt alfo with wax a pretty large piano Convex Glafs, with the convex - fide towards my eye , then by means of the fmall hole by the fide , I fill’d the intermediate fpace between thefe two Glaflfes with very clear Water, and with a Screw flopp’d if in 5 then putti&g on a Cell for the Eye, I could perceive an Ob jed more bright then I could when the intermediate fpace was only. fiird with Air_,but this, for other in- conveniences, I made but little ufe of. ' My way for fixing both the Glafs and Objefb to the Pcdeftal moft conve- niently was thus : Upon one fide of a round Pcdeftal A B, in the fixth Fi- gure of the firft Scheme fixt a Imall Pillar C C, on this was fitted a Imall Iron Arm D, which could be mov’d up and down, and fixt in any part of the PiUarjby means of a fmall Screw E 5 on the end of this Arm was a fmall Ball fitted into a kind of focket F,made in the fide of the Brals Ring G, throng ' which the fmall end of the Tube wasfcrew’d^ by means of which contri- vance I could place and fix the Tube in what pofture I defir’d ( which for many Obfervations was exceeding neceflary ) and ad juften it moft exactly toanyObjeft. For placing the Objed,! made this contrivance 5 upon the end of a fmall brals Link or Staple H H, I fb faftned a round Plate 1 1 , that it might be turn’d round upon its Center K , and going pretty ftiff , would ftand fixt in any pofture it was fet 5 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, whofe top juft flood over the Center of the Plate 5 on this top I fixt a fmall Gbjed, and by means oi thefc contrivances I was able to turn it into all kind of pofitions, both to my Eye and the Light 5 for by moving round the fmall Plate on its center, I could move it one way, and by turning the Pin M, I could move it another way , and this without ftirring the Glafs 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 it alfo in any Pofition, by means of a Nut N, which was ferew’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 no defeription Now though thk vpcre the Inftrument I made moft ufe oft yet I have made fever al other Try ah with other kinds of which both for and forvciwere very dijferent from common ft^herical Glaffes, lhave made a Microfeope with one piece of Glaft^ both whofe furfac-es were plains. I have made another only with a piano concave, without any kind of reflebiion^ divers alfo by means of refledion. I have made ethers Waters, Gums, Refins, Salts, AiTenick, Oyls, and with divers other mixtures 0 / watery and oy\y Liquors. Andindeedthe fubje5i PS capable of a great variety ; but I find generally none more ufe^ fulthenthat which ia made with two fitch asl have already de^- What The Preface. What the things are I obfervd^ the following defcriptions will manifefi ; 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 I prefmnCy ( maj^ of them, atkafl')willbe new, and perhaps not lefi ftrange; Some fpecimeri of each of which Heads the Reader will find in the fubfequent delineations^ and indeed of fome more then I was willing there fljould be-,, which Was occafioned by my firfl Intentions to print a much greater number then I have fence found time to compleat. Of feuch therefore as lhad^l fdefi- edonly fome few of every Head^ which for fome particulars feerndmoflob- fervable^ rejeHing thcrefe as feuperfluous to the prefent Defegn. What each of the delineated Subjects areqthe following defcriptions an^ next to each will inform^of which I fejallhere^ only once for alf add^ That in divers cf them the Gravers have pretty well follow d my direHions and draughts ; and that in making of them^ I indeavouted Q as far as Iwas able ) firfl to difeover the true appearance , and next to mak^ a plain re- prefentation of it. This I mention the rather , becaufe of thefe kind of ObjeHs there is much more difficulty to difeover the true floape , then cf thofe vifeble to the naked eye^ the fame ObjeM feeming quite differing^ in one pofition to the Light,, from what it really is,, and may he difeover d in another. And therefore I never began to make ary draught before by many examinations in feveral lights^ and in fever al pofitions to thofe lights,, I had difeover' d the true form. For it is exceeding difficult in fome Objebis , to difeinguifh between a prominency and a depreffion^ between a (hadow black ftain, ora reflexion ^;?^^whitenefs in the colour. Befides,, the tranffarency of mofe ObjeHs renders them yet much more difficult then if they were opacous. Tl)e Eyes of a Fly in one kind of light appear almofi like a Lattice,, drill'd through with abun- dance of fmall holes ; which probably may be the Reafon, why the Ingeni- ous Dr. Power feems to fuppofe them feuch. In the Sunfhine they look, like a Surface cover'd with golden Nails ; in another pofeurejikc a Sur- face cover'd with Pyramids ; in another with Cones ; and in other po- fiuresof quite other flj apes \ but that which exhibits the beft,, is the Light collePled on the Objelt,, by thofe means 1 have already deferib'd, , / The Preface. And th'ps undertaken in profecution of the ^efign which the ROY- AL SOCIETY ho6 propos'd to it felf For the Members of th'e Affemhly ha- ving before their eys fomany fatal Infiances of the errors and faljhoodsfn which the greatefipart of mankind has fo long wandred^ becaufe they rely d upon the firength oj humane Eeafon alone ^ have begun anew to correH all Hy- porhefes by fenfe^ cus Seamen do their dead Reckonings by Coeleftial Obfervations;^;?^ to thispurpofe it has been their principal indeavour to en- large isf ftrengthen the Senfes by Mcdicine^and by fuch outward Inftru- ments as are proper for their particular works.. By this means they find form reafon to fufiehi^hat thofe efehts ofBodiesyvhich have been commonly attri- buted to Qualities, and thofe confejl’d to be occult, are perform' dby the Machines of Nature.^ which are not to be difeernd without thefe helps^ feeming themeerproduHs ofMotion^Figurc^and Magnitude; and that the Natural Textures, which forne call the Plaftick faculty, may be made in l.oomsyvhich a greater perfehrion of Opticks may make difcernable by thefe Glaffesfo as now they are no more puzgled about themyhen the vulgar are to conceive fiowT 2 c^t.?iry or fiowred Stuffs are woven. And the ends of all thefe Inquiries they intend to be the Pleafurc of Contemplative minds^ but above all^he eafe and difpatch cf the labours of mens hands. They do indeed neg- leH no opportunity to bring all the rare things of Remote Countries within the compafi of their knowledge and pr alike. But they fiill acknowledg their moft ufeful Informations to arifefrom common things., and from diverfifying thexr mofi ordinary operations upon them. They do not wholly rejeH Experi- ments cf meer light and theory ; but they principally aim at fuch., whofi Applications will improwe. Tend facilitate the prefentway ^Manual Arts. And though fomemen., who are perhaps taken up about lefi honourable Em~ ployments., are pleas'd to cenfure their proceedings., yet they can fhewmore fruits cf their firfi three years., wherein they have, off embled., then ary other Society in Europe can for a much larger /pace cf time.'Tis true., fuch un- dertakings m theirs do commonly meet with fmallincouragement ., becaufe men are generally rather taken with the plaufible and difcurfive, then the real and the folid part of Philofophy ; yet by the good fortune of their inflitu- tionfn an Age of all others the mofi\n(o^\i\I\mc^chey have been afflfied by the contribution and prefence ^ very many of the chiefFloMihcy and Gentry, g and The Preface. and other s^vfho are fome of the moft confiderable in their fever al Profefions. But that that yet farther convinces me cf the Real efteem that the more fe- rious part of men haveof thhSocicty^k^that fever al Merchants, aPx in earneft(whofe Objeld h meum isn\mrc\^that great Rudder (f humane affairs')have adventur'dconfiderahle fums of Money 40 put in prabUcewhat fome of our Members have contrived^ and have continued ftedfaft in their good opinions of fuch Indeavours^ when not one of a hundred of the vulgar have believed their undertakings feafable. And it is alfofit to be addedyhat they have one advantage peculiar to themfelves^hat very many of their num- ber are men of Converfe and Traffick ; which is a good Omen^ that their attempts will bring Philofophy from words to 2.d.\on feeing the men ofBufi- nefi ha ve had fo great a ffaare in their fir ji foundation. And of this kind I ought not to conceal one particularGeneroitty^which more nearly concerns my felfit is the munificence of Sir JohnCutler,?;2 endowing a Lehiurefor the promotion o/Mechanick Arts, to be governed and directed byJhisSociQty . 7 bis^ounty I mention for the Honourablenefs of the thing it felfandfor the expehiation which I have of the efficacy of the Example for it cannot now be objected to themy^hat their Defigns will be efieerned frivolous andwTiin.^ when they have fuch a real Teftimonyo/ the Approbation of a Man that is fuch an eminent Ornament (f this renowned City., and one., whofy Variety, and happy Succefs, (f his negotiations.^ has given evident proofs., that he is not eafie to be deceiv'd. This Gentleman has well obfervd., that the Arts of life have been too long imprifon’d in the dark, fibops of Mechanicks themfelvesds there hindred from growth, by ig- noranceyor felfinterefi:and he has bravely freed them from thefe inconveni- cnccsiHehath not only obliged 'Vr2.dt{vc\(st\fiut Tradeit felfiHe has done a work that is worthy of London, and has taught the chief City of Commerce in the world the right way how Commerce istobeimprov d. We have already feen many other great figns of Liberality and a large mind., from the fame hand:For by his diligence about t^eCorporation for the Poor ;^ji his hono- rable Subferiptions/or the rebuilding of St.PzuYsfiy hkchearful Disburf- ment for the replanting o/Ireland,(Z«^/ by many other fuch publick works, he has fhewn by what means he indeavours to eftablifh Afr/Tzo/y ; und now by this laftgift he has done thafgwhkh became one of the wifeft Citizens of The Preface. (four Nation to accomplijh^ feeing one of the wifeft of our Sratefmen,the Lord Verulam, propounded it. But to return to my Subje^^from a digrejfwn^ which^ Ihope^my Reader mil pardon me^ feeing the Example k fo rare that lean mak^no more fuch digreffions. Ifthefe my firfi Labours fljallbe any wayes ufefulto inquU ring men^ I muft attribute- the ineouragement andpromotion of them to a ve- ry Reverend W Learned vphom thk ought in juf ice to be faid^ That there is fcarce any one Invention, which this Nation has pro- duc’d in our Age, but it has force way or aher been fet forward by his affiftance. My Reader fbelieveyrill quickly ghejl^that it k Dr. Wil- kins that I mean. He k indeed a man horn for the good of rmnVm&.^and for honour of Country. In the {weetne(s<3/ whofebd-mioweynthe calmnefs -o / hk mind, in the unbounded goodnefs oj hk heart, we have an evident Inftance., what the true and the primitive unpafoonate Religi- on bfore it was fowred by particular FaSions. h a word.^ hk Zeal has been fi conftant and ededuaJ in advancing all good and profitable Aris^hat as one (f the Antient Romans faid <^Scipio, That he thanked God that he was a Roman ; becaufo whereever Scipio had been l>orn, diere had been the foat of the Empire of the world : So may I than! God.^ that Dr. Wilkins Englifhman, jor whereever he had lived., there hadbeen the chief Seat of generous Knowledge and true Phiioib- phy . To the truth of thkyhire are fs many worthy men living that will fuh- feribe., that I am confident., what 1 have here fauf will not be Ipokid upon., by aipj ingerimtus Reader ^ Panegyrick, but only 06 ^ real tefli- mony, .c By the Advice (f thk Escelient man I firji fa upoa thk Enterprife^ya fiill came to it with much Btlv^^ncy fiecaufe I was to follow the footflepsof fo eminertta Perfon as Dr. Wren , who was the firfi that attempted any thing cf thk nature ; whofe original draughts do now mah^ one of the Orna- ments of that great Collection cf Rarities in the Kings Clofct. Thk Ho- nor, which hk firfi beginnings of thk kind have receiv'd., to be admitted in- to the mofi famous place of the world filid not fo much incourage, as the ha- zard of coming after Dr. Wren di// affright me ; for of him Imufi affirm., ^thatffince the time Archimedes, there fcarce ever met in one man., in fo great The Preface. great a, perfeciion^ fuch a Mechanical Hand, anJ fo Philofophical Mind. But at lajlj)dng affuredboth by Dr. Wilkins, Dr. Wren himfelf\ that he had given over hi^ intentions of profecuting it^ and not finding that there veas any elfe defignd the purfuing of itjfet upon thk undertakings and W06 not a little incouragd to proceed in itsbythe Honour theRoysl Society W06 pleas'd to favour me withsin approving of thofe draughts (which from time to time as I had an opportunity of defcribingf I prefented to them. And particularly by the Incitements of divers of thofe Noble and excellent Per^ fons of its ^ore efpecial Friends^who were not lefi urgent with me for thepublijfnngs then for the profecution of them. After I had almofi compleated thefe Piltures and Obfervations ( ha~ ving had divers of them ingraven , and was ready to fend them to the Prefix I was inform'd s that the Ingenious Phyfitian F)r, Henry Povfer had made Microfcopical ObfervationSswhich had I not afterwar ds^ upon our interchangably viewing each others Papers^ found that they were for the moftpart difering from mines either in theSubjeH it felfs or in the particulars tak^n notice of ; and that his defign was only to print Obfer- vations without PiUureSsI had even then fuppreflcd what Ihad fo farpro-^ ceeded in. But being further excited by fever al of my Friendss in compty- ance with their opinionss that it would not be unacceptable to fever al inqui- fitive Mens (tnd hoping alfo , that I Jhould thereby difcover fomething New to the Worlds I have at length cafl in my Mitel into the vaft Treafu- rycf A Philofophical Hiftory. And it k my hope, as well as belief^ thsrt thefe my Labours will be no more comparable to the Produftions of many other Natural Philofophers, who are now every where bufie about greater things ; then my little Obje&s are to be compar'd to the greater and more beautifulN oxVs of Nature, A Fleas ^ Mitts ^ Gnats to anHorfesan Ele- phants or a Lyon* \ SOME I *.^xZ V.'Rtr «fll> *ij*> •> CW- ^5.45 143242 C43 T|GrT.fS''5r« ^ ^ ^ '»s«' <^ *-T^ ‘'i** ^ *-3^ * 3 >» M I C R O G R- A P H I A, OR SOME Phyfiological Defcriptions M I N U T E B O D I E S MADE BY magnifying GLASSES; . WITH Observations and I n q_u i R i e s thereupon. Obferv. I. Of the Point of a Jharp fmallNeedki S i'n Geometry^ the moft natural way of beginning is Sehem.26 from a Mathematical ^ ib is the fame method in Fig.io Obfervations and Natural hijiory the moft gcnuinCjlim- ple, and inftruftive. We muft firft endevour to make letters^ and draw fugle ftrokes true , before we ven- ture to write whole Sentences , or to draw large Pi- Bures. And in Phj/fcal Enquiries, we muft endevour to follow Nature in the more plain and eafe ways fhe treads in the moft ^mple 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 fhe has in bodies of a more complica- r(?<3f nature 5 left, being unable todiftinguilh and judge of our way, we quickly lofe both Nature our Guide,and our felves too.and are left to wan- der in the labyrinth of groundleft opinions 5 wanting both judgment^ that lights and experience^ that c/era?, which fhould diredb our proceedings. We will begin thefe our Inquiries therefore with the Obfervations of Bodies of the moft fmple nature firft,and fo gradually proceed to thole of a more compounded one.in profecution of which method,we fhall begin with a Thyfcal point-^ of which kind the Point of a Needle is commonly reckon’d for one , and is indeed, for the moft part, made fo lharp, that the naked eye cannot diftinguilli any parts of it : It very eafily piercesj and makes its way through all kind of bodies fofter then it felftBut if view’d with a very good Microfcope^ we may find that the top of a Needle (though as to the B fenfe Micrographia. fenle very J/jarp) appears a Iroadjflnnt^ and very irregular etid j not referh-’ 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 ib great a (harpnefs ^ how much therefore can be built upon demonftraticns made onely by the productions of the Ru- ler and Compafles, he will be better able to confider that fliall but view thofe points and lines with a Microfcope, Now though this point be commonly accounted the fharpeft (whence when we would exprcfe the fharpnels of a point the moft jitperlatively^ we fay. As (harp as a Needle) yet the Microfcope can afford us hundreds of In- ftances of Points many thoufand times Iharper : fuch as thofe ofthe^^ir/, and brijilesy and claros of multitudes of Infect 5 the thorns , or crooks^ or hairs of leaves^ and other fmall vegetables 3 nay, the ends of the Jiiri(e or finall parallelipipeds of Amiatithns , and alumen plnmojitm 3 of many of which, though the Points are fo (harp as not to be vifible, though view’d with a Microfcope (which magnifies the ObjeCl:, in bulk, above a million of times) yet I doubt not, but were we able praBically to make Microfcopes according to the theory of them, we might find hills, and dales,and pores, and a lufficient bredth, or expanfion, to give all thofe parts elbow-room, even in the blunt top. of the very Point of any of thefe fo very fharp bodies. For certainly the qttantity or extenfion of any body may be Divif ble 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 fmall and very ftiarp Needle, whofe 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 3 fo 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 on ei- ther fide. The furface of which, though appearing to the naked eye very fmooth,could not neverthelefs hide a multitude of holes and feratches and ruggedneffes from being difeover’d by the Microfcope to inveft it, feveral of which inequalities (as A,B,C, feem’d holes made by fbme fmall fpecks of Rujl 3 and D fbme adventitious body^ that ftuck very clofe to it) were ca- Jual. All the reft that roughen the furface, were onely fb many marks of the rudenefsand bungling of Art. So unaccurate is it, in ail its producti- ons, even in thofe which feem moft neat, that if examin’d with an organ more acute then that by which they were made, the more we fee of their jhape^ the lefs appearance will there be of their beauty : whereas in the works of Nature^ the deepeft Difeeveries fhew us the greateft Excellen- cies. An evident Argument, that he that was the Author of all thefe things, was no other then Omnipotent 3 being able to include as great a va- riety of parts and contrivances in the yet fmalleft Difeernable Point, as in thofe vafter bodies (which comparatively are called alfo Points) fuch as the Earthy Sun^ or Planets. Nor need it feem ftrange that the Earth it felf may be by ^nAnalogie call’d aThyfical Point:For as its body, though now 3 MiCROGP. APHIA. lb near US as tofilloureys and fancies with a fenleof the vaftncls of it, may by a little Difiance, and fome convenient DimittiJInng Glafles, be made vanifh into a fcarce vifible Speck, or Point (as I have often try’d on the and (when not too bright) on the Sun it felf.) So, could a Mechanical contrivance fuccesfully anlwerour iheory^ we might fee the leaft fpot as big as the Earth it ielf 5 and Difcover, as Des Cartes Dief- ck alfo con jedures, as great a variety of bodies in the or Vianet s^ as in ^ 5 the Earth. But leaving thefe Difcoveries to future Induftries, we (hall proceed to add one Obfervation more point commonly fo Call’d, that is, the mark of zpiU jtop. or period. And for this purpofe I obferved many bothprinted ones and written ^ and among multitudes I found /in? 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 disfigur’d'^ and for the moft part if they feem’d equally round to the eye, I found thole points that had been made by a Copper-plate^ and Roll-prels, to be as mislhapeft as thofe which had been made with Types ^ the moR curious andfmothly engraven Jirokes and points^ looking but as fo many furrows and holes ^ and their printed imprejfions, but like fmutty daubings on a matt or uneven floor with a blunt extinguilht brand or ftick’s end. And as £or points made with zpen they were much more rugged and deformed. Nay,having view’d certain pieces of exceeding curious writing of the kind ( one of which in the bredth of a two-pence compris’d the Lords prayer^ the Apojlles Creed^ the ten Commandments^ and about half a dozen verfes befides of the Bible^ whofe lines were fo fmall and near together^ that I was unable to number them with my nakgd eye^ a very ordinary Microfope^ I had then a- bout me,inabled me to fee that what the Writer of it had aflerted was true^ but withall difoover’d ofwhatpitifull bungling fcribbles and (crawls it was compos d^Arabi an and China characters being almofi: as well fhap’d 5 yet thus much I muft fay for the Man, that it was for the moft part legible enough, though in ibme places there wanted a good fantjy well prepojeji to help one through, if this manner oi fmall writing were made efiie and praBicable ( 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 eafi^ and accurately enough in a very little roome ) it might be of very good ufo to convey fecret Intelligence without any danger of Difcovery or mijirujiing. But to come again to the point, 'thclrregularities oh\t are caufed by three or four coadjutors^ one of which is, the imeven furfacc oC the paper ^ which at belt appears no Imother then a very courfo piece of jhagd cloth^ next the irregularity of the Type or Ingraving.^ and a third is the rough Daubing of the Printing-Inkthat lies upon the inftrument that makes the impreflion, to all which, add the variation made by the Different lights and fijadows^ and you may have fufficient reafon to ghels that a peint may appear much more ugly then thk^ which I have here prefented, which though it appear’d through the Microfeope gray^ like a great Iplatch of London dirt, about three inches over 5 yet to the naked eye it w^asblacf^ and no bigger then that in the midft of the Circle A. And could I have found 4 Micrographia. found Room in this Plate to have inferted an O you Ihould have feen that the letters were not more diftind then the points of Diftindion, nor a drawn circle more exadly Jb^thcn vve have now (hown a point to be zpeint. Obferv. II. Of the Edge of a Razor. Schtm. 7 . ^■r’'He fharpeft Edgehzth. thelame kind of affinity to the fharpeftPw^t -f’X- 2. J in Phyficks, as a line hath to apoint 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- fpetl:, till more clofely viewed by the Microfeope^ and there we may ob- ferve its very Edge to be of all kind of fliapcs, except what it Ihould be. For examining that of a very (harp one, I could not find that any part of it had any thing of fliarpnefs in it 5 but it appear’d a rough forface of a very confiderable bredth from fide to fide, the narrowed part not leem- ing thinner then the back of a pretty thick Knife. Nor is’t likely that if ftiould appear any otherwife, fince as we juft now (hew’d that a point ap- pear’d a circle^ ’tis rational a line ftiould be a parallelogram. Now for the drawing this fecond Figure( which reprefents a part of the Edge about half a quarter of an inch long of a Razor well fet) I ilb plac’d it between the Objed-glals & the light, that there appear’d a refledtion from the very Edge,repreiented by the white line abode fin which you may perceive it to be fomewhat ftiarper then elfewhere about dy to be indent- ed or pitted about by 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 hi fmooth as one would imagine lb Imooth bo- dies as a Hone and Oyl Ihould leave it 5 for befides thole multitudes of Icratches, which appear to have raz’d the furface ghik^y and to crols each other every way which are not half of them expreft in the Figure, there were leveral great and deep Icratches, or furrows, fuch zs gh and i k.y which made the furface yet more rugged, caus’d perhaps by Ibrae finall Duft cafually falling on the Hone, or Ibme harder or more flinty part of the Hone it lelf The other part of the Razor / /, which is polilh’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 lhall we wonder at the roughnefl'es of thofe furfaces , fince even in the moft curious wrought Glaflesfor Microfeopesy and other Optical ufes, I have, when the Sun has fticne well on them , dilcover’d their liirfacc to be varioully raz’d or lcratched,and toconfiftofan infinite of Imall broken liirfaces, which re- fledc the light of very various and differing colours. And indeed it leems impolfible by Art to cut the liirface of any hard and brittle body fmooth, fince VtittCy or even the moft curious Powder that can be made ufe of, to polifli liich a body, muft confift of little hard rough particles, and each of them muft cut its way, and conlequcntly leave Ibme kind of gutter or furrows . 5 Micrographia. furrow behind it. And though Nature does fcem to do it very readily m all kinds of fluid bodies , yet perhaps future obfervators may difcover even thcfe alfo rugged 5 it being very probable, as I elfewhere (hew, that fluid bodies are made up of fmall folid particles varioufly and llrongly mov’d, and may find reafon to think there is fcarce a furface in rerttm na* tura perfedly 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 cTCorrofiveJuyces. To conclude, this Edge and piece of a Razor, if it had been really fuch as it appear’d through the Microfcope^ would fcarce- ly have ferv’d to cleave wood, much lefs to have cut off the hair of beards, unlefs it were after the manner that Lncian merrily relates to have made ufe of, when with a Carpenters Axe he chop’d off the beard of a lage Philofopher, whofe gravity he very cautioufly fear’d would indanger the overfetting of his Wherry. Obferv. III. Of fim Lawn^ or Limen Cloth. T His is another produd of Art, A piece of the fineft Lawn I was able to get, fo curious that the threads were Icarce dilcernable by the na- ked eye,and yet through an ordinary Mkrofcope you may perceive what a goodly piece of coarfe Matting it is 5 what proportionable cords each of its threads are, being not unlike, both in fliape and fize, the bigger and coarfer kind of J/»^/e2J(?fe-_;', /», /», fhould appear (hadowed, or dark^ why feme, as (hould appear partly light,and partly dark : the varieties of which reflexions and Ihadows are the only caufe of the appearance of wa- tering in Silks, or any other kind of Stuffs. From the variety of refleXion, may alfo be deduc’d the caule why a finall breez or gale of wind ruffling the liirface of a fmooth water, makes it appear black , as alfo,on the other fide, why the fmoothing or burnifli- ing the furface of whitened Silver makes it look black 5 and multitudes of other phenomena might hereby be folv’d, which are too many to be here infifted on. Obferv. VI. Of [mail Glafs Canes, T Hat I might be (atisfi’d, whether it were not poflibleto make an Artificial pore as fiftall as any Natural I had yet found, I made fe- veral attemps with final! glajs pipes^ melted in the flame of a Lamp, and then very juddenly drawn out into a great length. And, by that tneans^ without much difeculty, I was able to draw fome almoft as finall as a Cobweb:, which yet, with the AficroJcopC:, I could plainly perceive to be perforated:, both by looking on the euds of it, and by looking on it agamji the light 5 which was much the eajier way to determine whether it were Iblid or perforated 5 for, taking a finall pipeofglafi, and clofing one end of it, then filling it half full 2 LV\dho\dmg\t agawjl the lights I could, by this means, very eafily find what was the clifieriug ajpe& of a Jolid and a perforated piece of glafi 5 and fb eafily diltinguifh, without feeing either end, whether any of glafs I look’d on, were a. Jolid fiick^:, or a hollow cane. And by this means,! could alfb prefently judge of any finall 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 ule 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 of look- ing on, or viewing the ObjeX. For, if we confider firft,the very faint light wherewith the objeX is enlightened, whence many particles zy’' YGZX opacous:, which when more enlightned, appear very lb that I was fain to determine its tranjparency by one glals, and its texture by another Next, the unmanageabknefs of moft Obje^s^ by realbn of MlCROGRAPHIAi l£ o£thdtfiialnefiy 5. The difficulty of findihg the defired point, and of placing it fo, as to refied the light conveniently for the Inquiry, Laftly, ones being able to view it but with one eye at once, they will appear no finall obflu 0 ions^ nor are they eafily removd without many contrivan- ces. But to proceed, I could not find that water, or fbme deeply tingd liquors would in filiall ones rife fo high as one would exped 5 and the highefl I have found it yet rife in any of the pipes I have try’d. Was to 21 inches above the level of the water in the veflel ; for though I found that in the fmall pipes it would nimbly enter at firft, and run about 6 or 7 upwards^ yet I found it then to move upwards^^ 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 Tipe^ in comparifon of thofe I for- merly mentioned , for I could oblerve the progrejs of a very deep tingd liquor in it with my naked eye^ without much trouble 5 whereas many of the other pipes Ycexeio very fmaU.^ thatunlefs in sl convenient pojiure to the light, I could not perceive them :) But ’tis very probable, that a greater patience and ajpduity may difcover the liquors to rife^ at lead to remain fufpcnded.j at heights that I fhould be loath now even to ghefs at, if at lead: thexehe 2Lny 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 Expertmeni, My Conjedure, ’That the unequal height of the Jurfaces of the water ^ proceeded from the greater prejjure made upon the water by the Air f without the Pipes ABC, then by that within them ^ I (hall endeavour to confirm from the truth of the two following Propoftions : The firfl: of which is. That an unequalprefure of the incumbent Air^ will caufe an unequal height in the water s Surfaces. And the fecond is. That in this experiment there is Juch an unequal prefure. That the firft is true^ the following Experiment will evince. For if you take any Veflel fo contrived, as that you can at pleafure either in- creafe or diminif the prefure 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 h^loji-^ and that part of th.Q Superficies t\nt{\x{i2\nsxhQ greater f ref fire, will be inferior to that which undergoes the lefs. A fit Veflel for thispurpofe, will be an inverted Glafs , and the bubbles of air which are by any means conveyed under the forface of the water 5 or a drop of common Sallet Oyl fwimmingupon water. In all which, and many more examples of this kind that might be enumerated, the incongruity of two fluids is eahly dilcernable. And as for the Congruityox Incongruity of Liquids, with feveral kinds oijirm Bodies, they have long fince been taken notice of, and called by the Names of Drinefs and Moiflure (though thefe two names are not compre- henfivc enough, being commonly ufed to fignifie only the adhering or not adhering of water to fome other folid Bodies)o£ this kind wemay ob- (erve that water will more readily wet Jomc woods then others and that water^ let fall upon a Feather^ the whiter fide of a Colwort^ and fome other leaves. Or upon almofl: any unUuous^ or reftnous {u^erdcies will not at all adhere to them, but eafily tumble ojf fi om them, like a I'olid Bowl 5 whereas, ifdropt upon Linnen, Paper ^ Clay^ green Wood^ 8cc. it will not be taken off, without leaving fome part of it behind adhering to them. So ^ickfllver^ which will very hardly be brought to flicks 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, Firll:, what is the caufe of fluidnefs 5 And this, I conceive^ to be nothing elfe but a certain pulfe or Jhake oiheat ^ for Heat being nothing elfe but a very bris kjar^d ve- hement agitation of the parts of a body (as I have elfwhere made proba- bable) the parts of a body are thereby made fb 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 fuppofe a difh of fand fet upon fome body that is very much and fhaken with fome quiche and firong vibrating motion^as on a Milflone turn’d round upon the under ffone very violently whilfl it is empty^or on a very fl:iffDm«?-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 dull and nnadive body, be- comes a iperiedi fluid '■) and ye cannofooner make a hole in it with your finger, but it is immediately //W up again^ and the upper furface of it leveU 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 3 nor can you lay a on the top of it, as a piece of Lead, but it is immediately buried in M, I CROGRAPHIA* in Sandj and (as^tvvere) finks to the bottom. Nor can you make a hok in the fide of the Difli, but the land (hall run out of it to a levels not an obvious property of a fluid body, as fuch, but this dos imitate 3 and all this meerly caiued by the vehement agitation of the conteining veflel 5 for by this means, each (and becomes to have a vibrative or dancing mo* tion, (b as no other heavier body can reji on it, unlels Jufieind by (bme Other on either fide : Nor will it differ any Body to be beneath it, unlefs it be a heavier then it felfl Another Inftance of the (f range loofening nature of a violent jarring Motion, or a ftrong and nimble vibrative one, we may have from a piece of iron grated on very ftrongly with a file : for if into that a pin be fcrexdd (b firm and hard, that though it has a convenient head to it, yet it can by no means be unfcrevpd by the fin* gers ^ if, I fay, you attempt to unlcrew this whilft grated on by the file^ it will be found to undoe and turn very eafily. The firfl: of thel'e Examples manifefl s, how a body adually divided into fmall parts, becomes a fluidi 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 (up* pofe heat to be any thing elfe, befides fuch a motion 5 for fuppofing we could Mechanically produce (uch a one ^«ic^and Jirong enough, we need not fuel to melt a body. Now, that I do not (peak this altogether groundleis, I muft refer the Reader to the Obfervations I have made up- on the (hining fparks of Steel, for there he (hall find that the fame effeds are produced upon fmall chips or parcels of Steel by the flame^ and by a quicks and violent motion ^ and if the body of feel may be thus melted (as I there (hew it may) I think we have little realbn to doubt that al* moft any other may not al(b. Every Smith can inform one how quickly both his File and the Iron grows hot with filing^ and if you rub almoft any two bodies together, they will do the (ame : And we know, that a fufficient degree of heat caufes fluidity^ in (bme bodies much (bon- er, and in others later 5 that is, the parts of the body of (bme are (b Icoje from one another, and (b unapt to cohere, and (b minute and little, that a very^4// degree of agitation keeps them always in the fate of fluidity. Of this kind, I (iippole, 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 tinBure or folution of ter- reftrial and aqueous particles into it, and agitated by it, jufl: as xd\o.tinBureoiCocheneel\% nothing but (bme finer dfloluble parts of that Concrete lick’d up or dijjolvd by the fluid water. And (rom this Notion of it, we may eafily give a more Intelligible reafon how the Air becomes (b capable oi RarefaBion and Condenfation. For, as in tinBures,onQ grain of (bme flrongly tinging fubftance may fenflbly colour (bme hundred thou- fand grains of appropriatedV\cpjLOxs,{o as every drop of it has its proportio- nate (hare, and be fenfibly ting’d, as I have try’d both with Logtoood and Cocheneel : And as fome few grains of Salt is able to infed as greataquantity,as may befoundby/jr^f^^z^d/zf/^j-, though not (b eafily by the fight or afle 5 (b the Air, which feems to be but as ’twere a tinBure or faline Jubfiance, diJ[olvd and agitated by the fluid and agil A£theryxizy dff Micrograp hia. perfe and expand it felf into a vajl Jpace^ if it have room enough, and infed,as it were,every part of that fpace. But, as on the other fide, if there be but Come f erf graws of the liquor, it may extraB all the colour of the tinging fubftance, and may dijjblve all the Salt, and thereby become much more impregnated with thofe fubftances, fo may all the air that luf^ ficed ina rarifyd (iate to fill fome hundred thoufaud fpacesof i^!ther, be compris’d in only one^Mt in a pofition proportionable denfe. And though we have not yet found out fuch firainers for Tinftures and Salts as we have for the Air, being yet unable to feparate them from their diflblving liquors by any kind oifiltre^ without precipitation^ as we are able to fe^ parate the Air from the ^ther by Glafs^ and feveral other bodies. And though we are yet unable and ignorant of the ways of precipitating Air out of the Aither as we can Tindtires, and Salts out of feveral dijjblventsi, yet neither of thefe fceming impojjible from the nature of the things, nor fo improbable but that fome happy future induftry may find out ways to effcd them 5 nay, further, fince we find that Nature does really perform (though by what means we are not certain) both thele adcions, namely, by precipitating the Air in Rain and Dews, and by fopplying the Streams and Rivers of the World with frefh water, flraind through lecret fiib- terraneous Caverns; And fince, that in very many oth.tr proprieties they do fo exaftly 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 prediB what is likgly to happen in other particulars alfo, befides thofo which Obfervation or Experiment have declared thus or thus 5 elpecially, if the circum- fiances that do often very much conduce to the variation of the efiedls be duly tveigh’d and conjiderd. 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 produBs of chance^ and not of Reajbn 5 and, like Mariners in an Ocean, deftitute both of a Compafs and the fight of the Celefiialguids^ we might indeed, by chance^ Steer direBly towards our defired Port, but ’tis a thoufand to one but we mife our aim. But to proceed, we may hence alfo give a plain reafon, how the Air comes to be darkled by clouds^ 6cc. which are nothing but a kind of precipitati* on^ and how thofe precipitations fall down in showrs. Hence alfo could I very eafily, and I think truly, deduce the caufe of the curious (ixangu* lar figures of Snow, and the appearances of Haloes^ d^c. and the ludden thickgiing of the Sky with Clouds, audthe varnfijing and dijappearing of thole Clouds again 5 for all thele things may be very eafily imitated in a glafsof liquor ^\td\ fome iWght 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 confiftof particles more Crofi^ and of a more apt figure for cohefion^ and this re- quires agitation , fuch, I fup^ofe fermentedvinous Spirits M I C ROG R A P H I A» Spirits, feveral Chjimical Oils, which are much of kin to thofe Spirits, &c< Others yet require 2i greater, as water, and fo others much greater, for al- moft infinite degrees: For, I fuppofe there are very /w bodies in the world that may not be made alicptatemis fluid, by [ome or other degree of agitation or heat. " Having therefore in fhort fet down my Notioil of a Fluid body, I cotne in the next place to confider what Congruity is 5 and this, as I faid before, being a Relative property of a fluid, whereby it may be faid to be like or ttnlike 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 former Experi- ment, though but a rude one , and here if we mix in the dSHhfeveral kiisdi of lands, fome oi bigger, others of lefs and finer bulks, we fhall find that by the agitation the fine /and will eje& and throw out of it felf all thofe bulks of {m2i\\jiones and the like, and thofe will be toge- ther all into one place 5 and if there be other bodies in it of other natures, thofe alfb will hcfeparatedmio a place by themfelves, and unitedoxtum- hledw^ together. And though this do not come up to the higheji proper- ty of Congruity, which is a Coh^fion of the parts of the fluid together, or a kind of attraBion and tenacity, yet this does as ’twere fi?adow it out, and fbmewhat relemble it, for juft after the fame manner, I fuppofe the of heat to agitatet\iQ fmall parcels of matter, and thofe that are of a like bignef, 2X\d figure, and matter, will hold, or dance together, and thofe which are of a differing kind will be thruji or Jhovd oUt from be- tween them^ for particles that are all fimilar, willj like fb mzny equal ntufical firings equally firetcht, vibrate together in a kind of Harmony or nnifon , whereas others that are diffimilar, upon what account fbever,un- lefsthe difproportion be othcrwife counter-ballanc’d, will, like fbmany firings out of tune to thofe unlfons, though they have the fame agitating pulfe, yet make quite diff^ering kinds of vibrations and repercuffions, fb that though they may be both mov’d,yet are their vibrations {o dijferent,and fo untun d, as twere to each other, that they crofs and jar againft each other, and confequently, cannot agree together, but fly back^itom each other to their fimilar particles. Now, to give you an inftance how the difproportion of fome bodies in one refpeft, may be counter-ballunc 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 bignefs, length, and tenfion, or by two firings of the fame bignefi, but of differing length,zr\d 2 l contrary differing tenfion', or fiy. by two firings of unequal length and bignefi, and of a differing tenfion, or of equal length, and diffe- ring bignefs and tenfion, and leveral other flich varieties. To which three properties in firings, will correfpond three proprieties alfo in find, or the particles of bodies, their Matter or Subfiance, their Figure or shape, and their Body or Bulk. And from the varieties of thefe three, may arife in- finite varieties in fluid bodies, though all agitated by theyS^ze pulfioxvi- brative motion. And there may be as many ways of making Harmonies Micrographia. and Difcords with thcfe, as there may be with mujical firings. Having therefore Icen what is the caufe of Congruity or Incongruity, thofe rela- tive properties of fluids, we may, from what has been laid, very eafily collect, what is the of thofe Relative proprieties alfo between flu^ id bodies andjolid ^ for lince all bodies confift of particles of fuch a Sub- fiance^ Figure^ and Bulkj) but in Ibme they are united together more firm- ly then to be loofined from each other by every vibrattve motion (though I imagine that there is nobody in the world, but that Ibme degree of a- gitation may, as I hinted before, agitate and loolcn the particles fo as to make them fluid) thole cohering particles may vibrate in the fame man- ner almofl: as thofe that are loofe and become unijbns or difcords^ as I may lb fpeak, to them. Nowthatthe/?^r/j-of all though never fb folid^ do yet vibrate^ I think we need go no fnrther for proof, then that ^/('bodies have Ibme of in them, and that there has not been yet found any thing perfeidly cold: Nor can I believe indeed that there is any fuch thing in Nature, as a body whofe particles are at or lazy and unaBive in the great Theatre of the Worlds it being quite contrary to the grand Oeconomy of the Univerle. We fee therefore what is the rea- fon of the Jympathy or uniting of fome bodies together, and ol the anti- pathy or flight of others from each other : For Congruity feems nothing elfe but a Sympathy^ and Incongruity an Antipathy of bodies ^ hence fimi- lar hoddes once united w\\\ not eafily part and dijfimilar bodies once difi joyndwill not eafily unite again ; from hence may be very eafily deduc'd the realbn of ihe/ujpenfion ob water and ^ickfilver above their ufual fia- //i.c. and unite with them : but roul off from Woodj Stone^ Glafs^ 8cc. if never lb little feituated out of its horizontal le^ veli^ and water that will wet fait and dijjblve it, will firp off from Tallow^ or the like, without at all adhering ^ as it may likewife be obferved to do upon a dufiy luperficies. And next they caule the parts of homogene- al fluid bodies readily to adhere together and mix^ and of heterogenealyo be exceeding averfe thereunto. Hence we find, that two fmall drops of water ^ on any luperficies they can roul on, will, if they chance to touch each other, readily unite and mix into one drop : The like may be ob- fexvedWithtwohtnaWBowlsob ^ithcfdver xi^on a Table or Glafs, pro- vided their furfaces be not ^ and with two drops of oy upon fair water, (fic. And further, water put unto wine^falt water ^ vinegar^ fii^B of or the like, does immediately (efpecially if they be fhaken to- gether) dijperje it lelf all over them. Hence, on the contrary, we allb find, that Oyl ofTartarp^onxed upon g^ickcftlver^ and Spirit of Wine on that Oyf and Oyl of Turpentine on that Spirit^ and Air upon that C^/,though they beftopt clofely up into a Bottle, and fijaken. never fo much, they will by no means long fufter any of tlieir bigger parts to be united or in- cluded MiCROGRAP HiA. eluded within any of the ether Liquors'(by which recited Liquors, may he plainly enough reprefented the four Peripatetical Elements^ and the more fubtil j¥.ther above all.) F rom this property’tis, that a drop of vpater does not mingle with, or vanilh into Air^ but is driven (by that Fluid equally protruding it on every fide) andforc’t into as little afpace as it can pofi fibly be contained in, namely, into a RQund Globule. So likewife a lit” tie Air blown under the rvater^ is united or thruft into a ^bble by the ambient water. And a parcel of ^ickcfdver enclofed with Air^ Water ^ or almoft any other Liquor., informed into a round Ball. Now the caufe why all thefe included Fluids, newly mentioned, or as many others as are wholly included within a heterogeneous fiuid, are not exaH ly oi 2. Spherical Figure (feeing that if caufedby thefe Principles only, it could be of no other) muft proceed from fome other kind of preffure againfi: the two oppofite flatted fides. This ad.ventiuons or acci- dental prej^ure may proceed from divers taujes, and accordingly muft di- the Figure of the included heterogeneous fluid : For feeing that a body may be included either with 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 Jurfaces, much differing from a Spherical^ according to the vari- ous refiftance or preffure that belongs to each of thefe encompaffing bo- dies. Which Properties may in general be deduced from tv/o heads , viz. Motion^ and ReU. For, either this Globular Figure is altered by a natu- tal Motion^ fuch as is Gravity 5 or a violent ^ fuch as is any accidental motion of the fluids, as we fee in the itcind ruffling up the water, and the purlings of Streams^ 2nd foaming oiCatarraBs^ and the like. Or thirdly. By the Refl^ Firmnefs 2nd Stability oi the ambient Solid. For if the including Solidbo of an angular or any other irregular Form, the included fluid will be near of the likeyis a Pint-r^^t full of water ^ot a Bladder full of Air. And next, if the including or included fluid have a greater one than another,then will the globular Formbedepreft into 2n Elliptico-fpherical ; As if, for example, we fuppofethe Circle A B C D^in the fourth Figure.^ toxe^xe(ent2drop of roater, g^ick^filver., or the like, included with the Air or the like , which fuppohng there were no gravity at all in either of the fluids^ or that the contained 2nd containingwete of the fame weighty would be equally comprefl into anexadly fphericalhodj ( the ambient fluid forcing equally againft every fide of it. ) But fuppofing either a greater^r4«/z>j' in the included, by realbn whereof the parts of it being preflfwm A towards 5 , and thereby the whole put into motion ^ and that motionhem^ kindred by the refiflance o£ the Jubjacent parts of the ambient, the globular Figure A D B C will be depreji into the Elliptico- jphericaly E G F H. For the fide ^ h detruded to E oy the Gravity , and B to F by the refiflance of the fiibjacent medium : and therefore C muft neceffarily be thruff to G5 and D to H. Or elle, fuppofing a greater ty in the ambient^ by whole more then oxddn2iy preflure againft the under lide of the included globule 5 B will be forced to F, and by its refiftance of E the Ml CROGRAPHiA. the motion upwards ^ the fide A will be depreji to £, and therefore C being thruft to G and D to H 5 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 fhaped diverjly , ac- cording to the proportion of the gravity and incongruity of the 3 jlftids one to another : As in the fecond Figure^ let the upper M AfMbe Air^the middle L M N 0 be common (^/, the lower 0 0 0 be fVater^ the Oyl will be form’d, not into a Figure, fuch as is reprefented by the pricked Line^ but into fuch a Figure as L M N O, whole fide L M N will be of a flatter £//7^/;^vt/Figure, by reafon of the great difproportion between the Gravity of Oyl and Air^ and the fide L O M of a rounder^ bccaufe of the fmaller difference between the weight of Oyl and Water, globular 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 fhap’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. Asfuppofethe fubjacent me^ dium that hinders an included fluids dcfcent,be a jblid , as let K I, in the fourth Figure^ reprefent the fmooth fuperficies of a Table 5 E G F H, a parcel of running Mercury 5 the fide G F H will be more flatted , ac- cording to the proportion of the incongruity of the Mercury and Air to the ^£ be 1. 4 X 6 X s X I a > A *4 i 3 » of an inch. There may be added as many more , as the Experimenter lhall think lif^ with holes continually decreafing by known quantities, fo far as his fenfes arc able to help him , I fay, lb far, becaufe there may be made Pipes fo (mall that it will be impolTible to perceive the perforation with ones na- ked eye, though by the help of a Microfeope, 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, inlbmuch that I have been able to knit it up into a knot without breaking : And more accurately examining one with ray Microfiope, I found it not lb big as a fixteenthpart of one of the Imaller hairs of my head which was of the fmaller and finer Ibrt of hair, fo that lixteen of thefe Pipes bound fag- got-wile together, would but have equalized one Angle hair, how Imall therefore mufl: its perforation be ? Ft appearing to me through the Micros- fcope to be a proportionably thickfided Pipe. To proceed then, for the trial of the Experiment , the Experimenter mufl 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 mufl oblerve diligently how high the water will rife in it before it protrude the bubble of Air C, through the narrow pallage of F, and denote exadly the height of the Cylinder of water , then cementing in a fecond Pipe as G, and filling it with water ^ he may proceed as with the former , denoting likewile the height of the of water , able to protrude the C through the paflage of G, the like may he do with the next Pipe^zndi the next,c^c. as far as he is able ; then comparing the leveral heights of the Cylinders^ with the leveral through which each Cylinder did force the f ha- ving due regard to the Cylinders of water in t\io fuiddlTubes) it will be very eafie to determine, what force is requifite to prels the Air in- to luch and luch#* hole^ or (to apply it to our prelent experiment J how M I C R O G R A P H I A. 21 how much of the preflure of the Jir is taken off by its ingrefsinto fmal- ler and fmaller holes. From the application of which to theentririgof the Air into the bigger of th^VeJJel^ and into the fmaller of the Pipe^ we fhall clearly find, that there is a greater preffure of the air upoti the water in the Vejjelor: greater pipe, then there is upon that in the leffer pipe: For fincethe preflure of the air every way is found to be equal, that is, as much as is able to prefs up and fuftain a Cylinder of gpuicksiher of two foot and a half high, ot thereabouts j 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. And laftly, fince thofe degrees that are requifite 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 tht tvater therein, then the Air in the bigger : which was the minor Propofition to be proved. The Conclufion therefore will neceflarily follow, viz. That this une^ qnalprefsiire of the Air caufed by its ingref into unequal holes, is a caufe fuffi- dent to produce this effeCl , without the help of any other concurrent \ and therefore is probably the principal (if not the only) caufe of thefe Vh^no- mena. ■ ^ This therefore being thus explained, there will be ^wtrsPheenometta explicable thereby, as, the riling of Liquors in a Fibre, the rifing of Spirit of Wine, Oyl, melted Tallow, &c. in the Week^ of a Lamp, ( though made of fmall Wire, Threeds of Asbeflus, Strings of Glafs, or the like ) the rifing of Liquors in a Spunge, piece of Bread,Sand, d^c. perhaps alfo the afeend-^ ing of the Sap in Trees and Plants, through their fmall, and fbme of them imperceptible pores, (of which I have faid more, on another occafion ) at leaft the palling 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- curred to me, which I have not yet fo well examined and digefted as to propound for Axioms, but only as ^erics ^ndConje^tures which may forve as hints toward fome further difeoveries. As firfl, Upon the confideration of the congruity eniA incongruity of Bo- dies, as to touch, I found alfo the like congruity and incongruity Q if I may fo fpeak ) as to the Travfmitting of the Raies of Light ; For as in this re- gard, f not now to mention other Liquors ) feems, nearer of affini- ty to Claf^ then ^z>,and Air then g^mcksilver : whence an oblique Ray otit of Glafs, will pafs into water with very refraction from the perpendi^ cular, but none out of Glafs into Air, excepting a dire&, 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 ^fo^- will neither admit oblique or direct, butrefledsall 5 feeming,as to the tranfmitting of the Raies of Light , to be of a quite differing confli- tution,from that of Air, Water, Glafs, dAc. and to refemble mofl: thofe opa- cousand ftrong refleding bodies of Metals ; So alfo asto the property of cohefion or congruity , Water feems to keep the fame order , being more 22 Micrographia. more congruous to Glafs then Air , and Air then Quickfilver. A Second thing ( which was hinted to me, by the confideration of the included fluids globular form , cauled by the protrufion of the ambient heterogeneous fluid J was, whether the Vh£n 0 me? 7 a of gravity might not by this means be explained,by fuppofing the Globe of Earth, Water, and Aar to be included with a jluid^ heterogeneous to all and each of them, ib fubtil 3 as not only to be every where inter]} erfed through the Air^ ("or rather the air through it J but to pervade the bodies of Glafs , and even the clofejl Metals^ by which means it may endeavour to detrude all earth- ly bodies as far 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 Ibme foch fluid,I could produce many Experiments and Rea- Ibns , that do leem to prove it ; But becaufe it would ask fome time and room to fet them down and explain them, and toconfiderandanfwer all the Objedions f many whereof I forefee J thatmay bealledged againfl: it 5 1 (hall at prelent proceed to other ^er/(e/,contenting my lelf to have here only given a hint of what I may lay more ellwhere. A Third ^erj/ then was , Whether the heterogeneity of the ambient fluid may not be accounted a fecondary canfe of the roundnefs or globular formoi tht greater bodies the world,fuch as are thole of th& Sun^Stars, and Planets^ the fubfance o£ each ofwhich feems altogether ous to the circum-ambient fluid wherefore the proportion of the gravity of thele two Liquors was as GHtoFE. This Experiment I tried with feveral other Liquors, and particularly with frelh Water and Salt ( which I made by diftolving 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 Experb 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 frelb was rather more then left 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 4^1045. that is, 46. Ounces of the fait Wa= "'FK ter 26 Micrographia. 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 frefli. But I found the proportion of Brine to frelh Water to be near 13 to 12: 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 frrained , lb 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 vSalt-water G M make the Cylinder of Frelh-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 meafiired then the height of the Mountains above it ; Tis enough for me to fay, there is no one of thole that have aflerted it , have experiment tally known the perpendicular of either 5 nor lhall I here determine, whe- ther there ma)^ not be many other caules of the leparation of the frefh water from the lalt , as perhaps fome parts of the Earth through which it is to pals , may contain a Salt , that mixing and uniting with the Sea-falt, may precipitate it ^ much after the lame manner as the Alkalizate and Acid Salts mix and precipitate each other in the preparation of Tarta- rum Vitriolatum. I know not alfo whether the exceeding cold (that mull: neceflarily be ) at the bottom of the Water, may not help towards this leparation , for we find , that warm Water is able to dillblve and contain more Salt , then the lame cold 5 infomuch that Brines ftrongly impregnated by heat, if let cool, do fuller much of their Salt to fubfide and cryftallize about the bottom and fides. I know not allb whether the exceeding prefliire of the parts of the Water one againft another, may not keep the Salt from defeending to the very bottom, as finding little or no room to inlert it lelf between thole parts , protruded lb vio- lently together , or elle Iqueeze it upwads into the luperiour parts of the Sea, where it may more eafily obtain room for it felf, amongfi: the parts of the Water, by realbn that there is more heat and lelsprefiure. To this Opinion I was Ibmewhat the more induced by the relations I have met with in Geographical Writers^ of drawing frelh Water from the bot- tom of the Sea , which is llilt above. I cannot now Hand to examine, whether this natural perpetual motion may not artificially be imitated : Nor can I Hand to anfvver the Objedions which may be made againft this my Suppofition ; As, Firfl, How it comes to pafs,that there arc fbmetimes lalt Springs much higher then the Superficies of the Water? And, Se- condly, Why Springs do not run faller 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, Inlhort, I fay, the frelh Water may receive again a- laline Tincture near the Superficies of the Earth , by palling through fome lalt or elle many of the faline parts of the Sea may be kept back, though not all. And M I C R O G R A P H I Ai And as to the Second , The fame Spr/f;gm2Ly be fed andfupplyed by divers Caverns, coming from very far diftant parts of the Sea , fo as that it may in one place be high , in another low water 5 and fo by that means the Spring may be equally lupply’d at all times. Or ehe the Cavern may be fo flraight and narrow , that the water not having fo ready and free padage through it^ cannot uponlo (hort and quick mutations of preflure, be able to produce any fenfible effed at fuch a diftance. Befides that, to confirm this hypotkefis^ there are many Examples found in Natural Hijio^ rianspf Springs that do ebb and flow like the Sea : As particuiarlyjthofe recorded by the Learned and after him by Speed^to be found in this Ijland: One of which^they relate to be on the Top of a Mountain, by the Imall Village Kilkgn in Flintjldre , Maris ^\{\ch. is ap- plicable to congruity^dnd confequently all the reft will be but fubfiquents: In the mean time I would not willingly be guilty of that Error the thrice Noble and Learned Vernlam juftly takes notice of, as fuchjand calls PhiloJbphir(?A:7>^^/dide , muft necefliirily move towards that part, from whence it finds leaft refiftance, and fo be accelerated^ as the re- liftance decreafes. Hence the more the water is raifed 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 lubftance to be moved at all, un- til it were placed uponlbme part of the Superficies that was fenlibly 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 exactly round Ball Upon a very fmooth fide of fome pliable body , as Horn or ^ickyilver^ For if the Ball be placed under a part of the Bladder which is upon one fide of the middle of its preflure , and you prefs ftrongly againft the Bladder,you (hall find the Ball moved from the middle towards the fides. Having go Micrographia. Having therefore fhewn the reafon of the motion of any float towards the (ides, the reafon of the incurfion of any two floating bodies will eafl- ly appear : For the rifing of the water againfl: the iides of either of them,is an Argument fufhcientjto (hew the preflure of the Air to be there lef$5then it is further from it5where it is not lb much elevated 5 and there- fore the reafon of the motion of the other toward it , will be the lame as towards the fide of the Glafs 5 only here from the lame reafon , they are mutually moved toward each other , whereas the fide of the Clals in the former remains fixt. If alfo you gently fill the Jar fo full with water, that the water hprotubera^t above the fides, the fame piece of Cork that before did haften towards the fides , does now fly from it as fall: towards the middle of the Superficies 5 the reafon of which will be found noo-^ ther then this, that the prelTure of the Air is ftronger againfl: the fides of the Superficies G and H, then againfl the middle 1 5 for fince, as I fhewed before, the Principle of congruity would make the terminating Surface Spherical , and that the flatting of the Surface in the middle is from the abatement of the waters preflure outwards, by the contrary indeavour of its gravity 5 it follows that the preflure in the middle muft be lefs then on the fides 5 and therefore the confecution will be the fame as in the former. It is very odd to one that conliders not the reafon of it , to fee two floating bodies of wood to approach earch other,as though they were indued with fome magnetical vigour 5 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 flick into the lame water, one part of the faid Cork would approach and make toward the flick, whereas another would difoede 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 flick, if let alone, it would inflantly turn its appropriate Pole toward it, and then run a-tilt at it:and this was done only by taking a dry Cork, and wetting one fide of it with one fmall flroak 5 for by this means gently putting it upon the water, it would deprels the fuperficies on eve- ry fide of it that was dry , and therefore the greatefl preflure of the Air, being near thofe fides caufed it either to chafe away,or elfo to fly oft from any other floating body, whereas that fide only, againfl which the water afeended, was thereby able to attraft. It remains only, that I fhould determine how high the Water or other Liquor may by this means be railed in a fmaller Pipe above the Superfi- cies of that without it , and at what height it may be foflained : But to determine this, will be exceeding difticult, unlefs I could certainly know how much of the Airs preflure is taken oft by the fmalnels of fuch and foch a Pipe,and whether it may be wholly taken off, that is,whether there can be a hole or pore lb fmall , into which Air could not at all enter, though water might with its whole force ^ for were there fiich , ’tis mani- fefl , that the water might rifo in it to fome five or lix and thirty Englilh Foot high. I know not whether the capillary Pipes in the bodies of fmall Trees, which we call their JUicrojcopical pores ^m^iy not be fuch 3 and whe- ther the congruity of the fides of the Pore may not yet draw the juyee even MiCROGRAPHlA. even higher then the Air was able by its bare prefiure to raife it : 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 ufual height. And this is obvious even in a drop of water fufpended under any Si- milar or Congruous body : For,befidcs the ambient prefiure that helps to keep it fiiftein d, there is the Congruity of the bodies that are contigu- ous. This is yet more evident in Tenacious and Glutinous bodies^ fuch as Gummous Liquors, Syrups, Pitch, and Rofin melted^ Tar, Tur- pentine, Balfom, Bird-lime, for there it is evident, that the Parts of the tenacious body, as I may fo call it, do ftick and adhere lb clofe- ly together, that though drawn out into long and very flender Cylin- ders, yet they will not eafily relinquifii one another y and this, though the bodies be aliquatetius fluid, and in motion by one another , which, to (itch as confider a fluid body only as its parts are in aconfuied irregu- lar motion, without taking in alfo the congruity of the parts one among another, and incongruity to fome other bodies, does appear not alittle ftrange. 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 may here a little further explain it ) is both a Tenaceous and an Attradive power ^ for the Congruity, in the Vi- brative motions,may be the caufe of all kind of attradion, not only Ele- drical, but Magnetical alfo, and therefore it may be alfo of Tenacity and Glutinoufnefs. For, from a perfect congruity of the motions of two diffant bodies, the intermediate fluid particles are foparated and dro- ven away from between them, and thereby thofe congruous bodies are, by the incompafling mediums, compelfd and forced neerer together y wherefore that attradtivenefs mufi: needs be ftronger, when, by an im- mediate contact, they are forc’d to be exadly the lame : As I fhew more at large in my ‘Theory of the Magnet. And this hints to me the reafon of the fufpenfion of the Mercury many inches, nay many feet, above the ulu- al ftation of 30 inches. For the parts of §yuick:^lver^ being fo very fimilar and congruous to each other, if once united, will not eafily fuffer a divulfion : And the parts of water, that were any wayes heterogemom^ being by exantlation or rarefaction exhaiifted, the remaining parts being alfo very firailar, will not eafily part neither. And the parts of the Glafr being folid, arc more difficultly disjoyn’d , and the water, being fome- what fimilar to both, is, as it were, a medium to unite both the Glafi and the Mercury together. So that all three being united, and not very difr fimilar, by means of this contad, if care be taken that the Tube in e- reCting be not (hogged, the ^icksilver will remain fufpended, notwidi-^ (landing its contrary indeavour of Gravity, a great height above its or- dinary Station , but if this immediate ContaCt be removed , either by a meer (eparation of them one from another by the force of a (hog, where- by the other becomes imbodied between them , and licks up from the (urface fome agil parts , and fo hurling them makes them air , or elfo 32 M I C R O G R A P H I A. byfome fmall heterogeneous agil part of the Water, or Air, orQiiick” filver, which appears like a bubble, and by its jumbling to and fro there is ' made way for xht heterogeneous Mther to obtrude, jt iel f betw een the Glafs and either of the other Fluids, the Gravity of Mercurj/ precipitates it downward with very great violence 5 and if the Vefl el thadiSld^ ^ 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 objefted, that it cannot be, that the meer imbodying of the jEther between thele bodies can be the caufe,fince the JEther ha- ving a free paffage alwayes , both through the Pores of the Glafs, and through thofe of the Fluids , there is no reafon why it fhould not make a leparation at all times whilft it remains fufpended, as when it is violently dif-joynedby a fhog. To this I anfwer. That though the ^ther Tpzffts between the Particles, that is, through the Pores of bodies, fo as that any chafme or feparation being made , it has infinite paflages 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 Mther 3 and thereby the parts of the congruous fubftances are feparated fb far afunder , that the ftrength of congruity is fo far wea- kened,as not to be able to reunite them, the parts to be taken hold of be- ing removed out of the attraCHve Sphere, as I may fo fpeak, of the con- gruity 3 fuch, I fay, is the tenacity of congruity, that it retains and holds the almoft contiguous Particles of the Fluid , and fuft'ers 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 railed a Steel pendulunthj aLoadftone to a great Angle, till by the fbaking 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 Tcndulum moves freely from it towards the other fide. So vaft a difference is there between the attractive vir- tue of the when it aCts upon a contiguous and upon a disjoyned body ; and much more muff: there be between the attraCrive virtues of congruity upon a contiguous and disjoyned body 3 and in truth the attra- ctive virtue is fb little upon a body disjoyned. that though I have with a Microfeope ohf^xvQdiVQxy diligently, whether there were any extraordi- nary 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:3 though I found, that as fbon as ever ittoucht it the whole drop would prefently unite it felf with it3 fb thatitfeems an abfolute con- taCl: isrequifite to the exercifing of the tenacious faculty of congruit)\ Obferv. Micrograp hi a. Obferv* VII. Of fome^hxnomend. of Glafs drop’s, ; '^HefeC/^ Drops are fmall [parcels of coarfe green Glals taken out of Jl the Pots that contain the Metal ( as they call it ) in fufioUj upon the end of an Iron Pipe 5 and being exceeding hot, and thereby of a kind of fluggifh fluid Confiftence, are fuffered to drop from thence into a Bucket of cold Water, and in it to lye till they be grown fenfibly cold. Some of thefe I broke in the open air, by fnapping off a little of the fmall Item with my lingers, others by crufhing it with a finall pair of PJy- ers 5 which I had no fooner done , 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 duff, 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 duff ^ thefe db fperfed every way fo violently , that fome of them pierced my skin. I 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 I nipt off whilft all the bodies, and ends of them lay buried under the water, which, like the former, flew all to pieces with as brisk a noife, and as ffrong a motion. Others of thefe I tried to break, by grinding away the blunt end^ and though 1 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 fiiap and fly off, not without a brisk noife and quick motion,leaving the Surface of the drop whence it flew very pretti- ly branched or creafed , which was eafily difeoverable by the Mierojoope, This drop,after I had thus ground it, without at all impairing the remnant that was not ground away, I caufed to fly immediately all into fand upon the nipping off the very tip of its flender end. Another of thefe drops I began to grind away at the fmaller end', but had not worn away on theftone above a quarter of an inch before the whole drop flew with a brisk crack into fand or fmall duff 5 nor woul4 it have held fb 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 tery tuff skin of lethyocoUa^ which being very tough and Very tfanfparent,was the mofl: convenient fubftance for thefe tryals that I could imagine, having dipt, I fay, feveral of thefe drops in this tranfparent Glue whilft hot, and fuffering them to hang by a firing tied about the end of them till they werecold, and the skin pretty tough 5 then wrapping all the body of the G , drop ^ 34 Micrographia. drop C leaving out only the very tip J in fine (upple Kids-leather very clofclyj nipped off the fmall top, and found, as I expeded, 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 impuHe; but yet the skin and leather was fo ftrong as to keep the parts from flying out of their former pofture 5 and, the skin being tranfparent , I found that the drop retained exadly its former fi- gure and polifli, but was grown perfedly 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* fcope^ 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 caled over with lUhyocoUa or lji»glafs ( by being ordered as is before pre- ‘ feribed ) crazed or flawed into pieces, but by the skin or cafe kept in its former figure , and each of its flawed parts preferved exadly in its due pofture 5 the outward appearance of it Ibmewhat plainly to the naked eye, but much more confpicuous if viewed with a fmall fenfs appeared imich after this fhape. That is , the blunt end B for a pretty breadth, namely , as far as the Ring C C C feemed irregularly flawed with divers clefts, which all ftemed to tend towards the Center of it, being, as I af- terwards found , and (ball anon ihew in the deftription 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 C to A was flawed with an infinite number of fmall and parallel Rings, which as they were for the moft part very round , fo were they very thick and clofo together, but were not fo exaftly flaw’d as to make a perfect Ring , but each circular part was by irregular cracks flawed like wife into multitudes of irregular flakes or tiles 5 and this order was obforved likewife the whole length of the neck. Now though I could not fo exadtly cut this conical Body through, the Axis^ as is reprefonted by the figure Y 5 yet by anatomizing^ as it were, offoveral, 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 fliouldwith a Microfeopeh-Avt^ouud 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- liical body of the Bafis C C is terminated, but as many of the parts of the drop as reach as high as DD. And it foemed to be the head or beginning of a Pith, as it v/ere, or a apart of the body which foemed more fpungy then the reft, and much more irregularly flawed, which from T afeended by E E, though lefs vi- fible, into the ihiall neck towards A. The Grain, as it were, of all the flaws, that from all the outward Surface A DC CD A, was much the fame,as is reprefonted by the black ftrokes that meet in the middle D T, DT, DE,DE, &c. Nor MlCROGRAPHIAi Nor is this kind of Grain , as I may call it, peculiar to Glals drops thus quenched 5 for (” not to mention Coperas-jiones ^ 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 obferved the lame in all manner of caft Iron , efpecially the coar- ftr Ibrt^ fuchas Steves, and Furnaces, and Backs, and Pots are made of.- For upon the breaking of any of thofe Subftances it is ob\aous to ob- ferve, how from theout-fides towards the middle, there is a kind of Radiation or Grain much relembling this of the Glals-drop^ but this -Grain is moft conlpicuous in Iron-bullets , if they be broken ; the fame ?h<£nomena may be produced by calling regulns of Antimony into a Bullet- mold, as alfo WithGlafs of Antimony^ or with almoft any luch kind of Vitrified Jubfiance , either caft into a cold Mold or poured into Water. Others of theft Drops I heat red hot in the fire, and then fuflered them to cool by degreeSi And theft I found to have quite loft all tYicirfulmi^ or flying quality, as allb their hard, brittle and Ipringy 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- cd, and it ftemed much of the fame confiftence with other green Glaft well nealed in the Oven. The Figure and bignels of theft for the moft part was the lame with that of the Figure Z ^ that is,all the furface of them was very finooth and polilht,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 flattedi. About D, which is at the upper part of the drop under that fide of the ftem which is concave , there ufually was made fomeoneor more little Hillocks or Prominences. The drop it ftlf, before it be broken, appears very tranlparent, and towards the middle of it, to be very full of fmall Bubbles, of Ibme kind of aerial fubftance, which by the refraction of the outward lurface appear much bigger then really they are, and this may be in good part removed, by putting the drop under the lurface 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 finaller* And this, by the by, minds me of the appearing magnitude of t\\G aper- ture o£ tixtiris^ox pupil oixh^ eye, which though it appear, and be there- fore judged very large , is yet not above a quarter of the bignels it ap- pears of^ by the lenticular refraCHon of the Cornea. The cauft of all which Vh<£nomena I imagine to be no other then this. That the Parts of the Glals being by the exceflive heat of the fire kept off and ftparated one from another, and thereby put into a kind of Hug- gift] fluid confiftence , are ftflered to drop oft with that heat or agitation remaining in them, into cold Water 5 by which means the outfides of the drop arc prefently cool’d and crufied , and are thereby made of a looft texture,becauft the parts of it have not time to fettle themftlves leifurely together , and lb to lie very cloft together : And the innermoft parts of the drop, retaining ftill much of their former heat and agitations, remain G 2 of Micrographia. of a loofe texture alfojand^^according as the cold ftrikes inwards from the bottom and (ides, are quenched, as it were, and made rigid in that very pofture wherein the cold finds them. For the parts of thecruji being already hardened , will not fuffer the parts to fhrink any more from the outward Surface inward 5 and though it fhrink a little by reafon of the fmall parcels of feme Aerial fubftances difperfed through the matter of the Glafs, yet that is not neer fo much as it appears f as I juft now hint- ed O nor if it were, would it be fufheient for to confblidate and condenfe the body of Glafs into a tuff and dole texture , after it had been lb ex^ ceflively ratified by the heat of the glals-Furnace. But that there may be Inch an expanfion of the aerial fubftance con- tained in thofc little blebbs or bubbles in the body of the drop, this fob lowing Experiment will make more evident. Take a fmall Glals-Canc about a foot long , feal up one end of it «fet/V^/^,then put in a very fmall bubble of Glals, almoftof theftiape of an Eflence-viol with the open mouth towards the lealed 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 ratified and driven out , then by fucking at the fmalling Pipe, more of the Air or vapours in the bubble may be luck’d out , lb 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 flender Pipe and let it cool : whereupon it is obvious to oblerve, firft, that the Water by degrees will llibfide and fhrink into much lels room : Next, that the Air or vapours in the Glals will expand themfelves lb, as to buoy up the little Glals : Thirdly, that all about the infide of the 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- lelves up and break at the top. From thisDifiediug of the heat in Glals drops, that is, by the quenching or cooling Irradiations propagated from the Surface upwards and in- wards, by the lines CT, CT, DT, DE,C^c. the bubbles in the drop have room to expand themfelves a little, and the parts of the Glals con- tradt themfelves 5 but this operation being too quick for the lluggilh parts of the Glafs, the contraftion is performed very unequally and irregularly, and thereby the Particles of the Glals are bent, Ibme one way, and Ibme another, yet lb as that moft of them draw towards the Pith or middle TEEE, or rather from that outward : fo that they cannot extricate on unbend themfelves, till fome part of T E E E be broken and loofened, for all the parts about that are placed in the nianner of an Arch , and lb till their hold at T EE E be loofened they cannot fly afunder, but up- hold, and Ihelter, and fix each other much like the ftones in a Vault, where each ftone does concurre to the ftability of the whole Fabrick, and no one ftone can be taken away but the whole Arch falls. And where- Ibever any of thofe radiating wedges DT D,€^c. are removed, which are the component parts of this Arch,the whole Fabrick prefently falls to pieces t M 1 C ROG R A P HlA. pieces^ for all the Springs of the feveral parts are fet at liberty, ^which immediately extricate themfelves and tly afunder every way ^ each part by its fpring contributing to the darting of it lelf and fome other contigu- ous part. But if this drop be heat lb hot as that the parts by degi'ces cart unbend themfelves, and be fettled and annealed in that pofture , and be then luffered gently to iubfide and cool ^ The parts by this nealing lo- fing their fpringinels , conftitute a drop of a more foft but iefs br ittle tex- ture,and the parts being not at all under a flexure, though any part of the middle or Pith T E E E be broken,ye$jWill not the drop at all fly to pieces as beforCi ’ . This Conjedure of mine I fliall indeavour to make out by explain- ing each particular Allertion with analogous Experiments ; The Aflertion« are thcfe. Firft , That the parts of the Clafs , whilfl: in a fluid Confiftence and hot , are more ratified , or take up more room , then when hard and cold. Secondly 5 That the parts of the drop do fufler a twofold contra- dion. Thirdly , That the dropping or quenching the glowing metal in 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. Fifthlyj That the Fabrick of the drop, that is able to hinder the parts from extricating themfelves, is anahgus to that of an Arch. Sixthly, That the hidden flying aliinder of the parts proceeds fioirt their fpringinels. Seventhly, That a gradual heating and cooling does anneal or reduce the parts of Glafs to a texture that is more loofe, andealilicr to be bro- ken, but not lb brittle. That the firft of thefe is true may be gathered from this, That Heat is a property of a body arftng from the motion or agitation of its parts 5 and therefore whatever body is thereby toucht muft neceflarily receive Ibmc part of that motion,whereby its parts will be lhaken and agitated, and lb by degrees free and extricate themfelves from, one another , and each part fo moved does by that tnotion exert a conatns of protruding and diP placing all the adjacent Particles,! Thus Air included in a veliel, 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 noile , thatitalmoft made me deaf for the prefent,and much lurpalled the noife of a Musket; The like have I done by throwinginto the fire fmall glals Bubbles her- metically lealed , With a little drop of Water included in them. Thus Water alfo,orany other Liquor ,included in a convenient veftel,b}" being wanned , manifeftly expands it felf with a very great violence , lb as to break the ftrongeft vefid, if when heated it be narrowly itnprilbned in it. This MlCROGRAPHiA. This is very manifeft by the feakdThermometers^ which I have, by feve^ ral tryals, at laft brought to a great certainty and tenderneis : for I have made fome with ftems 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 ufo for them are very thick,ftraight,and even Pipes of Glals,with a very fmall perforation , and both the head and body I have made on purpole at the Glafs-houfe , of the lame metal whereof the Pipes are drawn ; thele I can eafily in the flame of a Lamp, urged with the blafl: of a pair of Bellows, feal and clofe together, fo as to remain very firm, clofe and even 5 by this means I joyn on the body firftjand then fill both it and a part of the ftem, proportionate to the length of the ftem and the warmth of the lealbn I fill it in^with the befi: rectified Spirit of Wine high* ly ting cl with the lovely colour of Cocheneel^ which I deepen the more by pouring Ibme drops of common Spirit of Vrine , which mull: not be too well redified , becaufe it will be apt to make the Liquor to curdle and fl:ick in the Imall perforation of the liem. This Liquor I have upon tryal found the mofi: tender of any fpirituous Liquor,and thole are much more fenfibly affeded with the variations of heat and cold then other more fiegmatick and ponderous Liquors, and as capable of receiving a deep tindure, and keeping it,as any Liquor whatfoeVer 5 and ( which makes it yet more acceptable ) is not fubjed 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 feal and joyn on the head of it. Then, for graduating the Item, I fix that for the beginning of my di- vifion 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 [o(] or nought^ I place according to the Degrees of Expandon^ or ContratUon of the Liquor in proportion to the bulk it had when it indur’d the newly mention’d freez- ing cold. And this may be very eafily and accurately enough done by this following way ^ Prepare a Cylindrical veflel of very thin plate Brals or Silver, A B C D of the figure Z 5 the Diameter A B of whole cavity let be about two inches, and the depth B C the lame ^ let each end be cover’d with a flat and fmooth plate of the lame fubftance, clolely Ibder’d on, and in the midft of the upper cover make a pretty large hole E F, about the bignefs of a fifth part of the Diameter of the other 5 into this faften very well with cement a ftraight and even Cylindrical pipe of Glals, 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, lb that G from E may be diftant juft two inches, or the lame height with that of the cavity of the greater Cylinder, then divide the length EG 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^ MiCROGRAPHlA. der. This veffel being thus prepared, the way of marking and gradu- ating the ‘ihermometers may be very eafily thus performed : Fill this Cylindrical veflel with the fame liquor wherewith the momeUrs are fill’d, then place both it and the ihermometer you are td gmdtute^ in water that is ready to be frozen, and bring the furface of the liquor in the Jhermometer to the firft marke or [o], then fo proportion the liquor in the Cylindrical veliel, that the furface of it may )uft be at the lower end of the fmall glafs-Cylinder ^ then very gently and gradu- ally warm the water in which both the and this Cylindrical veflel ftand, and as you perceive the ting’d liquor to rife in both ftems^ with the point of a Diamond give feveral marks on the ftem of the Ther- mometer at thofe places, which by comparing the expanfion in both Stems, are found to correfpondto the divifions of the cylindrical veflel;> and having by this means marked Ibme few of thefe divifions on the Stem 3 it will be very eafie by thefe to mark all the reft of the Stem, and accordingly to aflign to every divifion a propet charadter. A ihermometer , thus marked and prepared, will be the fitteft Inftru- ment to make a Standard of heat and cold that cah be imagined. For being fealed up, it is not at all lubjeft to variation or wafting, nor is it lia- ble to be changed by the Varying prefliire of the Air , 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 Contraftion with Cold, is not peculiar to Liquors only, but to all kind of (olid Bodies alfo, elpeci- 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 llip,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 fufiered to cool again, as loon as it is cold it will be as movable, and as eafie to be turned as before. This Quality is alfo very obforvable in Lead^ Tih^ Silver.^ Antimony^ Titch^RofinyBees-tpaxyButterymdi the like^ all which, if after they be melted you lufler gently to cool , you lhall find the parts of the upper Surface to liibfide and fall inwards , lofing that plumpnefs and fmoothnels it had whilftin fufion. The like I have alfo obferved in the cooling of Clajs of Antimony^ which does very neer approach the nature of Glals, But becaule thefe are all Examples taken from other materials then Glals,and atgue only, that poflibly there may be the like property alfo in Glals, not that really there is 5 we lhall by three or four Experiments in- deavour to manifeft that alfo. And the Firft is an Oblervation that is very obvious even in thefe very drops, to wit,that they are all of them terminated with an unequal or ir- regular Surface , elpecially about the fmaller part of the drop , and the whole length of the ftem 5 as about D, and from thence to A, the whole Surface , which would haVe been round if the drop had cool’d leilurely, is, by being quenched haftily,very irregularly flatted and pitted 5 which Micrograph! A. I fuppofe proceeds partly from the Waters unequally cooling and pref* fing the parts of the drop, and partly from the felt-contradcing or fubfi- ding quality of the fubftance of the Glafs: For the vehemency of the heat of the drop caufes luch hidden motions and bubbles in the cold Wa- ter,that fome parts of the Water bear more forcibly againft one part then againft another , and confequently do more fuddenly cool thofe parts to which they are contiguous. A Second Argument may be drawn from the Experiment of cutting Glafles with a hot Iron. For in that Experiment the top of the Iron heats, and thereby rarifies the parts of the Glafs that lie jull: before the crack , whence each of thole agitated parts indeavouring to expand its lelf and get elbow-room, thrufts off all the reft of the contiguous parts, and conlequently 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 Glals, 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 Chymijis ufually cut off the necks of Glals-bodies, by two kinds of Inftruments, either by a glowing hot round Iron-Ring, which juft incompafles the place that is to be cut, orelfo by a Sulphur'd Threed, which is often wound about the place where the feparation 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- forely and gradually heated very hot. Both which Th£fiomena leem ma- nifeftly to proceed from the expanjion and contraftion of the parts of the Glafs , which is alfo made more probable by this circumftance which I have obferved , that a piece of common windbw-glafs being heated in the middle very luddenly with a live Coal or hot Iron,does ufoally 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 5 Take a Glals-pipe, and fit into it a folid ftick of Glals, fo 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 Glals of a confiderable length, and fit it fo between the two ends or forews of a Lath, that it may but juft eafily turn,and that the very ends of it may be juft toucht and lufteined thereby ; then applying the flame of the Gandle to the middle of it, and heating it hot, you will prefontly find the Glals to ftick very faft on thofo 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, anden y ou will find it as eafie to be turned round as at the firft. From all which Experiments it is very evident , that all thofe Bodies, and particularly Glafs, fuflers an Expanfion by Heat, and that a very con- fiderable Ml CROGRAPHIA. fidferable 6ne,whilft they are in a ftate of Fufion. For I elfewhere mentionj hafignothinghut an eff'eU of a Very fir ong and qnh-k^.JiMiqng whereby the farts arenas it rverejoofe'mdfmm. eaeh oiher^aml confynentiy^ leaTJt an interjacent face or vacuity 3 it folloivSi that all thole fhaken Particle muft heceflarily take up much more rooiii then when they were atxeftjand iay tjuietiy upon each other; And this is further confirmed by ^Patic£ hc^Ii^ Alabfiief which will hlanifeftly rife a fi?tlh or eighth part highef in ihe Po^ whiidit is boylingj then it will remain at^ both before and aftbrit be boyjv ed.The reafon of which odd Vbandmeiiin ' ( to hint inhere only the way!) is this f that there is in the dirious pdWtier of Alabaher^andicthdr'aakiding Stories, a certain watery fubfiance^ Whii:^hhfo'fi^^nd inbldded \V-ith tht folid Particles, that till the heat be very Gonfiderable they will not% away'5 blit after the heat is increafed tO fuch a degree , they Weak out every Way- in vapours, and thereby lb fhake and loOfen the Ihiall eorpiifies of the Pow- der from each other, that they become perfectly of the ridture-gf a fluid bo^ dy, arid one may move a Itick to arid fro through itj and ftir it as bafily as Water, and the Vapours burfl: and break out in bubbles juft as in bbyling Watei,and the like 3 whereas^ both before thofe watery parts are flying away, and after they are quite gone 5 thatls, beforehand dfter it have doriO boyling,all thofe eflefts ceafe , and a ftick is ds diffieultly moved to arid fro in it as in land, or the like. Which Explication I could eafily prove^ had ! time 5 but this is not a fit place for it. ’ To proceed therefore,! fay,thatthe droppirig of this expahded Body in- to cold Water, does make the parts of the Gklfs fufler a double conttabriori : The firft is, of thole parts which are rieer the Surface of thC Dfbpi FOr Cold, aslfaid befOre,contra£cingBodics,friatisi^y the abatetneyH 'of the^agifating fd-- (culty the parts fallingneerer together thepdrts next ddjoyirig to the Wateir riiuft needs lofe much of their motion ^ drid impart it to the AmbieriC-Watet (which the Ebullition and commotion of it manifcfts) and thereby betOriie a Iblid and hard cruft, Whilft the inrietmoft parts remain yet fiitidiand Ex- panded 5 whence, as they grow cold alfoby degreeS,their parts ffliift ttecefla:- rily be left at liberty to be cOndenled, but becdUleof the hardnefe of the outward eruft,the contrayiiori cannot be admitted thdt way^but there being many very Imall, and before iricOillJlicliOtW bubbles in the fubftarice of the Glals,Upon the lubliding of the parts of the Glafs,the agil lubftarice contain^ ed in them has liberty of exparidihg if lelf a litflejdrid thereby thofe bubblel grow much bigger jwhich is the leeorid Coritf actibh. Arid both thefe are fcori^ firmed from the appearance of the Drop it felf : for as for the OutWard parts^ wc fce,firft,that it is irregular and flifririik, as it were,- which is Catifed by the yielding a little of the hardened Skin to a Corittafciori , after the vEry olit- moft Surface is fettled 5 arid asfof theiritEfnal parts, one may With oiies naked Eye perceive abundance Of vety cohlpiCiiOtfs bubbles, and with the ^ierofcope mmy moxQi The Conlideration of which Particulars will eafily fhake the Third Politic on probablcjthat is,that the parts of the dfOp Will be Of a very hard, though of a ratified Texture 5 for if the outward parts of the Drop, by reafori of its hard cruft, will indure very little Gontr adion, and the igil Particles,^ iticlti- H ded Micrographia. ded inthofe bubbles, by the lofing of their agitation, by thedecreafe of the Heat,lo(e alfo moft part of their Spring and Expanfive power^it follows (the withdrawing of the heat being very ludden) that the parts muft be left in a very loofe Texture, and by reaibn of the implication of the parts one about another,which from their lluggifrines and glutinoufnelslluppole to be much after the manner of the flicks in a Thorn-bufh,or a Lock of Woofrit will fol- low, I lay, that the parts will hold each other very ftrongly together,and in- dcavour to draw each other neerer together , and confcqucntJy their Tex- ture muft be very hard and ftifl, but very much ratified. And this will make probable my next Pofition, That the parts of the Glafi ure under a kind of tenjion or flexure^out of which they indeavour to extricate and free thetnje Ives ^znd thereby all the parts draw towards the Center or middle, and would, if the outward parts would give way, as they do when the out- ward parts cool leilurely (as in baking of ClaflesJ) contrad the bulk of the drop into a much Ids compafs. For fince.as I proved before,the Internal parts of the drop, when fluid, were of a very ratified 1 exture,and,as it were,tos’d open like a Lock of Wool, and if they were fuffered leifurely to cool, would be again preft, as it were, dole together; And lince that the heat, which kept them bended and open, is removed , and yet the parts not fufiered to get as neer together as they naturally would , It follows,that the Particles remain under a kind of tenfon and flexure , and conlequently have an indeavour to free themlelves from that bending and diflenjion^ which they do, as loon as either the tip be broken, or as foon as by a leifurely heating and cooling, the parts are nealed into another pofture. And this will make my next Pofition probable,that the parts of theGlafs drops are contignated together in the form of an Archymd cannot any where yield or be drawn inwards,till by the removing of Ibme one part of itfas it happens in the removing one of the ftones of an Arch)the whole Fabrick is (hatter d,ahd falls to picces,and each of the Springs is left at liberty ,fuddenly to extricate it felf: for fince I have made it probable,that the internal parts of the Glafs have a contradive power inwards, and the external parts are incapable of (uch a Contradion,and the figure of it being (pherical^it follows,that the fuperficial parts muft bear againft each other , and keep one another from being con- dens’d into a le(s room, in the (ame manner as the ftones of an Arch conduce to the upholding each other in that Figure. And this is made more probable by another Experiment which was communicated to me by an excellent Per- Ibn,who(e extraordinary Abilities in all kind of Knowledg, efpecially in that of Natural things,and his generous Dilpofition in communicating,incouraged me to have recourlc to him on many occafions. The Experiment was this ; Small Glals-balls ( about the bignefs of that reprelented in the Figure &.) would, upon rubbing or fcratching the inward Surface, fly all infiinder, with a pretty brisk noi(e 5 whereas neither before nor after the inner Surface had been thus (cratcht, did there appear any flaw or crack. And putting the pie- ces of oneofthofe broken ones together again, the flaws appeared much after the manner of the black lines on the Figure, Thele Balls were fmall, but exceeding thick bubbles of Glals , which being crack’d off from the Tuntilion whilft very hot , andfo fuffered to cool without nealing them in the Micrograph! A. the Oven over the Furnace , do thereby (f being made of white diafs, \v hich cools much quicker then green Clafs , and is thereby made much brittlerj acquire a very porous and very brittle texture: lb that if with the point of a Needle or Bodkin , the infide of any of them be rubbed prety hard, and then laid on a Table , it will, within a very little while, break into many pieces with a brisk noife , and throw the parts above a Ijpan afunder on the Table: Now though the pieces are not (b fmallas thofe of a fulminating drop, yet they as plainly Ihew, that the outward parts of the Glals have a great Conatus to fly afunder, were they not held together by the tenacity of the parts of the inward Surface : for we fee as fbon as thofe parts are crazed by hard rubbing, and thereby their tena- city fpoiled, the fpringinels of the more outward parts quickly makes a divulfion, and the broken pieces will, if the concave Surface of them be further fcratcht with a Diamond, fly again into fmaller pieces. From which preceding confiderations it will follow Sixthly , That the flidden flying afunder of the parts as fbon as this Arch is any where difbr- dcred or broken, proceeds from the fpringing of the parts , which ,indea- vouring to extricate themfelves as fbon as they get the liberty , they per- form it with fuch a quicknefs,that they throw one another away with very great violence .* for the Particles that compofe the Cruft have a Cohatus to lye further from one another,and therefore as foon as the external parts are locfened they dart themfelves outward with great violence, juft as fb many Springs would do, if they were detained and faftened to the body, as foon as they fhould be fuddcnly loofenedj and the internal parts draw- ing inward, they contraft fo violently, that they rebound back again and fly into multitude of fmall fhivers or fands. Now though they appear not, either to the naked Eye, or the Microfeope^ yet I am very apt to think there may be abundance of fmall flaws or cracks , which , by reafbn the ftrong refleding Air is not got between the contiguous parts, appear not* And that this may be fo , I argue from this , that I have very often been able to make a crack or flaw, in fbme convenient pieces of Glafs,to appear anddilappear atpleafure, according as by preffing together, or pulling aliinder the contiguous parts , I excluded or admitted the ftrong refled- ing Air between the parts : And it is very probable, that there may be ferae Body, that is either very ratified Air, or (ornerKinganalogoustoit, which fills the bubbles of thefe drops , which I argue, firft, from the round- nefs of them, and next, from the vivid refledtion of Light which they ex- hibite ; Now though I doubt not , but that the Air in them is very much rarified,yet that there is feme in them, to fuch as well eonfidcr this Expe- riment of the difappearing of a crack upon the extruding of the Air j I fuppofe it will feem more then probable. I’he Seventh and laft therefore that I fhall prove, is. That the gradual heating and cooling of thefe fo extended bodies does reduce the parts of the clafs to a loojer and fof ter temper. And this I found by heating them, and keeping them lor a prety while very red hot in a fire , for thereby I found them to grow a little lighter , and the fmall Stems to be very eafily bro- ken and Inapt any where , without at all making the drop fly j whereas H 2 before Micrographia. before they were fo exceeding hardjthat they could not be broken with» out much difficulty , and upon their breaking the whole drop would fly in pieces with very great violence. The Reafon of which laft leems to be 5 that the leifurely heating and cooling of the parts does not only waft fome part of the Glalsit felf , but ranges all the parts into abetter order, and gives each Particle an opportunity of relaxing its felf, and confequently neither will the parts hold fo ftrongly together as before, nor be fo difficult to be broken : The parts now more eafily yielding, nor will the other parts fly in pieces , becaufe the parts have no bended Springs. The relaxation alfo in the temper of hardned Steel , and ham- mered Metals.by nealing them in the fire,leems to proceed from much the fame caufe. F or both by quenching fuddenly fuch Metals as have vitri~ fed parts interfpers’d, as Steel has,and by hammering of other kinds that do not fo much abound with them, as Silver, Brafs, &c. the parts are put into and detained in a bended pofture , which by the agitation of Heat are ftiaken, and loofened, and (uffered to unbend themfclves. Obferv. VIII. Of the fiery Sparks ftruck from a Flint or Steel, ] T is a very common Experiment , by ftriking with a Flint againft a Steeljto make certain fiery and fhining Sparks to fly out from between thofe two comprefling Bodies. About eight years fince , upon cafoally reading the Explication of this odd Phenomenons by the moft Ingenious Des Cartes , I had a great defire to be latisfied , what that Subftance was that gave fuch a fhining and bright Light ; And to that end I fpread a fheet of white Paper,and on it, obferving the place where feveral of thefe Sparks fcemed to vanifh, I found certain very (mall, black, but gliftering Spots of a movable Subftance, each of which examining with my Mifero- cope^l found to be a fmall round Globule 5 fome of which, as they looked prety fmall, fo did they from their Surface yield a very bright and ftrong reflexion on that fide which was next the Light 5 and each look’d almoft like a prety bright Iron-Ball, whofe Surface was prety regular, fuch as is reprefented by the Figure A. In this I could perceive the Image of the Window prety well, or of a Stick, which I moved up and down between the Light and it. . Others I found,which were, as to the bulk of the Ball, prety regularly round, but the Surface of them,as it was not very foiooth, but rough,and more irregular, fo was the refleftion from it more faint and confufed. Such were the Surfaces of B. C. D. and E. Some of thefe I found cleft or cracked, asC, others quite broken in two and hollow, as D. which fcemed to be half the hollow fhell of a Granado, broken irre- gularly in pieces. Several others I found of other fhapes 3 but that which is reprefented by E, I obferved to be a very big Spark of Fire, which went out upon one fide of the Flint that I ftruck fire withal! , to which Micrographia. which it ftuckby the root F, at the end of which fmall Stem wasfeften- ed-on aHemJphere^ or half a hollow BalljWith the mouth of it open from the ftemwardsj fo that it looked much like a Funnel, or an old £a(hioned Bowl without a foot. This night, making many tryals and obfervations of this Experiment,! met, among a multitude of the Globular ones v/hich I had obferved, a couple of Inftances, which are very remarkable to the confirmation of my Hypothefis. And the Firft was of a pretty big Ball faftened on to the end of a linall (liver of Iron,which Compofitum feemed to be nothing elfe but a long thin chip of Iron, one of whofe ends was melted into a fmall round Glob^^the other end remaining unmelted and irregular, and perfectly Iron. The Second Inftance was not lefs remarkable then the Firft 5 for I found, when a Spark went out, nothing but a very fmall thin long fliver of Iron or Steel , unmelted at either end. So that it feems, that fome of thefe Sparks are the (livers or chips of the Iron vitrified , Others are on- ly the flivers melted into Balls without vitrification , And the third kind are only fmall flivers of the Iron, made red-hot with the violence of the ftroke given on the Steel by the Flint. He that (hall diligently examine the Phenomena of this Experiment, will, I doubt not, find caufe to belieVe, that the realbn I have heretofore given of it, is the true and genuine caufe of it, namely. That the Sparky appearing Jo bright in the fallingys nothing elfe but a jmali piece of the Steel or Flint-^ but mofi commonly of the Steely which by the violence of the firok§ if at the fame time fever d and heatt red-hot , and that fometimes to fitch d degree ^ as to makg it melt together into a fmall Globule of Steel 5 and fome- times alfo is that heat fo very intenfe^ as further to melt it and vitrifie it 5 but many times the heat is fo gentle^ as to be able to make the fliver only redhoty which notwithfianding falling upon the tinder ( that is only a very curious (mail Coal made of the fmall threads of Linnen burnt to coals and chafdj it eafily fits it on fire. Nor will any part of this Hypothefis feem ftrange to him that confiders, Firft, that either hammering, or filing, or otherwife violently rubbing of Steel, will prefently make it fo hot as to be able to burn ones fingers. Next , that the whole force of the ftroke is exerted upon that (mail part where the Flint and Steel firft touch : For the Bodies being each of them fo very hard , the puls cannot be far com- municated, that is, the parts of each can yield but very little, and there- fore the violence of the concuflion will be exerted on that piece of Steel which is cut off by the Flint. Thirdly , that the filings or fmall parts of Steel are very apt, as it were,to take fire, and are prefently red hot, that isjthere feems to be a very combufiible fulphnreous Body in Iron or Steel, which the Air Very readily preys upon, as foon as the body is a little vio- lently heated. And this is obvious in the filings of Steel or Iron caft through the flame of a Candle 3 for even by that fudden of the fmall chips of Iron, they are heat red hot, and that combufiible Julphureous Body is prefent- ly prey’d upon and devoured by the incompafling Meifiruum, whofe office in this Particular I have (hewn in the Explication of Char- cole. And 4^ M I C R O G R A P H I A . And in profecution of this Experiment^having taken the filings of Iron and Steel, and with the point of a Knife call: them through the flame of a Candle , I obferved where Ibrae confpicuous Ihining Particles fell , and looking on them with my Microfiope , I found them to be nothing elfe but fuch round Globules, as I formerly found the Sparks ftruck from the Steel bv a ftroke to be, only a little bigger ^ and (baking together all the filings that had fallen upon the (heet of Paper underneath, and obferving them with the Mkrofcope. I found a great number of (mall Globules, (uch as the former, though there were alio many of the parts that had remain- ed untoucht, and rough filings or chips of Iron. So that, it Teems, Iron does contain a very combufiible fidphnreous Body, which is, in all likeli- hood, one of the caufes of this Vh^nomenon , and which may be perhaps very much concerned in the bufinels of its hardening and tempering ; of which fomewhat is Tiid in the Delcription of Mujiovy-gUfs. So that, thefe things confidered, we need not trouble our (elves to find out what kind of Pores they are, both in the Flint and Steel, that contain the Atoms of fire , nor how thofe Atoms come to be hindred from run- ning all out , when a dore or paflage in their Pores is made by the con- cuflion ; nor need we trouble our felves to examine by what Vrometheus the Element of Fire comes to be fetcht down from above the Regions of the Air, in what Cells or Boxes it is kept, and what Epimethens lets it go : Nor toconfider what it is that caufes (b great a conflux of the atomical Particles of Fire, which are faid to fly to a flaming Body, like Vultures or Eagles to a putrifying Carcals, and thereto make a very great pudder. Since we have nothing more difficult in this Hypothejis to conceive, fir(t, as to the kindling of Tinder, then how a large Iron-bullet, let fall red or glowing hot upon a heap of Small-coal, (houldfet fire to thole that are next to it firfl: ; Nor fecondly, is this lafi: more difficult to be explicated, then that a Body, as Silver for Inftance, put into a weak Menjiruum^ as Aqua fortis (hould , when it is put in a great heat , be there diflblved by it, and not before 5 which Hypothefis is more largely explica- ted in the Delcription of Charcoal. To conclude, we (ee by this In- ftance, how much Experiments may conduce to the regulating of Philo- fophical notions. For if the moft Acute Des Carteshzd applied himfelf experimentally to have examined what fubftance it was that caufed that Ihining of the falling Sparks ftruck from a Flint and a Steel , he would certainly have a little altered his , and we (hould have found, that his Ingenious Principles would have admitted a very plaufible Ex- plicadon of this Phenomenon , whereas by not examining (b far as he might , he has fet down an Explication which Experiment do’s contra- did. But before I leave this Defcription, I muft not forget to take notice of the Globular form into which each of thele is moll curioudy formed. And ^s Phenomenon^ as I have ellewhere more largely (hewn, proceeds from a' propriety which belongs to all kinds of fluid Bodies more or le(s,and is caufed by the Incongruity of the Ambient and included Fluid, which lb afts and modulates each other , that they acquire , as neer as is poflible. Micrograph! A. pofliblc^ja fperical ov globular iovm^ which proprifety and (everal of the ?h£itomena that proceed from it, 1 have more fully explicated in the fixth Oblervation. One Experiment, which does very much illuftrate my pre/ent Explica- tion, and is in it felf exceeding pretty, I muft not pafs by : And that is a way of making fmall ov Balls of Lead, or Tin, as finall alraoft as thefe of IrOn or Steel, and that exceeding eafily and quickly, by turning the filings or chips of thole Metals allb into perfectly round Globules^ The wayj in lhort,as I received it from the Learned Thyjitian Do&or I. G. is this 5 Reduce the Metal yOu would thuslhape, into exceeding fine filings, the finer the filings are, the finer will the Balls be: Stratifie^e.(c filings with the fine and well dryed powder of quick Lime in a Crucible propor- tioned to the quantity you intend to make ; When you have thus filled your Crucible^ by continual firatifications of the filings and powder, fb that.as neerasmay be, no one of the filings may touch another, place the Crucible in a gradual jire , and by degrees let it be brought to a heat big enough to make all the filings, that are mixt with the quick Lime, to melt, and no more 3 for if the fire be too hot , many of thefe filings will joyn and run together 3 whereas if the heat be proportioned j upon walhing the Lime-duft in fair Water , all thofe fmall filings of the Metal will lub- fide to the bottom in a moft curious powder , confiding all of exactly round Globules^ which, if it be very fine, is very excellent to make Hour- glaflb of. Now though quick Lime be the powder that this direftion makes choice of, yet I doubt not, but that there may be much more convenient ones found out, one of which I have made tryal of, and found very effe- ftual 3 and were it not for difeovering, by the mentioning of it, another Secret ^ which I am not free to impart , I Ihould have here inferred it. Obferv. IX. Of the Colours obfervahle in Mufeovy Glafs^ and other thin Bodies. M 01 covy“glals,or La^is Jpecularif^jis a Body that (eems to have as ma- ny Guriofities in its Fabrick as any common Mineral I have met with : for firft , It is tranfparent to a great thicknefs : Next, it is com- pounded of an infinite number of thin flakes joyned or generated one upon another fo elofe & fmooth,as with many hundreds of them to make one Imooth and thin Plate of a tranlparent flexible fiibftance,which with care and diligence may be flit into pieces fo exceedingly thin as to be hardly perceivable by the eye, and yet even thofo, which I have thought the thinned, I have with a good Microjeope found to be made up of many ether Plates, yet thinner 3 and it is probable, that. Were our much Ml CROGRAP HIA. much better , we might mueh further difcover its divifibility. Nor are thefc flakes only regular as to the fmoothnels of their Surfaces , but third- ly 5 In many Plates they may be perceived to be terminated naturally with edges of the figure of a Rhomhodd. This Figure is much more con- Ipkuous in our Englifli talk, much whereof is found in the Lead Mine's, and is commonly called spar , and Kauck^ ^ which is of the lame kind of liibftance with but is feldom found in fo large flakes as thafe is, nor is it altogether lb tulfj but is much more clear and tranfoarent,and mueh more curioufly lhaped , and yet may be cleft and flak’d like the o- ther Seknitk, But fourthly, this ftone has a property, which in refpeft of the Jlltcrofcope^ is more notable, and that is, that it exhibits feveral ap- pearances of Golours5 both to the naked Eye, but much more conlpicu- oully to the Mierdfeope ^ for the exhibiting of which , I took a piece of Mufcovy-glafi^ and Iplitting or cleaving it into thin Plates, I found that up . and down in leveral parts of them I could plainly perceive feveral white Ipccks or flaws, and others diverOy coloured with all the Colours of the Rainbow 5 and with the Microjiope I could perceive , that thefe Colours were ranged in rings that incompaffed the white Ipeck or flaw, and were round or irregular, according to the lhape of the fpot Which they termi- nated 5 and the pofition of Colours, in rel|3ed: of one another, was the very lame as in the Rainbow, The conlecution of thofe Colours from the middle of the Ipot outward being Blew, Purple, Scarlet, Yellow, Greeny Blew, Purple, Scarlet, and fo onwards, fometimes half a foore times re- peated,that is,thcre appeared hx,foven,eight,nine or ten feveral coloured rings or lines, each incircling the other, in the lame manner as I have of- ten foen a very vivid Rainbow to have four or five feveral Rings of Co- lours, that is, accounting all the Gradations between Red and Blew for one : But the order of the Colours in thefe Rings was quite contrary to the primary or innermoft Rainbow ^ and the fame with thofo of the focon- dary or outermoft Rainbow , thefe coloured Lines or Irifes^ as I may fo call them , were fome of them much brighter then others , and fome of them alfo very much broader, they being fome of them ten, twenty, nay, I believe , neer a hundred times broader then others 5 and thofe ufoally were broadifh which were neereft the center or middle of the BaW. And oftentimes I found , that thefe Colours reacht to the very middle of the flaw , and then there appeared in the middfe a very large fpot , for the moft part, all of one colour , which was very vivid , and all the other Colours incompaffing it, gradually afeending, and growing narrower to- wards the edges, keeping the fame order , as in the jeenndafy Rainbow, that is,if the middle were Blew, the next incompaffing it would be a Pur- ple,the third a Red, the fourth a Yellow, &c, as above if the middle were a Red,the next without it would be a YelloW,the third a Green, the fourth a Blew,and fo onward,. And this order it alwayes kept whatfo- ever were the middle Colour. There was further obfervable in feveral other parts of this Body, ma~ ny Lines or Threads,each of them of fome one peculiar Colour, and thofe fo exceedingly bright and vivid , that it afforded a very picafantobjed through MlCROGRAPHIAi through the Microfcope. Sortie of thefe threads I have oBferved al/b to be pieced or made up of feveral fliort lengths of differently coloured ends (' as I may fb call them ) as a line appearing about two inches long through the Microfeope , has been compounded of about half an inch of a Peach colour, w of a lovely Grafs-green, f of ah inch more of a bright Scarletjand the reft of the line of a Watchet blew. Others of them were much otherwife coloured 5 the variety being almoft infinite. Another dung which is very obfervablej is, that if you find any place where the colours are very broad and confpicuous to the naked eye, you may, by prefling that place with your finger, make the colours change places,and go from one part to another. 'There hone rhanomenon more, which may, if care be ufed^ exhi- bit to the beholder, as it has divers times to me, an exceeding pleafant, and toot lefsinftrudlive Spedacle 5 And that is, if curiofity and diligence beufed , you may fo fplit this admirable Subftance , that you may have pretty large Plates ( in comparifon of thofe fmallefones which you may obferve in the Rings ) that are perhaps an i or a ^ part of an inch over^ each of them appearing through the Mkrofeope moft curioully, intirely^ and uniformly adorned with fome one vivid colour ; this, if examined Vfiththe Mkrofeope , maybe plainly perceived to be in all parts of it e- qually thick. Two, three, or more of thefe lying one upon another, ex- hibit oftentimes curious compounded colours , which produce fuch a Cofnpi^tHm 3 as One would ftarce imagine fhould be the refult of fuch in- gredients : As perhaps a faint yellovo and a blew may produce a very deep pnrple. But when anon we come to the more ftrid examination of thefe Fbanomena^ and to inquire into the caufes and reafons of thefe produfti- cnsjWe fhall,! hope , make it more conceivable how they are produced,; and fhewthemtobc no other then the natural and neceftary effeds ari- lingfrom the peculiar union of concurrent caufes. Thefe rheenomena being fb various, and fb truly admirable, it will cer- tainly be very well worth our inquiry , to examine the caufes and reafbns of them,and to confider, whether from thde caufes demonftratively evi- denced , may not be deduced the true caufes of the produdion of all kind of Colours. And I the rather now do it , inftead of an Appen- dix or Digreflion to this Hiftory, then upon the occafion of examining the Colours in Peacocks, or other Feathers, becaufe this Sub jed , as it docs afibrd more variety of particular Colours , fb does it affbrd much better wayes of examining each circumftance. And this will be made manifeft to him that confiders , firft , that this laminated body is more Ample and regular then the parts of Peacocks feathers, this confifting on- ly of an indefinite number of plain and fmooth Plates, heaped up, or in- cumbent on each other; Next, that the parts Of this body are rriuch more manageable, to be divided or joyned, then the parts of a Peacocks fea- ther,or any other ftibftance that I know. And thirdly, becaufe that in this; we arc able from a colourlefs body to produce feveral coloured bodies, affording all the variety of Colours imaginable : And feveral others, which the fubfequent Inquir}" will make manifeft. I To Micrographia. To begin therefore^ it is manifeft from Icveral circumftances, that the material caufe of the apparition of thefe feveral Colours , is fome Lamina. or Plate of a tranfparent or pellucid body of a thickncfi very determi- nate and proportioned according to the greater or lefs refradivc power of the pellucid body. And that this is fo.abundance of Inftances and par- ticular Circumftances will make manifeft. As firfl 3 if you take any fmall piece of the Mufcovy-glafs , and with a Needle , or fome other convenient Inftrument, cleave it oftentimes into thinner and thinner Lamina^ you fhall find, that till you come to a deter- minate thinnefs of them, they fhall all appear tranfparent and colourlefs, but if you continue to I'plit and divide them further, you fhall find at lafV, that each Plate, after it comes to flich a determinate thicknefs, fhall ap- pear moft lovely ting’d or imbued with a determinate colour. further, by any means you fo flaw a pretty thick piece, that one part does begin to cleave a little from the other, and between thofe two there be by any means gotten fome pellucid medium, thole laminated pellucid bodies that fill that fpace, fhall exhibit feveral Rainbows or coloured Lines, the co- lours of which will be difpofed and ranged according to the various thicknefles of the feveral parts of that Plate. That this is fo, is yet fur- ther confirmed by this Experiment. Take two fmall pieces of ground and polifht Looking-glafs-plate, each about the bignefs of a fhilling, take thefe two dry , and with your fore-fingers and thumbs prefs them very hard and clofe together,and you fhall find; that when they approach each other very near, there will ap- pear feveral Irijes or coloured Lines, in the fame manner almoft as in the Mufcovy-glafs and you may very eafily change any of the Colours of any part of the interpofed body, by preffing the Plates clofer and hard- er together,or leaving them more lax that is, a part which appeared co- loured with a red, may be prefently ting’d with a yellow, blew, green, purple , or the like , by altering the appropinquation of the terminating Plates.Now that air is not neceflary to be the interpofed body, but that any other tranfparent fluid will do much the fame, may be tryed by wet- ting thofe approximated Surfaces with Water , or any other tranfparent Liquor, and proceeding with it in the fame manner as you did with the Air ^ and you will find much the like effed: , only with this difference, that thofe compreff: bodies, which differ moft, in their refraftivc quality, from the compreffing bodies , exhibit the moft ftrong and vivid tin- ftures. Nor is it neceflary , that this laminated and tingd body fbould be of a fluid fubftance , any other fubftance , provided it be thin enough and tranfparent, doing the fame thing : this the Lamina oi our Mufeovy- glafs hint 5 but it may be confirm’d by multitudes of other Inftances. Andfirft, we fhall find, that even Glafs it felf may, by the help of a Lamp, be blown thin enough to produce thefe Phenomena of Co- lours : which Phanomena accidentally happening , as I have been attempting to frame fmall Glafles with a Lamp , did not a little furprize me at firft , having never heard or feen any thing of it before 5 though afterwards comparing it with the Phanemena , I had often obferved ]\4iCR0GRAi*HiA. obferved in thofe Bubbles which Children ufe to make with Soap-waiter, I did the lels wonder 5 efpecially when upon Experiment I found, I Was able to produce the fame Fhanoixeiia in thin Bubbles rhade with any other tranfparent Subftance. Thus have I produced t hem with Bubbles of Vitch.^ U:o^n^Colophony^T7irpent7Ke^ Sohftivns Arabick^ in watery any glutinvm Liquor,as Wurt^WineySpirit of Wme^ Oyl of Turpentine^ Glare of Snails^ 8cc. It would needlefs to enumerate the feveral Inftances thefo being enough to (hew the generality or univerlality of this propriety. Only I muft not omit, that we have inftancesalfo of this kind even in metalline Bodies and animal 5 for thole feveral Colours which are oblerved to fol- low each other upon the polilht liirface of hardned Steel, when it is by a fuflicient degree of heat gradually tempered or foftened , are produced from nothing elfe but a certain thin Lamina of a t^itrum or vitrifkd part of the Metal, which by that degree of heat, and the concurring aftkm of the ambient Air,is driven out and fixed on the fUrfaceof the Steel. And this hints to me a very probable ( at leaft, if not the true) caule of the hardning and tempering of Steel, which has not, I think, been yet gi ven,nor, that I know of,been lb much as thought of by any. And that is this, that the hardnels of it arifes trom a greater proportion of a vitrifi-^ ed Subftance interfperled through the pores of the Steel. And that the tempering or Ibftning of it arifes frt)m the proportionate or (mailer parcels of it left within thofe pores. This will feem the more probable , if we conlider thefe Particulars. Firft, That the pure parts of Metals are of themfelves very flexible and tujfy that is, will indure bending and hammering, and yet retain their continuity. Next, That the Parts of all vitrified Subftances, as all kinds of Glals, the Scoria of Metals, <&c. are very hard, and allb very brittle, being neb ther flexible nor malleable ^ but may by hammering or beating be broken into fmall parts or powders. Thirdly ,That all Metals ( excepting Gold and Silver , which do not lb much with the bare fire, unlels affifted by other feline Bodies ) do more or left vitrifie by the ftrength of fire, that is, are corroded by a fe- line Subftance, which I elfewhere (hew to be the true caufe of fire 5 and are thereby, as by feveral other Menjiruums^comerted into Scoria 5 And this is called, calcining o£thsm^ by Chimifts. Thus Iron and Copper by heating and quenching do turn all of them by degrees into Scoria^ which are evidently Subftances , and unite with Gla(s , andareeafily fufible 5 and when cold, very hard, and very brittle. Fourthly, Thatmoft kind of Vitrifications or Calcinations ^Lvcm^dthy Salts, uniting and incorporating with the metalline Particles. Nor do I know any one calcination wherein a Saline body may not, with very great probability, be feid to be an agent or coadjutor. Fifthly, That Iron is converted into Steel by means of the incorpofa- tion of certain falts, with which it is kept a eertain time in the fire. 52 Mi CROGRAP HIA. Sixthly, That any Iron may, in a very little time, be cafe hardned^ as the Trades-men call it, by cafing the iron to be hardned with clay, and putting between the clay and iron a good quantity of a mixture otVrwCy Soot^Sea-Jalty Sind Horfes hoofs (all which contein great quantities of Sa- line bodies) and then putting the cafe into a good ftrong fire, and keep- ing it in a confiderable degree of heat for a good while, and afterwards heating, and quenching or cooling it fuddenly in cold water. Seventhly ,That all kind of vitrify ’d fubftancesjby being fuddenly cool’d, become very hard and brittle. And thence arifes the pretty Pheenomena of the Glafs Drops, which I have already further explained in its own place. Eighthly, That thofe metals which are not fb apt to vitrifie, do not ac- quire any hardnefs by quenching in water, as Silver, Gold, Sec. Thcfe confiderations premis’d, will, I fuppofe, make way for the more eafie reception of this following Explication of the Ph