most to replenish the Receiver they did not sensibly hinder the Air included in the Bladder from dilating it self after the same manner for ought we could discern as it would have otherwise done So that before the Fire or the Match was quite extinct the Bladder appear'd swell'd at least to six or seven times its former capacity Since the writing of these last Lines we took a small Receiver capable of containing by guess about a pound and a half of Water and in the midst of it we suspended a lighted Match but though within one minute of an hour or thereabouts from the putting in of the Match we had cemented on the Cover yet we could not make such haste but that before we began to pump the Smoke had so fill'd that small Receiver as for ought we discern'd to choke the Fire And having again and again reiterated the Experiment it seem'd still as at first that we could not close up the Vessel and pump out all the Fumes time enough to rescue the Fire from Extinction whereupon we made use of this Expedient Assoon as we had pump'd once or twice we suddenly turn'd the Key and thereby gave access to the excluded Air which rushing violently in as if it had been forced thorow a pair of Bellows did both drive away the ashes fill the Glass with fresh Air and by blowing the almost extinguish'd Fire re-kindl'd it as appear'd by the Matches beginning again to smoke which before it had ceas'd to do we having by this means obtain'd a lighted Match in the Receiver without being reduc'd to spend time to close it up commanded the Air to be immediatly pump'd out and found that upon the exsuction of it the Match quickly left smokeing as it seem'd by reason of the absence of the Air and yet if some urgent occasions had not hinder'd us we would for greater security have try'd whether or no the Match rekindled as formerly would smoke much longer in case of no exsuction of the ambient Air. Experiment 14. TO try diverse things at once and particularly whether Fire though we found it would not long last might not yet be produced in our evacuated Receiver We took a Pistol of about a Foot in length and having firmly tyed it to a stick almost as long as the Cavity of the Receiver we very carefully prim'd it with well dry'd Gun-powder and then cocking it we ty'd to the Tricker one end of a string whose other end was fasten'd to the Key formerly mention'd to belong to the Cover of our Receiver This done we convey'd the Pistol together with the annexed Staff into the Vessel which being clos'd up and empty'd after the usual manner we began to turn the Key in the Cover and thereby shortning the string that reach'd from it to the Pistol we pull'd aside the Tricker and observ'd that according to our expectation the force of the Spring of the Lock was not sensibly abated by the absence of the Air. from whose impetus yet some Modern Naturalists would derive the cause of the motion of Restitution in solid Bodies For the Cock falling with its wonted violence upon the Steel struck out of it as many and as conspicuous parts of Fire as for ought we could perceive it would have done in the open Air. Repeating this Experiment divers times we also observed whether or no there would appear any considerable Diversity in the Motion of the shining Sparks in a place where the remaining Aire was so much rarified but could not perceive but that they moved some of them upwards as well as some of them downwards and some of them side-ways as they are wont to do when upon such collisions they fly out in the open Air. We likewise caus'd a piece of Steel to be made of the form and bigness of the Flint in whose place we put it and then the Pistol being cock'd and conveyed into the Receiver the Trigger was pull'd after the Air was drawn out And though the place were purposely somewhat darken'd yet there appear'd not upon the striking of the two Steels against each other the least spark of Fire Nor did we expect any having before in vain attempted to strike Fire this way in the open Air though we thought fit to make the Experiment to undeceive those who fancy in rarified Air I know not what strange disposition to take Fire upon a much slighter occasion then this Experiment afforded We have indeed found that by the dextrous Collision of two harden'd pieces of Steel store of sparks may be struck out But that was done with such vehement percussion of the edges of the two Steels as could not well be compass'd in our Receiver But the chief thing we design'd to do with our Pistol was To observe whether Gun-powder would take Fire in our empty'd and closely stop'd Glass Whether the expansion of the Flame would be considerably varied by the absence of so much of the ambient Air as was drawn out of the Receiver and whether the Flame would diffuse it self upward as it is wont notwithstanding it s not having about it the usual proportion of Air to force it up And though most of our attempts to fire the Gun-powder in the Pan of the Pistol succeeded not because we were fain to let it hang almost perpendicular in the Receiver whereby the Powder was shaken down before the sparks could reach it yet once the Experiment succeeded and the kindled Powder seem'd to make a more expanded Flame then it would have done in the open Air but mounted upwards according to its wont whether by reason of that little portion of Air which in spight of our pumping remained in the Receiver or for any other cause we have not now the leisure to consider But we must not forget that upon the extinction of the Flame the Receiver appear'd darken'd with smoke which seem'd to move freely up and down and upon the letting in the Air at the Stop-cock began to circulate much faster then before We would have made more observations concerning this Flame but that of two or three attempts we afterwards made to repeat the kindling of Powder not any one succeeded and we have not the leasure to dwell long upon one kinde of Tryals Experiment 15. TO these Experiments concerning Fire we added another which though it succeded not may perhaps without impertinency be recorded partly because that as we have in another Treatise amply declar'd it is usefull to recite what Experiments miscarry as well as what succeed And partly also because it is very possible that what we endeavored in vaine may be performed by Your Lordship or some other Virtuoso that shall have slancker Vessells then we had and more Sunny dayes then the present Winter allows us We convey'd then into one of our small Receivers a piece of matter combustible dry and black experience declaring things of that colour to be most easily kindled carefully closing the Vessel we
these together fall somewhat short of the weight which we lately mention'd the resistance of the Air to have held suspended in the cavity of the Cylinder And though as hath been already acknowledg'd we cannot peradventure obtain by the recited means so exact an account as were to be wish'd of what we would discover Yet if it serve us to ground Conjectures more approaching to the Truth then we have hitherto met with I hope it will be consider'd which a famous Poet judiciously says Est quoddâ—m prodire tenus si non datur ultra Peradventure it will not be impertinent to annex to the other Circumstances that have been already set down concerning this Experiment That it was made in Winter in Weather neither Frosty nor Rainy about the change of the Moon and at a place whose latitude is near about 51d and a half For perhaps the force or pressure of the Air may vary according to the Seasons of the Year the temperature of the Weather the elevation of â—he Pole or the phases of the Moon 〈◊〉 or even any of them seeming capable to alter either the heighth or consistence of the incumbent Atmosphere And therefore it would not be amiss if this Experiment were carefully tryd at several times and places with variety of Circumstances It might also be try'd with Cylinâ—ers of several Diameters exquisitely fitted with Suckers that we might know what proportion several Pillars of the Atmosphere bear to the Weights they are able to sustain or lift up and consequently whether the increase or decrement of the resistance of the ambient Air can be reduc'd to any regular proportion to the Diameters of the Suckers These and divers other such things which may be try'd with this Cylinder might most of them be more exactly try'd by the Torricellian Experiment if we could get Tubes so accurately blown and drawn that the Cavity were perfectly Cylindrical To dwell upon all the several Reflections that a speculative Wit might make upon this and the foregoing Experiment I mean the thirty third and thirty second would require almost a Volume whereas our occasions will scarce allow us time to touch upon three or four of the chief Inferences that seem deducible from them and therefore we shall content our selves to point at those few And first as many other Phaenomena of our Engine so especially the two lately mention'd Experiments seem very much to call in question the receiv'd Opinion of the Nature or Cause of Suction For 't is true indeed that when men suck they commonly use some manifest endeavour by a peculiar motion of their Mouthes Chests and some other conspiring parts to convey to them the body to be suckt in And hence perhaps they have taken occasion to think that in all Suction there must be some Endeavour or motion in the sucking to attract the sucked Body But in our last Experiment it appeares not at 〈◊〉 how the upper part of the empty'd Cylinâ—er that remaines moveless all the 〈◊〉 or any part of it does at all enâ—eavour to draw to it the depressed Sucker and the annex'd weights And yet those that behold the ascention of the Sucker without seriously considering the cause of it doe readily conclude it to be rays'd by something that powerfully Sucks or attracts it though they see not what that may be or where it lurks So that it seemes not absolutely necessary to Suction that there 〈◊〉 Body which is said to suck an 〈◊〉 or motion in order thereunto but rather that Suction may be at least for the most part reduc'd to Pulsion and its effects ascrib'd to such a pressure of the neighboring air upon those Bodies whther aërial or of other Natures that are contiguous to the Body that is sayd to attract them as is stronger than that Substance which possesses the cavity of that sucking Body is able to resist To object here that it was some particles of Air remaining in the empty'd Cylinder that attracted this weight to obviate a Vacuum will scarce be satisfactory unless it can be cleerly made out by what litle hooks or other grappling Instruments the internal Air could take hold of the Sucker how so litle of it obtain'd the force to lift up so great a weight and why also upon the letting in of a litle more Air into one of our evacuated Vessels the attraction is instead of being strengthen'd much weaken'd though if there were danger of a Vacuum before it would remain notwithstanding this ingress of a little Air. For that still there remain'd in the capacity of the exhausted Cylinder store of little rooms or spaces empty or devoid of Air may appear by the great violence wherewith the air rushes in if any way be open'd to it And that 't is not so much the decrement of the Vacuum within the cavity of the vessel that debilitates the attraction as the spring of the included air whose presence makes the decrement that does it by resisting the pressure of the external Air seems probable partly from the Disability of vacuities whether greater or lesser to resist the pressure of the Air and partly by some of the Phaenomena of our Experiments and particularly by this Circumstance of the three and Thirtieth that the Sucker was by the pressure of the Ambient Air impellâ—d upwards with its weight hanging at it not only when it was at the bottome of the Cylinder and consequently left a great Vacuum in the cavity of it but when the Sucker had been already impel'd almost to the top of the Cylinder and consequently when the Vacuum that remain'd was become very litle in comparison of that which preceded the beginning of the Sucker's ascention In the next place these Experiments may teach us what to judge of the vulgar Axiom receiv'd for so many Ages as an undoubted Truth in the Peripatetick Schools That Nature abhorres and flys a Vacuum and that to such a degree that no humane power to go no higher is able to make one in the Universe wherein Heaven and Earth would change places and all its other Bodyes rather act contrary to their own Nature than suffer it For if by a Vacuum we will understand a place perfectly devoid of all corporeal Substance it may be indeed then as we formerly noted be plausibly enough maintain'd that there is no such thing in the world but that the generality of the Plenists especially till of late yeares some of them grew more wary did not take a Vacuum in so strict â— Sense may appear by the Experiments formerly and ev'n to this Day imploy'd by the Deniers of a Vacuum to prove it impossible that there can be any made For when they alleadge for Instance that when a man sucks Water through a long Pipe that heavy Liquor contrary to its Nature ascends into the Sucker's mouth only to fill up that room made by the Dilatation of his Brest and Lungs which otherwise will in part be empty And when they tell us that
the Organs And to the Objection to which I foresaw this ghess to be liable namely That no heat intervening there appear'd nothing that should raise the Water into exhalations and give them an impulse I thought it might be said that motion alone if vehement enough may without sensible heat suffice to break Water into very minute parts and make them ascend upwards if they can no where else more easily continue their agitation For I remember that Travelling betwixt Lyons and Geneva I saw not very far out of the Way a place where the River of Rhone coming suddenly to be streighten'd betwixt two Rocks so near each other that a Man may if my Memory fail me not stand astride upon both at once that rapid Stream dashing with great impetuosity against its Rocky Boundaries does break part of its Water into such minute Corpuscles and put them into such a motion that Passengers observe at a good distance off as it were a Mist arising from that place and ascending a good way up into the Air. Such I say was my suspicion touching the Wind we have been considering but it seems something odde that aqueous Vapors should like a dry Wind pass through so long and tortuous a Pipe of Lead as that describ'd by our Author since we see in the Heads of Stills and the Necks of Aeolipiles how quickly such vapors are even by a very little cold recondensed into Water But to this also something may be speciously reply'd wherefore contenting my self to have mention'd our Authors Experiment as a plausible though not demonstrative proof that Water may be transmuted into Air. We will pass on to mention in the third place another Experiment which we try'd in order to the same enquiry We took a clear Glass bubble capable of containing by ghess about three Ounces of Water with a Neck somewhat long and wide of a Cylindrical form this we fill'd with Oyl of Vitriol and fair water of each almost a like quantity and casting in half a dozen small Iron Nails we stopt the mouth of the Glass which was top-full of Liquor with a flat piece of Diapalma provided for the purpose that accommodating it self to the surface of the water the Air might be exquisitely excluded and speedily inverting the Viol we put the Neck of it into a small wide-mouth'd Glass that stood ready with more of the same Liquor in it to receive it As soon as the neck had reach'd the bottom of the Liquor it was dipp'd into there appear'd at the upper part which was before the bottom of the Viol a bubble of about the bigness of a Pea which seem'd rather to consist of small and recent bubbles produc'd by the action of the dissolving Liquor upon the Iron then any parcel of the external Air that might be suspected to have got in upon the inversion of the Glass especially since we gave time to those little Particles of Air which were carried down with the Nails into the Liquor to fly up again But whence this first bubble was produced is not so material to our Experiment in regard it was so small For soon after we perceiv'd the bubbles produced by the action of the Menstruum upon the Metal ascending copiously to the bubble already named and breaking into it did soon exceedingly increase it and by degrees depress the water lower and lower till at length the substance contain'd in these bubbles possessed the whole cavity of the Glass Viol and almost of its Neck too reaching much lower in the Neck then the surface of the ambient Liquor wherewith the open-mouth'd Glass was by this means almost replenished And because it might be suspected that the depression of the Liquor might proceed from the agitation whereinto the exhaling and imprison'd steams were put by that heat which is wont to result from that action of corrosive salts upon Metals we suffered both the Viol and the open-mouthed Glass to remain as they were in a Window for three or four days and nights together but looking upon them several times during that while as well as at the expiration of it the whole cavity of the Glass bubble and most of its Neck seem'd to be possess'd by Air since by its spring it was able for so long to hinder the expell'd and ambient Liquor from regaining its former place And it was remarkable that just before we took the Glass bubble out of the other Glass upon the application of a warm hand to the convex part of the bubble the Imprison'd substance readily dilated it self like Air and broke through the Liquor in divers bubbles succeeding one another Having also another time try'd the like Experiment with a small Viol and with Nails dissolv'd in Aquafortis we found nothing incongruous to what we have now deliver'd And this Circumstance we observ'd that the newly generated steams did not onely possess almost all the whole cavity of the Glass but divers times without the assistance of the heat of my hand broke away in large bubbles through the ambient Liquor into the open Air So that these Experiments with corrosive Liquors seem'd manifestly enough to prove though not that Air may be generated out of the Water yet that in general air may be generated anew Lastly to the foregoing Arguments from Experience we might easily subjoyn the Authority of Aristotle and of his followers the Schools who are known to have taught that Air and Water being Symbolizing Elements in the quality of moisture are easily transmutable into one another But we shall rather to the foregoing Argument adde this drawn from Reason That if as Leucippus Democritus Epicurus and others follow'd by divers modern Naturalists have taught the difference of Bodies proceeds but from the various Magnitudes Figures Motions and Textures of the small parts they consist of all the qualities that make them differ being deducible from thence there appeares no reason why the minute parts of Water and other Bodies may not be so agitated or connected as to deserve the name of Air. For if we allow the Cartesian Hypothesis according to which as we noted at the beginning of this Letter the Air may consist of any terrene or aqueous Corpuscles provided they be kept swimming in the interfluent Celestial Matter it is obvious that Air may be as often generated as Terrestrial Particles minute enough to be carried up and down by the Celestial Matter ascend into the Atmosphere And if we will have the Air to be a congeries of little slender Springs it seems not impossible though it be difficult that the small parts of divers Bodies may by a lucky concourse of causes be so connected as to constitute such little Springs since as we note in another Treatise Water in the Plants it nourishes is usually contriv'd into Springy Bodies and even the bare alter'd position and connexion of the parts of a Body may suffice to give it a Spring that it had not before as may be seen in a thin and
into a new motion and dispos'd after a new manner they did opacate that part of the Air they mov'd in and exhibited a greater whiteness then that which sometimes appears in our Pneumatical Vessel Nor should we content our selves with this single Instance to manifest That little Bodies which being rang'd after one manner are Diaphanous and Colourless may by being barely agitated dispers'd and consequently otherways rang'd exhibite a colour if we were not unwilling to rob our Collection of Experiments concerning Colours But My Lord I foresee You may make some Objections against our proposed ghess which perhaps I shall scarce be able to answer especially if You insist upon having me render a Reason why our Phaenomenon appears not constantly I might indeed answer that probably it would do so if instead of our great Receiver we use such a small Viol as we have lately mention'd wherein the Dissilition of the Air being much greater is like to be the more conspicuous Since I remember not that we ever made our tryal with such small Vessels without finding the expected whiteness to appear But it would remain to be explicated why in our great Receiver the Phaenomenon should sometimes be seen and oftentimes not appear And though that Conjecture which we last made should not be rejected yet if we were further press'd to assign a reason why the Air should abound with such Particles as we there suppose more at one time then another we are not yet provided of any better Answer then this general one That the Air about us and much more that within the Receiver may be much alter'd by such causes as few are aware of For not to repeat those probable Arguments of this Assertion which we have occasionally mention'd here and there in the former part of this Epistle we will here set down two or three Instances to verifie the same Proposition First I finde that the Learned Iosephus Acosta Ioseph Acosta â—at Moâ— Hyst of the Indles lâ—b 3. cap. 9. among other Judicious Observations he made in America hath this concerning the Effects of some Winds There are says he Winds which naturally trouble the Water of the Sea and make it green and black others clear as Crystal Next we have observ'd That though we conveyd into the Receiver our Scales and the Pendula formerly mention'd clean and bright yet after the Receiver had been empty'd and the Air let in again the gloss or lustre both of the one and of the other appear'd tarnish'd by a beginning rust And in the last place we will subjoyn an Observation we made some Years ago which hath been heard of by divers Ingenious Men and seen by some of them We had with pure Spirit of Wine drawn a Tincture out of a certain Concrete which uses to be reckoned among Mineral Bodies And this Tincture being very pure and transparent we did because we put a great value upon it put into a Crystal Viol which we carefully stopp'd and lock'd up in a Press among some other things that we specially priz'd This Liquor being a Chymical Rarity and besides very defecate and of a pleasing Golden Colour we had often occasion to look upon it and so to take notice that one time it seem'd to be very much troubled and not clear as it was wont to be Whereupon we imagined that though it would be something strange yet it was not impossible that some Precipitation of the Mineral Corpuscles was then happening and that thence the Liquor was opacated but finding after some days that though the expected Precipitation had not been made yet the Liquor retaining its former vivid Colour was grown clear again as before we somewhat wondered at it and locking it up again in the same Press we resolved to observe both whether the like changes would again appear in our Tincture and whether in case they should appear they would be ascribable to the alterations of the Weather But though during the greatest part of a Winter and a Spring we took pleasure to observe how the Liquor would often grow turbid and after a while clear again Yet we could not finde that these Mutations depended upon any that were manifest in the Air which would be often dark and clouded when the Tincture was clear and transparent as on the other side in clear Weather the Liquor would appear sometimes troubled and more opacous So that being unable to give an account of these odde changes in our Tincture which we suppose we have not yet lost though we know not whether it have lost its fickle Nature either by those of the Air or any thing else that occurr'd to our thoughts we could not but suspect that there may be in divers Bodies as it were Spontaneous Mutations that is such changes as depend not upon manifest Causes But My Lord what has been all this while said concerning our Phaenomenon is offer'd to You not as containing a satisfactory Account of it but to assist You to give Your self one WE took a Glass Vessel Experiment 38. open at the top and into it we put a mixture of Snow and common Salt such a mixture as we have in another Treatise largely discoursed of and into the midst of this mixture we set a Glasse of a Cylindrical form closely stopp'd at the lower end with Plaister and open at the upper at which we fill'd it with common Water These things being let down into the Receiver and the Pump being set awork the Snow began to melt somewhat faster then we expected whether upon the account of the Exsuction of the Air or because there was but little of the Snow or whether for any other Reason it appeared doubtfull But however by that time the Receiver had been considerably exhausted which was done in lesse then ¼ of an hour we perceived the Water near the bottom of the Glass Cylinder to Freeze and the Ice by a little longer stay seem'd to encrease and to rise somewhat higher then the surface of the surrounding Liquor whereinto almost all the Snow and Salt were resolv'd The Glass being taken out it appear'd that the Ice was as thick as the inside of the Glass it fill'd though into that I could put my Thumb The upper surface of the Ice was very concave which whether it were due to any unheeded accident or to the exsuction of the Air we leave to be determin'd by further tryal And lastly the Ice held against the Light appear'd not destitute of Bubbles though some By-standers thought they were fewer then would have been found if the Water had been frozen in the open Air. The like Experiment we try'd also another time in one of our small Receivers with not unlike success And on this occasion My Lord give me leave to propose a Problem which shall be this Whence proceeds that strange force that we may sometimes observe in frozen Water to break the Bodies that Imprison it though hard and solid That there is such a
Enquiry touching Bubbles made with common and distill'd Water 182 The 24th Experiment wherein the inquiry is prosecuted with other Liquors as with Sallet Oyl Oyl of Turpentine a Solution of Tartar Spirit of Vinegar Red-wine Milk Hen's Eggs Spirit of Urine Spirit of Wine and Water Spirit of Wine 187 c. The wonderful expansion of the Spirit of Wine 194 The 25th Experiment touching the expansion and gravity of the Air under water 195 c. The 26th Experiment touching the Vibrations of a Pendulum 202 c. The 27th Experiment touching the propagation of sound And the Authors intention of trying some other Experiments for the further elucidation thereof 210 c. The 28 Experiment touching the sudden â—ruption of Bubbles from the water when the airs pressure was speedily remov'd 214 The 29 Experiment touching the cause of the ascent of Fumes and Vapors wherein 't is prov'd from the several motions which the Fumes of a strange smoaking Liquor of the Authors were observ'd to have in the Receiver upon the exsuction of the Air that the reason of their ascent proceeds from the gravity of the ambient air and not from any positive levity of their own 217 c. The 30 Experiment concerning the nature of a fluid Body illustrated by the example of smoak which in several circumstances seems very much to resemble the property of a fluid Body 224 c. A conjecture of the cause of the Suns undulation 228 The 31 Experiment concerning the Phaenomena of two flat Marbles exactly plain'd and wrought together and the true reason thereof 229. The Authors intention for the further prosecution thereof what hindred him the reason why the under Marble did not fal from the upper being onely conjoynd with Spirit of Wine when the Receiver was evacuated And a notable relation concerning the cohesion of flat Bodies 231 c. The 32 Experiment touching the forcible pressure of the Air against the outward superficies of a Valve fasten'd upon the stop-cock of the Receiver The Diameter of it and the weight it sustain'd 233 c. The 33 experiment touching the great pressure of the Air against the under superficies of the Sucker 236 c. what weight was requisite to depress it what weight it would lift and carry up with it 239 c. what improvement use there may be made of this experiment 242. A Discourse touching the nature of Suction proving that fuga vacui is not the adequate cause thereof 243 c. The 34th Experiment containing several attempts for the weighing of light Bodies in the exhausted Receiver 258 c. The 35th Experiment touching the cause of â—iltration and the rising of Water in Siphons 262 c. A relation of a new kinde of Siphon of the Authors upon the occasion of trying the Experiment lately observ'd by some French-men and further improv'd by himself and some conjectures touching the cause of the exhibited Phaenomena 267 c. The 36th Experiment touching the weighing of a parcel of Air in the exhausted Vessel and some other Observations for the explication thereof 272 c. An accidental Experiment tending to the further confirmation of the Authors Reflections upon the first Experiment with a digressive Observation noting the subtil penetrancy of some Spirits to exceed by far that of the Air 275 c. And some other Experiments to shew the difficulty of the ingress of the Air into the pores or holes of some bodies into which Water will readily insinuate it self 279 c. with a conjecture at the cause thereof 282. The Author returns to the prosecution of the inquiry after the gravity of the Air But first upon the occasion of the tenacity of a thin Bubble of Glass sets down his thoughts concerning the strange exuperancy of strength in Air agitated by heat above what the same has unagitated 283 c. And then proceeds to the examination of the weight of the Air by an Aeolipile and compares the result thereof with that of Mersennus 286. The Opinions and Experiments of divers Authors and some of his own touching the proportion of weight betwixt Water and Air are compar'd and examin'd by the Author 288. The result thereof 290. Mersennus his observation reconcil'd with that of the Author and the proportion between the gravity of Water and Air about London 291 c. After the recital of the Opinions of several Writers touching the proportion of gravity between Water and Quick silver the Author sets down his own tryals made several ways together with his conclusion therefrom 293 c. The use he makes of this inquiry for the ghessing at the height of the Atmosphere 297. What other Experiments are requisite to the determination thereof 299 c. The 37th Experiment touching the strange and odde Phaenomenon of the sudden flashes of light in the cavity of the Receiver the several circumstances and difficulties of it with some attempts towards the rendering at reason thereof 301 c. The Difficulty of so doing further shewn from the consideration of the various changes of Air which doe not immediatly fall under our senses 315. this last proposition prou'd by severall observations 316. The 38. Experiment touching the freezing of water 319. c. A problem concerning the great force wherewith a freezing Liquor extends its selfe propos'd upon the Consideration of divers admirable effects wrought thâ—reby 320 c. The 39. Experiment containing an inquisition after the temperature of the substance that remain'd in the cavity of the Receiver after the Air was well exhausted The relation of a Phaenomenon seeming to proceed from the swâ—lling of the Glass With an advertisement concerning the pliableness of Glass in small prices 322. c. The 40. Experiment touching the difficulty that occur'd in making tryall whether rarified Air were able to sustaine flying insects 326. c The 41. Experiment Exhibiting severall tryalls touching the respiration of divers sorts of animalls included in the Receiver 328 c. With a digression conteining some doubts touching respiration wherein are delivereâ— severall Experiments relating thereunto 335 c. The 42. Experiment touching the differing operation of corrosive Liquors in the emptied Receiver and in the open Air. 384 The 43. Experiment touching the spontaneous Ebullition of warm Liquors in the exhausted Receiver 388 The Conclusion 394 TO THE LORD OF DVNGARVAN My Honoured and Dear NEPHEW My Dear Lord REceiving in your last from Paris a desire that I would adde some more Experiments to those I formerly sent You over I could not be so much your Servant as I am without looking upon that Desire as a Command and consequently without thinking my self obliged to consider by what sort of Experiments it might the most acceptably be obey'd And at the same time perceiving by Letters from some other Ingenious Persons at Paris that several of the Virtuosi there were very intent upon the examination of the Interest of the Ayr in hindring the descent of the Quick-silver
a very diligent Examiner of the Phaenomena of Wind-Guns would have us believe that in one of them by condensation he reduc'd the Air into a space at least eight times narrower then it before possest And to this if we adde a noble Phaenomenon of the Experiment De Vacuo these things put together may for the present suffice to countenance our Doctrine For that noble Experimenter Monsieur Pascal the Son had the commendable Curiosity to cause the Torricellian Experiment to be try'd at the foot about the middle and at the top of that high Mountain in Auvergne if I mistake not commonly call'd Le Puy de Domme whereby it was found That the Mercury in the Tube fell down lower about three inches at the top of the Mountain then at the bottom And a Learned Man a while since inform'd me That a great Virtuoso friend to us both has with not unlike success tryed the same Experiment in the lower and upper parts of a Mountain in the West of England Of which the reason seems manifestly enough to be this That upon the tops of high Mountains the Air which bears against the restagnant Quick-silver is less press'd by the less ponderous incumbent Air and consequently is not able totally to hinder the descent of so tall and heavy a Cylinder of Quick-silver as at the bottom of such Mountains did but maintain an Aequilibrium with the incumbent Atmosphere And if it be yet further Objected against what hath been propos'd touching the compactness and pressure of the Inferior Air That we finde this very Air to yield readily to the motion of little Flies and even to that of Feathers and such other light and weak Bodies which seems to argue that the particles of our Air are not so compress'd as we have represented them especially since by our former Experiment it appears that the Air readily dilated it self downward from the Receiver into the Pump when 't is plain that it is not the incumbent Atmosphere but onely the subjacent Air in the brass Cylinder that has been remov'd If this I say be objected we may reply That when a man squeezes a Fleece of Wool in his hand he may feel that the Wool incessantly bears against his hand as that which hinders the hairs it consists of to recover their former and more natural extent So each parcel of the Air about the Earth does constantly endeavour to thrust away all those contiguous Bodies whether Aërial or more gross that keep them bent and hinder the expansion of its parts which will dilate themselves or flie abroad towards that part whether upwards or downwards where they finde their attempted Dilatation of themselves less resisted by the neihgboring Bodies Thus the Corpuscles of that Air we have been all this while speaking of being unable by reason of their weight to ascend above the Convexity of the Atmosphere and by reason of the resistance of the surface of the Earth and Water to fall down lower they are forced by their own gravity and this resistance to expand and diffuse themselves about the Terrestial Globe whereby it comes to pass that they must as well press the contiguous Corpuscles of Air that on either side oppose their Dilatation as they must press upon the surface of the Earth and as it were recoyling thence endeavor to thrust away those upper particles of Air that lean upon them And as for the easie yielding of the Air to the Bodies that move in it if we consider that the Corpuscles whereof it consists though of a springy nature are yet so very small as to make up which 't is manifest they doe a fluid Body it will not be difficult to conceive that in the Air as in other Bodies that are fluid the little Bodies it consists of are in an almost restless motion whereby they become as we have more fully discoursed in another Treatise very much disposed to yield to other Bodies In a Discourse touching fluidity and firmness or easie to be displac'd by them and that the same Corpuscles are likewise so variously mov'd as they are intire Corpuscles that if some strive to push a Body plac'd among them towards the right hand for instance others whose motion has an opposite determination as strongly thrust the same Body towards the left whereby neither of them proves able to move it out of its place the pressure on all hands being reduced as it were to an Aequilibrium so that the Corpuscles of the Air must be as well sometimes considered under the notion of little Springs which remaining bent are in their entire bulk transported from place to place as under the notion of Springs displaying themselves whose parts flie abroad whilst as to their entire bulk they scarce change place As the two ends of a Bow shot off fly from one another whereas the Bow it self may be held fast in the Archers hand and that it is the equal pressure of the Air on all sides upon the Bodies that are in it which causes the easie Cession of its parts may be argu'd from hence That if by the help of our Engine the Air be but in great part though not totally drawn away from one side of a Body without being drawn away from the other he that shall think to move that Body too and fro as easily as before will finde himself much mistaken In verification of which we will to divert your Lordship a little mention here a Phaenomenon of our Engine which even to divers ingenious persons has at first sight seem'd very wonderful THe thing that is wont to be admired Experiment 2. and which may pass for our second Experiment is this That if when the Receiver is almost empty a By-stander be desired to lift up the brass Key formerly described as a stopple in the brass Cover he will finde it a very difficult thing to do so if the Vessel be well exhausted and even when but a moderate quantity of Air has been drawn out he will when he has lifted it up a little so that it is somewhat loose from the sides of the lip or socket which with the help of a little oyl it exactly filled before he will I say finde it so difficult to be lifted up that he will imagine there is some great weight fastned to the bottom of it And if as sometimes has been done for merriment onely a Bladder be tyed to it it is pleasant to see how men will marvail that so light a Body filled at most but with Air should so forcibly draw down their hand as if it were fill'd with some very ponderous thing whereas the cause of this pretty Phaenomenon seems plainly enough to be onely this That the Air in the Receiver being very much dilated its Spring must be very much weakn'd and consequently it can but faintly press up the lower end of the stopple whereas the Spring of the external Air being no way debilitated he that a little lifts up
much more or less then one of the twenty six divisions this Air took up By this means after a tryal or two we were inabled to convey to the top of the Glass a bubble of Air equal enough as to sight to one of those Divisions Then the open end of the Tube being put into a small Viol whose bottom was cover'd with Water about half an Inch high we included both Glasses into a small and slender Receiver and caused the Pump to be set awork The event was That at the first exsuction of the Air there appear'd not any expansion of the bubble comparable to what appear'd at the second and that upon a very few exsuctions the bubble reaching as low as the surface of the subjacent Water gave us cause to think that if our Pipe had not been broken it would have expanded it self much further Wherefore we took out the little Tube and found that besides the twenty six divisions formerly mention'd the Glass bubble and some part of the Pipe to which the divided Parchment did not reach amounted to six divisions more Whereby it appears that the air had taken up one and thirty times as much room as before and yet seem'd capable of a much greater expansion if the Glass would have permitted it Wherefore after the former manner we let in another bubble that by our guess was but half as big as the former and found that upon the exsuction of the Air from the Receiver this little bubble did not onely fill up the whole Tube but in part break through the subjacent Water in the Viol and thereby manifest it self to have possessed sixty and odde times its former room These two Experiments are mention'd to make way for the more easie belief of that which is now to follow Finding then that our Tube was too short to serve our turn we took a slender Quill of Glass which happen'd to be at hand though it were no so fit for our purpose as we could have wished in regard it was three or four times as big at one end as the other This Pipe which was thirty Inches long being Hermetically seal'd at the slender end was almost filled with Water and after the above-related manner a bubble was convey'd to the top of it and the open extream was put into a Viol that had a little fair Water at the bottom Then the Cover by means of a small hole purposely made in it for the Glass Pipe to stand out at was cemented on to the Receiver and the Pump being set awork after some exsuctions not onely the Air manifestly appear'd extended below the surface of the subjacent Water but one of the By-standers affirms that he saw some bubbles come out at the bottom of the. Pipe and break through the Water This done we left off Pumping and observ'd how at the unperceiv'd leaks of the Receiver the Air got in so fast that it very quickly impell'd up the Water to the top of the Tube excepting a little space whereinto that bubble was repuls'd which had so lately possess'd the whole Tube this Air at the slender end appear'd to be a Cylinder of â…š parts of an Inch in length but when the Pipe was taken out and turn'd upside down it appear'd at the other end inferior in bulk to a Pea. These things being thus done we took to make the Experiment the more exactly a small pair of Scales such as Gold-Smiths use to weigh Gold Coyn in and weighing the Tube and Water in it we found them to amount to one Ounce thirty Grains and an half Then we pourâ—d in as much Water as serv'd to fill up the Tube wherein before we had left as much space unfill'd up as was possess'd by the bubble and weighing again the Pipe and Water we found the weight increas'd onely by one Grain Lastly pouring out the Water and carefully freeing the Pipe from it which yet we could not perfectly doe we weighed the Glass alone and found it to want two Drachmes and thirty two Grains of its former weight So that the bubble of Air taking up the room but of one Grain in weight of Water it appear'd that the Air by its own 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 was so â—arified as to take up one hundred fifty two times as much room as it did before though it were then compress'd by nothing but the ordinary pressure of the contiguous Air. I know not whether it be requisite to take notice that this Experiment was made indeed in a moist Night but in a Room in whose Chimney there was burning a good Fire which did perhaps somewhat rarifie the Air of which the bubble consisted It has seem'd almost incredible which is related by the Industrious Mersennus That the Air by the violence of heat though as great as our Vessels can support without fusion can be so dilated as to take up seventy times as much room as before Wherefore because we were willing to have a confirmation of so strange a Phaenomenon we once more convey'd into the Tube a bubble of the bigness of the former and prosecuting the Experiment as before with the same Water we observed that the Air did manifestly stretch it self so far as to appear several times a good way below the surface of the Water in the Viol and that too with a surface very convex toward the bottom of the Pipe Nay the Pump being ply'd a little longer the Air did manifestly reach to that place where the bottom of the Tube lean'd upon the bottom of the Viol and seem'd to knock upon it and rebound from it Which Circumstances we adde partly that the Phaenomenon we have been relating may not be imputed to the bare subsiding of the Water that fill'd the Tube upon the taking off the pressure of the ambient Air. And partly also that it may appear that if our Experiments have not been as accurately made as with fitter Instruments might perhaps be possible yet the expansion of the Air is likely to be rather greater then lesser then we have made it Since the Air was able to press away the Water at the bottom of the Pipe though that were about two Inches below the surface of the Water that was then in the Viol and would have been at least as high in the Pipe if the Water had onely subsided and not been depressed So that it seems not unlikely that if the Experiment could be so made as that the expansion of the Air might not be resisted by the Neighboring Bodies it would yet inlarge its bounds and perhaps stretch it self to two hundred times its former bulk if not more However what we have now try'd will I hope suffice to hinder divers of the Phaenomena of our Engine from being distrusted Since in that part of the Atmosphere we live in that which we call the free Air and presume to be so uncompress'd is crouded into so very small a part of that space which if it were not hindred
it would possess We would gladly have tryed also whether the Air at its greatest expansion could be further rarified by heat but do what we could our Receiver leak'd too fast to let us give our selves any satisfaction in that particular Experiment 7. TO discover likewise by the means of that pressure of the Air both the strength of Glass and how much interest the Figure of a Body may have in its greater or lesser Resistance to the pressure of other Bodys we made these further tryals We causd to be blown with a Lamp â— round Glass bubble capable of containing by guess about five Ounces of Water with a slender neck about the bigness of a Swans Quill and it was purposely blown very thin as Viols made with Lamps are wont to be that the thinness of the matter might keep the roundness of the Figure from making the Vessel too strong Then having moderately emptyed the Receiver and taken it out of the Pump we speedily applyed to the Orifice of the bottom of it the Neck of the newly mention'd Glass carefully stopping the Crannys with melted Plaister that no Air might get in at them And after turning the Key of the Stop-cock we made a free passage for the Air to pass out of the bubble into the Receiver which it did with great celerity leaving the bubble as empty as the Receiver it self as appear'd to us by some Circumstances not now to be insisted on Notwithstanding all which the Vessel continuing as intire as before gave us cause to wonder that the bare Roundness of the Figure should inable a Glass almost as thin as Paper to resist so great a pressure as that of the whole incumbent Atmosphere And having reiterated the Experiment we found again that the pressure of the ambient Body thrusting all the parts inwards made them by reason of their arched Figure so support one another that the Glass remain'd as whole as at first Now that the Figure of the Glass is of great moment in this matter may be evinced by this other Experiment Experiment 8. WE took a Glass Helmet or Alembick delineated by the seventh Figure such as Chymists use in Distillations and containing by conjecture between two and three Pints The Rostrum or Nose of it mark'd with c was Hermetically closed and at the top of it was a hole into which was fitted and cemented one of the Shanks of a middle-siz'd Stop-cock so that the Glass being turn'd upside-down the wide Orifice which in common Glass-Helmets is the onely one was upwards and to that wide Orifice was fitted a cast Cover of Lead which was carefully cemented on to the Glass Then the other Shank of the Stop-cock being with Cement likewise fasten'd into the upper part of the Pump the exsuction of the Air was endeavoured But it was not long before the remaining Air being made much too weak to ballance the pressure of the ambient Air the Glass was not without a great noise crack'd almost half round along that part of it where it began to bend inwards As if in the Figure the crack had been made according to the Line ab and upon an endeavour to pump out more of the Air the crack once began appear'd to run on further though the Glass where it was broken seem'd to be by conjecture above ten some thought above twenty times as thick as the bubble mention'd in the foregoing Experiment This will perhaps make it seem strange that having taken another Glass bubble blown at the same time and like for ought we discern'd for size thickness and Figure to that thin one formerly mention'd and having seal'd it up Hermetically and suspended it in the Receiver the exsuction of the ambient Air did not enable the imprisoned Air to break or in the least to crack the bubble though the Experiment were laboriously try'd and that several times with bubbles of other sizes But that perhaps the heat of the Candle or Lamp wherewith such Glasses are Hermetically seal'd not to mention the warmth of his hands that seal'd it might so rarifie the contained Air as much to weaken its Spring may seem probable by the following Experiments Experiment 9. WE took a Glass Viol able to hold three or four Ounces of Water and of the thickness usual in Glasses of that size into the Neck of this was put a moderately slender Pipe of Glass which was carefully fasten'd with a mixture of equal parts of Pitch and Rosin to the Neck of the Viol and which reach'd almost to the bottom of it as the sixth Figure declares This Viol being upon a particular design fill'd with Water till that came up in it a pretty deal higher then the lower end of the Pipe was put into one of our small Receivers containing between a Pint and a Quart in such manner as that the Glass Pipe passing through a hole made purposely for it in the Leaden-Cover of the Receiver was for the most part of it without the Vessel which being exactly closed the Pump was set awork But at the very first exsuction and before the Sucker was drawn to the bottom of the Cylinder there flew out of the Viol a piece of Glass half as broad as the Palm of a Mans Hand and it was thrown out with such violence that hitting against the Neighboring side of the Receiver it not onely dash'd it self to pieces but crack'd the very Receiver in many places with a great noise that much surprised all that were in the Room But it seem'd that in so little a Receiver the Air about the Viol being suddenly drawn out the Air Imprison'd in the Vessel having on it the whole pressure of the Atmosphere to which by the Pipe open at both ends It and the Water were expos'd and not having on the other side the wonted pressure of the Ambient Air to ballance that other pressure the resistance of the Glass was finally surmounted and the Viol once beginning to break where it was weakest the external Air might rush in with violence enough to throw the crack'd parcel so forcibly against the Neighboring side of the Receiver as to break that too And this may be presumed sufficient to verifie what we delivered in that part of our Appendix to the first Experiment where we mention'd the almost equal pressure of the Air on either side of a thin Glass Vessel as the cause of its not being broken by the forcible Spring of the contain'd Air. But yet that it be not suspected that chance had an interest in so odde an Experiment as we have been Relating we will adde that for farther satisfaction we reiterated it in a round Glasse containing by guesse about six ounces of water this violl we put into such a small Receiver as was lately mention'd in such manner as that the bottome of it rested upon the lower part of the Pneumaticall Glasse and the Neck came out through the Leaden-Cover of the same at a hole made purposely for it
erroneousness of the Cartesian Hypothesis concerning the Ebbing and Flowing of the Sea which Des Cartes ascribes to the greater pressure made upon the Air by the Moon and the Intercurrent Ethereal Substance at certain times of the Day and of the Lunary Moneth then at others But in regard we found the Quick-silver in the Tube to move up and down so uncertainly by reason as it seems of accidental mutation in the Air I somewhat doubt whether we shall finde the Altitude of the Quick-silver to vary as regularly as the Experiment is ingeniously propos'd The success we shall God permitting us to make tryal of it acquaint Your Lordship with and in the mean time take notice that when we had occasion to take the Tube out of the Frame after it had staid there part of November and part of December a good Fire being then in the room because it was a Snowy day we found the Quick-silver in the Tube to be above the upper surface of the subjacent Mercury 29 Inches three quarters If Your Lordship should now ask me what are the true causes of this varying altitude of the Mercurial Cylinder I should not undertake to answer so difficult a question and should venter to say no more then that among divers possible causes to which it may be ascribed it would not be perhaps absurd to reckon these that follow First then we may consider that the Air in the upper part of the Tube is much more rarified and therefore more weak then the external Air as may appear by this among other things That upon the inclining of the Tube the Quick-silver will readily ascend almost to the very top of it and so take up eight or nine tenth parts and perhaps more of that space which it deserted before which would not happen if that whole space had been full of unrarified Air since that as tryal may easily satisfie you would not have suffer'd it self to be thrust into so narrow a room by so weak a pressure So that although in our Tube when the included Air was heated the Quick-silver was somewhat depress'd Yet there is this difference betwixt such a Tube and common Weather-Glasses that in these the included and the ambient Air are in an Aequilibrium as to pressure and the weight of the Water that keeps them separate is scarce considerable Whereas in such a Tube as we are speaking of the Air within is very much more dilated then that without and 't is not so much the spring or resistance of the included Air as the weight of the Mercurial Cylinder it self that hinders the Quick-silver from ascending higher for if we should suppose that deserted part of the Tube perfectly devoid of Air yet would the Quick-silver rise but a little higher in it and be far from filling it in regard the outward Air would not be able to impel up such a weight much higher whereas it may by our former Experiments appear that if all the Air in the upper part of a Weather-Glass were away the Water would be impell'd up to the very top of it though the Pipe were above thirty Foot long We may next consider that this rarified Air at the upper part of our Tube being exactly shut up betwixt the Glass and the Quick-silver it was scarce subject to any discernable alterations save those it receiv'd from heat and cold And we may further consider that yet the external Air or Atmosphere is subject to many alterations besides them that proceed from either of those Qualities For the Experiment that occasion'd this Discourse seems to make it probable enough that there may be strange Ebbings and Flowings as it were in the Atmosphere or at least that it may admit great and sudden Mutations either as to its Altitude or its Density from causes as well unknown to us as the effects are unheeded by us And that You may not think that there is nothing in Nature but our Experiment that agrees with this our conjecture we might put Your Lordship in minde of the Pains and Aches that are often complain'd of by those that have had great Wounds or Bruises and that doe presage great Mutations in the Air oftentimes whilst to strong and healthy Persons no sign of any such thing appears And that is also very memorable to this purpose which I remember I have somewhere read in a Book of the Ingenious Kircherus who giving a pertinent admonition concerning the various refractions that may happen in the Air relates That during his stay in Malta he often saw Mount Aetna though the next day notwithstanding its being extreamly clear he could not see it adding that Vintemillius a very Learned Person did oftentimes from a Hill he names behold the whole Island he calls Luprica protuberant above the Sea though at other times notwithstanding a clear Sky he could not see it And though perhaps this may be in part ascribed to the various light position of the sun or to the various disposition of the Spectators eye or peradventure to some other cause yet the most probable cause seems to be the differing Density of the Air occasion'd by Exhalations capable to increase the refraction and consequently bring Beams to the Eye which otherwise would not fall on it We have likewise in another Treatise mention'd our having often observ'd with Telescopes a plenty of Steams in the Air which without such a help would not be taken notice of and which as they were not at all times to be seen even through a Telescope so they did sometimes especially after a shower of Rain hastily disappear and when we have visited those places that abound with Mines we have several times been told by the Diggers that even when the Sky seem'd clear there would not seldom suddenly arise and sometimes long continue a certain Steam which they usually call a damp so gross and thick that it would oftentimes put out their very Candles if they did not seasonably prevent it And I think it will easily be granted that the ascension of such Steams into this or that part of the Air and their mixing with it are very like to thicken it as on the other side either heat or the sudden condensation of the Air in another part of the Atmosphere to mention now no other causes are capable of rarifying it Nor will it very much import the main scope of our Discourse whether it be suppos'd that the copious Steams the earth sends into the air thicken that part of the Atmosphere that receives them and make it more heavy Or that sometimes the Fumes may ascend with such celerity that though the Air be thicken'd yet they rather diminish then encrease its gravitation in regard that the quickness of their ascent not onely keeps them from gravitating themselves but may hinder the pressing downwards of many Aërial Corpuscles that they meet with in their way upwards This I say is of no great importance to our present Discourse since
the juncture there was setled a round whitish Spot or two which at first we thought might be some stain upon the Glass but after finding it to be in divers Qualities like the Oyl and Salt of the Concrete we were Distilling we began to suspect that the most subtle and fugitive parts of the impetuously ascending Steams had penetrated the substance as they speak of the Glass and by the cold of the ambient Air were condens'd on the surface of it And though we were very backward to credit this suspition and therefore call'd in an Ingenious Person or two both to assist us in the Observation and have Witness of its event we continued a while longer to watch the escape of such unctuous Fumes and upon the whole matter unanimously concluded That all things consider'd the subtle parts of the distill'd matter being violently agitated by the excessive heat had pass'd through the Pores of the Glass widen'd by the same heat But this having never happen'd but once in any of the Distillations we have either made or seen though these be not a few it is much more reasonable to suppose that the perviousness of our Receiver to a Body much more subtle then Air proceeded partly from the looser Texture of that particular parcel of Glass the Receiver was made of for Experience has taught us that all Glass is not of the same compactness and solidity and partly from the enormous heat which together with the vehement agitation of the penetrant Spirits open'd the Pores of the Glass then to imagine that such a substance as Air should be able to permeate the Body of Glass contrary to the testimony of a thousand Chymical and Mechanical Experiments and of many of those made in our Engine especially that newly recited Nay by our fifth Experiment it appears that a thin Bladder will not at its Pores give passage even to rarified Air. And on this occasion we will annex an Experiment which has made some of those we have acquainted with it doubt whether the Corpuscles of the Air be not lesse subtle then those of Water But without examining here the reasonablenesse of that doubt we will proceed to recite the Experiment it self which seems to teach That though Air when sufficiently compress'd may perchance get entrance into narrower holes and crannies then Water yet unless the Air be forc'd in at such very little holes it will not get in at them though they may be big enough to let Water pass through them The Experiment then was this I took a fair Glass Siphon the lower end o◠whose longest Leg was drawn by degrees to such a slenderness that the Orifice at which the Water was to fall out would hardly admit a very small Pin This Siphon being inverted the matter was so order'd that a little Bubble of Air was intercepted in the slenderest part of the Siphon betwixt the little hole newly mention'd and the incumbent Water upon which it came to pass that the Air being not to be forc'd through so narrow a passage by so light a Cylinder of Water though amounting to the length of divers Inches as lean'd upon it hinder'd the further Efflux of the Water as long as I pleas'd to let it stay in that narrow place whereas when by blowing a little at the wider end of the Siphon that little parcel of Air was forc'd out with some Water the remaining Water that before continu'd suspended began freely to drop down again as formerly And if you take a Glass Pipe whether it be in the form of a Siphon or no that being for the most part of the thickness of a Mans Finger is yet towards one end so slender as to terminate in a hole almost as small as a Horse-hair and if you fill this Pipe with Water you will finde that Liquor to drop down freely enough thorow the slender Extream But if you then invert the Pipe you will finde that the Air will not easily get in at the same hole through which the Water pass'd For in the sharp end of the Pipe some Inches of Water will remain suspended which 't is probable would not happen if the Air could get in to succeed it since if the hole were a little wider the Water would immediatly subside And though it be true that if the Pipe be of the length of many Inches a great part of the Water will run down at the wider Orifice yet that seems to happen for some other reason then because the Air succeeds it at the upper and narrow Orifice since all the slender part of the Pipe and perhaps some Inches more will continue full of Water And on this occasion I remember that whereas it appears by our fifth Experiment That the Aërial Corpuscles except perhaps some that are extraordinarily fine will not passe thorow the Pores of a Lambs Bladder yet Particles of Water will as we have long since observ'd and as may be easily try'd by very closely tying a little Alcalizate Salt we us'd the Calx of Tartar made with Nitre in a fine Bladder and dipping the lower end of the Bladder in Water for if you hold it there for a competent while you will finde that there will strain thorow the Pores of the Bladder Water enough to dissolve the Salt into a Liquor But I see I am slipt into a Digression wherefore I will not examine whether the Experiment I have related proceeded from hence That the springy Texture of the Corpuscles of the Air makes them less apt to yield and accommodate themselves easily to the narrow Pores o◠Bodies then the more flexible Particles of Water or whether it may more probabiy be ascrib'd to some other Cause Nor will I stay to consider how far we may hence be assisted to ghess at the cause of the ascension of Water in the slender Pipes and Siphons formerly mention'd but will return to our Bubble and take notice That we thought fit also to endeavor to measure the capacity of the Bubble we had made use of by filling it with Water that we might the better know how much Water answered in weight to ¾ of a Grain of Air but notwithstanding all the diligence that was used to preserve so brittle a Vessel it broke before we could perfect what we were about and we were not then provided of another Bubble fit for our turn The haste I was in My Lord when I sent away the last Sheet made me forget to take notice to you of a Problem that occurr'd to my thoughts upon the occasion of the slow breaking of the Glass Bubble in our evacuated Receiver For it may seem strange since by our sixth Experiment it appears that the Air when permitted will by its own internal Spring expand it selfe twice as much as Mersennus was able to expand it by the heat even of a candent Aeolipile Yet the Elater of the Air was scarce able to break a very thin Glass Bubble and utterly unable to break one
Friend that just then came to visit me an Ingenious By-stander thought he perceiv'd some new kind of Light in the Receiver of which giving me hastily notice my Friend and I presently observ'd that when the Sucker was drawn down immediately upon the turning of the Key there appear'd a kinde of Light in the Receiver almost like a faint flash of Lightening in the Day-time and almost as suddenly did it appear and vanish Having not without some amazement observ'd divers of these Apparitions of Light we took notice that the Day was clear the hour about ten in the Morning that the onely Window in the Room fac'd the North and also that by interposing a Cloak or any opacous Body between the Receiver and the Window though the rest of the Room were sufficiently enlightned yet the flashes did not appear as before unless the opacous Body were remov'd But not being able on all these Circumstances to ground any firm Conjecture at the cause of this surprising Phaenomenon as soon as Night was come we made the Room very dark and plying the Pump as in the Morning we could not though we often try'd find upon the turning of the Key so much as the least glimmering of Light whence we inferr'd that the flash appearing in the Receiver did not proceed from any new Light generated there but from some reflections of the light of the Sun or other Luminous Bodies plac'd without it though whence that Reflection should proceed it pos'd us to conjecture Wherefore the next Morning hoping to inform our selves better we went about to repeat the Experiment but though we could as well as formerly exhaust the Receiver though the place wherein we made the tryal was the very same and though other Circumstances were resembling yet we could not discover the least appearance of Light all that Day nor on divers others on which tryal was again fruitlesly made nor can we to this very time be sure a Day before hand that these Flashes will be to be seen in our great Receiver Nay having once found the Engine in a good humour if I may so speak to shew this trick and sent notice of it to our Learned Friend Doctor Wallis who express'd a great desire to see this Phaenomenon though he were not then above a Bow-shoot off and made haste to satisfie his Curiosity yet by that time he was come the thing he came for was no longer to be seen so that having vainly endeavored to exhibit again the Phaenomenon in his presence I began to apprehend what he might think of me when unexpectedly the Engine presented us a flash and after that a second and as many more as suffic'd to satisfie him that we might very well confidently relate that we have our selves seen this Phaenomenon though not confidently promise to shew it others And this unsuccessfulness whereto our Experiment is lyable being such that by all our watchfulness and tryals we could never reduce it to any certain Rules or Observations since in all constitutions of the Weather times of the Day c. it will sometimes answer and sometimes dis-appoint our Expectations We are much discourag'd from venturing to frame an Hypothesis to give an account of it which if the Experiment did constantly succeed might the more hopefully be attempted by the help of the following Phaenomena laid together some of them produc'd upon tryals purposely made to examine the validity of the conjectures other tryals had suggested First then we observ'd that the Apparition of Light may be made as well by Candle-light as by Day-light and in whatever position the Candle be held in reference to the Receiver as on this or that hand of it above it beneath it or any other way provided the Beams of Light be not hinder'd from falling upon the Vessel Next we noted that the flash appears immediately upon the turning of the Key to let the Air out of the Receiver into the empty'd Cylinder in so much that I remember not that when at any time in our great Receiver the Stop-cock was open'd before the Cylinder was exhausted whereby it came to pass that the Air did rather descend then rush into the Cylinder the often mention'd flash appear'd to our eyes Yet we further observ'd that when instead of the great Receiver we made use of a small Glass not containing above a pound and a half of Water the Phaenomenon might be exhibited though the Stop-cock were open provided the Sucker were drawn nimbly down We noted too that when we began to empty the Receiver the appearances of Light were much more conspicuous then towards the latter end when little Air at a time could pass out of the Receiver We observ'd also that when the Sucker had not been long before well Oyl'd and instead of the great Receiver the smaller Vessel above-mention'd was employ'd We observ'd I say that then upon the opening of the Stop-cock as the Air descended out of the Glass into the empty'd Cylinder so at the same time there ascended out of the Cylinder into the Vessel a certain Steam which seem'd to consist of very little Bubbles or other minute Corpuscles thrown up from the Oyl rarefied by the attrition it suffered in the Cylinder For at the same time that these Steams ascended into the Glass some of the same kinde manifestly issued out like a little Pillar of Smoke at the Orifice of the Valve when that was occasionally open'd And these Steams frequently enough presenting themselves to our view we found by exposing the Glass to a clear Light that they were wont to play up and down â—n it and so by their whiteishness to emulate in some measure the apparition of Light For we likewise sometimes found by watchful observation that when the Flash was great not onely at the very instant the Receiver lost of its transparency by appearing full of some kinde of whitish substance but that for some short time after the sides of the Glass continued somewhat opacous and seem'd to be darken'd as if some whitish Steam adher'd to the inside of them He that would render a Reason of the Phaenomenon whereof all these are not all the Circumstances must doe two things whereof the one is difficult and the other little less then impossible For he must give an Account not onely whence the appearing whiteness proceeds but wherefore that whiteness does sometimes appear and sometimes not For our part we freely confesse our selves at a losse about rendering a Reason of the less difficult part of the Problem And though Your Lordship should ev'n press us to declare what Conjecture it was that the above-recited Circumstances suggested to us we should propose the thoughts we then had no otherwise then as bare Conjectures In case then our Phaenomenon had constantly and uniformly appear'd we should have suspected it to have been produc'd after some such manner as follows First we observ'd that though that which we saw in our Receiver seem'd to be some kinde
which till I disabus'd Her She and Her Friends look'd upon as Portentous And such Observations are the more credible because not onely Houswives but more judicious Persons mention it as no very unfrequent thing to hear the Chick Pip or Cry in the Egg before the Shell be broken But this I mention but as a probable not a cogent Argument till I can discover whether an Elision of an halituous Substance though noe true Air may not at the top of the Larynx produce a Sound since I find that the Blade of a Knife held in severall postures in the streame of Vapors or rarified Water that issu's out of an Aeolipile will afford various and very audible Sounds I had thoughts of conveying into our Receiver young ones ripped out of the wombe of their Dammes with their involving Coates intire but could not procure them And I have also had thoughts of trying whether it be not practicable to make a Receiver though not all of glasse yet with little glasse windows so placed that one may freely look into it capacious enough to hold a Man who may observe severall things both touching Respiration and divers other matters and who in case of fainting may by giving a signe of his weaknesse be immediately reliev'd by having air let in upon him And it seems not impossible but that by accustomance some Men may bring themselves to support the want of Air a pretty while since we see that divers will live so much longer then other Men under Water that those that dive for Pearles in the West Indies are said to be able to stay a whole houre under water And Cardan tels us of one Colanus a Diver in Sicily who was able to continue if Cardan neither mistake Cardan de Subtilitat lib. 11. nor impose upon us three or foure times as long Not to mind Your Lordship that You have Your selfe often seen in England a corpulent Man who is wont to descend to the bottome of the Thames and bring out of the deep holes at the bottome of the bankes large fishes alive in his hands lib 3. c. 15. And Acosta tels us he saw in Peru the like manner of fishing but more difficult practised by the Indians I made mention of some Men and of Accustomance because there are but very few who though they use themselves to it by degrees are fit to support for many Minutes the want of Air. Insomuch that an ingenious Man of my acquaintance who is very famous for the usefull skill of drawing Goods and ev'n Ordnance out of sunke Ships being asked by mee how long he was able to continue at the depth of 50. or 60. feet under water without the use of Respiration confessed to mee that hee cannot continue above two minutes of an houre without resorting to the Air which he carries downe with him in a certaine Engine whereof I can show your Lordship a Description Another thing I also learn'd of him by enquiry that was not despicable For asking him whether he found any use of chawing little sponges dipt in oyle in his Mouth when he was perfectly under water and at a distance from his Engine he told me that by the help of these sponges he could much longer support the want of his wonted Respiration then he was able to do without them The true cause of which would perhaps if discovered teach us some thing pertinent to the Probleme touching the Respiration of Fishes But the necessity of Air to the most part of Animals unaccustom'd to the want of it may best be judg'd of by the following Experiments which we try'd in our Engine to discover whether Insects themselves have not either Respiration or some other use of the Air equivalent thereunto We tooke then an humble-bee one of those common flyes that are call'd flesh flyes and one of those hairy wormes that resemble caterpillars and are wont to be call'd Palmer-wormes These three wee convey'd into one of our small Receivers and observ'd to the great wonder of the Beholders that not onely the Bee and the Fly fell downe and lay with their bellies upwards but the worme it selfe seem'd to be suddenly struck dead all of them being reduc'd to lye without motion or any other discernable signe of life within somewhat lesse if we mistake not then one minute of an houre And this notwithstanding the smalnesse of the Animals in proportion to the capacity of the vessels which circumstance we the rather mention because we found that the vessell was not free from leaks And to satisfie the Spectators that 't was the absence of the Air that caus'd this great and sudden change we had no sooner re-admitted the Air at the stopcock than all the three Insects began to shew signes of life and little by little to recover But when we had again drawn out the Air their motions presently ceased they fell down seemingly dead as before coÌ„tinuing moveless as long as by continuing to pump the vessell was kept exhausted This invited us thankfully to reflect upon the wise goodnesse of the Creator who by giving the Air a spring has made it so very difficult as men find it to exclude a thing so necessary to Animals and it gave us also occasion to suspect that if Insects have no lungs nor any part analogous thereunto the ambient Air affects them and relieves them at the Pores of their Skin it not being irrational to extend to these Creatures that of Hippocrates who says That a Living Body is throughout perspirable or to use his expression 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 dispos'd to admit and part with what is Spirituous Which may be somewhat Illustrated by what we have elsewhere noted That the moister parts of the Air readily insinuate themselves into and recede from the pores of the Beards of wilde Oates and those of divers other wilde Plants which almost continually wreath and unwreath themselves according to even the light variations of the temperature of the ambient Air. This Circumstance of our Experiment we particularly took notice of that when at any time upon the Ingress of the Air the Bee began to recover the first sign of Life she gave was a vehement panting which appear'd near the Taâ—l Which we therefore mention because we have observ'd the like in Bees drown'd in Water when they first come to be reviv'd by a convenient heat As if the Air were in the one case as proper to set the Spirits and Alimental Juice a moving as heat is in the other and this may perchance deserve a further consideration We may adde That we scarce ever saw any thing that seem'd so much as this Experiment to manifest That even living Creatures Man always excepted are a kinde of curious Engines fram'd and contriv'd by nature or rather the Author of it much more skilfully then our gross Tools and unperfect Wits can reach to For in our present Instance we see Animals vivid and perfectly sound depriv'd immediately of