Learning from the Past Drama, Science, Performance-Reading Material 04-Literature, Study notes for Playwriting and Drama. Massachusetts Institute of Technology (MIT) (MA)

Learning from the Past Drama, Science, Performance-Reading Material 04-Literature, Study notes for Playwriting and Drama. Massachusetts Institute of Technology (MIT) (MA)

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This class explores the creation (and creativity) of the modern scientific and cultural world through study of western Europe in the 17th century, the age of Descartes and Newton, Shakespeare, Milton and Ford. It compare...
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MIT OpenCourseWare http://ocw.mit.edu

21L.016 / 21M.616 Learning from the Past: Drama, Science, Performance Spring 2009

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x56 A Defence of the Dotrine touching the Pat IL. nine experiments which the examiner in the ix!th and 12th chapters reckons up as urged by his. adveraries; yet do not thereby declare my acquiefcing in his explica- tions of thole ph2omena, but only leave both them and fome other things he de- livers about fiphons and the Magdebhg experiments, to be difcourfed by thofe that are more concerned to examine them, contenting myfelf to have fufficiendy difproved the Funiculus which his expofitions fuppofe, and cleared the grounds of explicating fuch.experiments aright.


t ewo Exqelrxats touching the xmeafre of the force of the fpring of air compred ad dilated,

H E other thing, that I would have confidered touching our advcffary's hypo- Pog t a. thefis. is, that it is needlefls. For whereas he denies not, that the air has fome

weight and fpring, but affirms, that it is very infufficient to perform fuch great mar- ters as the counterpoifing of a mercurial cylinder of 29 inches, as we teach that it may; we hall now endeavour to manifeft by experiments purpofely made, that the fpring of the air is capable of doing far more than it is neceffary for us to afcribe to it, to folve the phmnomena of the Torricellian experiment.

Ws took then a long gla-tube, which, by a dexterous hand and the help of a lamnp, was in fuch a manner crooked at the bottom, that the part turned up was almoft pa- rallel to the reft of the tube, and the orifice of this horter leg of the fiphon (if I may fo call the whole inftrurnent) being hermetically ealed, the length of it was divided into inches (each of which was fubdivided into eight parts) by a ftrcight lift of paper, which containing thofe divifions, was carfully paled all along it. Then putting in as much quickfilver as ferved to fill the arch or bended part of the fiphon~ that the mercury fanding in a level might reach in the one leg to the bottom of the divided paper, and juft to the fame height or horizontal ine in the other; we took care, by frequently inclining the tube, fo that the air might freely pail from one leg into the other by the fides of the mercury (we took, I fay, care) that the air at laft included in the ihorter cylinder flould be of the fame laxity with the reft of the air about it. This done, we began to pour quickfilver into the longer leg of the fiphon, which by its weight prefing up that in the horter leg, did by degrees freighten the included air: and continuing this pouring in of quickfilver till the air in the horter leg was by condenfation reduced to take up but half the fpace it poffeffed (I fay, pof- feffed, not filled) before; we caft our eyes upon the longer leg of the glafs, on which was likewife pafted a lift of paper carefully divided into inches and parts, and we ob- ferved, not without delight and fatisfaftion, that the quickilver in that longer part of the tube was 29 inches higher than the other. Now that this obfervation does both very well agree with and confirm our hypothefis, will be eaflily difcerned by him, that takes notice what we teach; and Monfieur Pafchal and our Englilh friend's experiments prove, that the greater the weight is that leans upon the air, the more forcible is its endeavour of dilatation, and confequently its power of refifance (as other fprings a ftronger when bent by greater weights). For this being confidered, it will appear to agree rarely-well with the hypothefis, that as according to it the air in that degree of denfity and correfpondent meafure of refiftance, to which the weight of the incumbent atmofphere had brought it, was able to counterbalance


Chap. 5. S P R N and WE I H T of tbe A R. x57 and reiiit the preffure of a mercurial cylinder of about 29 inches, as we are taught by the Torricellian experiment; fo here the fame air being brought to a degree of denfity about twice as great as that it had before, obtains a fpring twice as ftrong as formerly. As may appear by its being able to fuftain or relift a cylinder of 29 inches in the longer tube, together with the weight of the atmofpherical cylinder, that leaned upon thofe 29 inches of mercury; and, as wejuft now inferred from the Torricellian experiment, wasequivalent to them.

WE were hindered from profecuting the trial at that time by the cafual breaking of the tube But becaufi an accurate experiment of this nature would be of great importance to the do&rine of the fpring of the air, and has not yet been made (that I know) by any matl; and becaufe alfo it is more uneafy to be made than one would think, in regard of the difficulty as well of procuring crooked tubes fit for the purpofe, as of making a ut entimate of the true place of the protuberant mercury's

urface; I fup e it will not be unwelcome to the reader, to be informed, that after fome other trials, one of which we made in a tube whofe longer leg was perpendi- cular, and the other, that contained the air, parallel to the horizon, we at hla procured a tube of the figure exprcft in the fcheme; which tube, though of a pretty $a S si

bine was fo long, that the cylinder, whereof the fhorter leg of it confifted, ad- mitted a lit of paper, which. had before been divided into t2 inches and their quarters; and the longer leg admitted another lid of paper of divers feet in length, and divided after the fame manner. Then quickfilvcr being poured in to fill up the bended part of the glafs, that the iurface of it in either leg might ref in the fame horizontal line, as we lately taught, there was more and more quickflilver poured into the longer tube; and notice being watchfully taken how far the mercury was rifen in that longer tube, when it appeared to have afcended to any of the divifions in the hotter tube, the feveral obfervations, that were thus fuccdelively made, and as they were made ftdown, afforded us the enfuing table:



A Defence of tk Dorinm toucbig the PrtII .

d nk of tbhe cnkfsm of H4air.

29A 30-

33 35-& 37 39 +.X

44 47-r 540-

5844 6ir

7044 744 77 "' 82 874 93-h

107-:" i17 T




33. 35-- 364T 38. 41T-1


50- 53-i- 58r 604 63-A 664 70-- 73' 1

77a 82a 8 7 T

93, 99T

1O7-, 164T

d. The number of equal fpaces in the thorter leg, that contained the fame parcel of air diverfly extended.

B. The height of th e mercu- rial cylinder in the longer leg, that compreffed the air into thofe dimenfions.

C. The height of the mercu- rial cylinder, that counter- balanced the prefiure of the atmosphere.

D. The aggregate of the two laft columns B and C, exhi- biting the preffure fuftain- ed by the included air.

E. What that prffure fhould be according to the hypo- thefis, that fuppoes the preffures and expanfions to be in reciprocal propor- tion.

FOR the better underfLanding of this experiment, it may not be amifi to take no- tice of the following particulars:

2. THAT the tube being fo tall, that we could not conveniently make ufe of it in a chamber, we were fain to ufe it on a pair of ftairs, which yet were very lightfome, the tube being for prefervation's fake by ftrings fo fufpended, that it did fcarce touch the box prefently to be mentioned.

2. THE lower and crooked part of the pipe was placed in a fquare wooden box, of a good largenefs and depth, to prevent the los of the quicklilver, that might fall afide in the transfufion from the veffel into the pipe, and to receive the whole quick- fiver in cafe the tube fhould break.

3. THAT we were two to make the observation together, the one to take notice at the bottom, how the quickilver rofe in the fhorter cylinder, and the other to pour in at the top of the longer; it being very hard and troublefome for one man alone to do both accurately.

4. That the quickfdver was poured in but by little and little, according to the diredion of him that obferved below; it being far eaier to pour in more, than to take out any, in cafe too much at once had been poured in.



e ¢4,IE

I'd0la la


48 i46

44 42 40 38

36 34 32 30 28 26 24 23 2.2

21 20 19 i.8

'7 z6

15 '14

12 12




toIO 9" 9

8s 8 7- 7 6 6


4; 4' 4: 44

*1 3.




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291V 32-h 34{4 374 41-? 45-- 4*44 34

63 7- Is j38 -


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[60o A Defence of the Do&7rine touching te Part I. meaiures of trength to be met with in the air's fpring, according to its various degrees of compreflion and laxity. But, before I enter upon this fubjeo, I ihall readily ac- knowledge, that I had not reduce the trials I had made about meafuring the ex- panlion of the air to any certain hypothefis, when that ingenious gentleman Mr. Richard lTuml was pleafed to inform me, that having by the perufal of my phyfico- mechanical experiments been fatisfied that the fpring of the air was the caufe of it, he endeavoured (and I wilh in fuch attempts other ingenious men would follow his example) to fupply what I had omitted concerning the reducing to a precife eftirate, how much air dilated of itfelf lofes of its elaflical force, according to the meafures of its dilatation. He added, that he had begun to et down what occurred to him to this purpofe in a hort difcourfe, whereof he afterwards did me the favour to hew me the beginning, which gives me a juft curioity to fee it perfe&ed. But, becaufe I neither know, nor (by reafon of the great diftance betwixt our places of refidence) have at prefent the opportunity to 'inquire, whether he will think fit to annex his difcourfe to our appendix, or to publifh it by itfelf, or at all; and becaufe he hath not yet, for aught I know, met with fit glaffes to make an any-thing-accurate table of the decrement of the force of the dilated air; our prefent defign invites us to prefent the reader with that which follows, wherein I had the afliftance of the fame perfon, that I took notice of in the former chapter, as having written fomething about rarefation: whom I the rather make mention of on this occalion, becaufe when he firft heard me fpeak of Mr. Tawxleys fuppofitions about the proportion, wherein air lofes of its fpring by dilatation, he told me he had the year before (and not long after the publication of my pneumatical treatife) made obfervations to the fame purpofe, which he acknowledged to agree well enough with Mr. Tvzowlq's theory: and fo did (as their author was pleafed to tell me) fome trials made about the fame time by that noble virtuofo and eminent mathematician the Lord Brouncker, from whofe further enquiries into this mattter, if his occalions will allow him to make them, the curious may well hope for omething very accurate.

A table of the rarefalim, of the air.

4. Thenumberofequalfpaces atthe top of the tube, that contained the fame parcel of air.

B. The height of the mercu- rial cylinder, that together with the pring of the in- eluded, air counterbalanced

!: the preffure of the atmof- phere.

,i C. The preffure of the atmof- phere.

D. The complement of B to C, exhibiting the preffure fuRtained by the included air.

E. What that preffiure lhould be, accoring to the hypo- thefis.




3 4 5 6

7 8

9 IC 12

14 16

i8 Ic 24 28




154 20r 22T I 241 I

:a6264 o

27T 2

28l 2846 284 28 41


94 74 3T



24 2a

I' 34I 1, 'I


14T 93 7

5W 44 4

34; 2:: 24It a4





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Chap. 4. SP ING and WRIGHT of the AiR. To make the experiment of the debilitated force of expanded air the plainer, it will

not be amirs to note fome particulars, epecially touching the manner of making the trial; which (for the reafons lately mentioned) we made on a lightfome pair of Rftairs, and with a box alfo lined with paper to receive the mercury that might be fpilt. And in regard it would require a vafi, and in few places procurable quantity of quick- filver, to imploy veffels of fuch kind as are ordinary in the Torricellian experiment, we made ufe of a glafi-tube of about fix feet long; for that being hermetically fealed at one end, ferved our turn as well as if we could have made the experiment in a tub or pond of feventy inches deep.

SECONDLY, We alfo provided a fiender glafs-pipe of about the bignefs of a fwan's quill, and open at both ends; all along which was pafted a narrow lift of paper, divided into inches and half quarters.

THIRDLY, This ender pipe being thruft down into the greater tube almoft filled with quickfilver, the glafs helped to make it fwell to the top of the tube; and the quickfilver getting in at the lower orifice of the pipe, filled it up till the mercury included in that was near about a level with the furface of the furrounding mercury in the tube.

FOuVTHLY, There being, as near as we could gues, little more than an inch of the fender pipe left above the furface of the reftagnant mercury, and confequently unfilled therewith, the prominent orifice was carefully clofed with ealing-wax melted; after which the pipe was let alone for a while, that the air dilated a little by the heat of the wax, might, upon refrigeration, be reduced to its wonted denfity. And then we obferved by the help of the above-mentioned lift of paper, whether we had not included fomewhat more or fomewhat lekl than an inch of air; and in either cae we were fain to reify the error by a fall hole made (with a heated pin) in the wax, and afterwards clofed up again.

FIFTHLY, Having thus included a juRt inch of air, we lifted up the flender pipe by degrees, till the air was dilated to a inch, an inch and an half, two inches, &5c. and obfxrved in inches and eighths the length of the mercurial cylinder, which at each degree of the air's expanfion was impelled above the furface of the relagnant mercury in the tube.

SIxTHLY, The observations being ended, we prefently made the Torricellian expe- riment with the above-mentioned great tube of fix feet long, that we might know the height of the mercurial cylinder, for that particular.day and hour; which height we found to be 29 inches.

SzvzNTHLY, Our-obfervations made after this manner furnished us with the pre- ceding table, in which there would not probably have been found the difference here fet down betwixt the force of the air, when expanded to double its former dimenfions, and what that force hould have been precifely according to the theory, but that the included inch of air received fome little acceflion during the trial which this newly mentioned difference making us fufpe&, we found by replunging the pipe into the quickfiler, that the included air had gained about half an eighth, which we guefed to have come from- fornme little aerial bubbles in the quicklilver, contained in the pipe (o eafy is it in fuch nice experiments to mili of exanefis). We tried alfo with z2 inches of air lhut up to be dilated; but being then hindered by ome unwelcome avocations to profecute thofe experiments, we hall elfewhere, out of other notes and trials (God permitting) fet down fome other accurate tables concerning this matter. By which poffibly we may be aflifed to refolve, whether the atmofphere hould be looked upon (as it ufually is) as a limited and bounded portion of the air; or whether we hould, in a tricer fenfe than we did before, ufe the atmofphere and airial



Defece of the Doetrine toucbhing the Part I. part of the world for almoft equivalent terms; or elfe whether we fhould allow the word atmofphere fome other notion in relation to its extent and limits; (for as to its fpring and weight, thefe experiments do not queftion, but evince them.) But we are willing, as we faid, to refer the matters to our Appendix, and till then to retain our wonted manner of fpeaking of the air and atmofphere. In the mean time (to return to our laCft-mentioned experiments) betides that fo little a variation may be in great part imputed to the difficulty of making experiments of this nature exaily, and perhaps a good part of it to omething of inequality in the cavity of the pipe, or even in the thickners of the glafs; betides this, I fay, the proportion betwixt the feveral preffures of the included air undilated and expanded, efpecially when the dilatation was great (for when the air welled but to four times its firft extent, the mercurial cylinder, though of near 23 inches, differed not a quarter of an inch from what it thould have been according to mathematical exa&ltnefs) the proportion, I fay, was fuitable enough to what might be expe&ed, to allow us to make this refledion upon the whole; that whether or no the intimated theory will hold exaflly (for about that, as faid above, I dare determine nothing refolutely till I have further confidered the matter) yet fince the inch of air, when it was firft included, was hut up with no other preffure than that, which it had from the weight of the incumbent air, and was no more cornpreffed than the reft of the air we breathed and moved in; and fince alfo this inch of air, when expanded to twice its former dimenfions, was able with the help of a mercurial cylinder of about X 5 inches to counterpoise the weight of the atmofphere, which the weight of the external air gravitating upon the reftagnant mercury was able to impel up into the pipe, and fuftain above twenty-eight inches of mercury, when the internal air, by its great expanfion, had its fpring too far debili- tated to make any confiderable (I fay confiderable, for it was not yet fo dilated as not to make fome) refiftance: fince, I fay, there things are fo, the free air here below appears to be almoft as ftrongly compreffed by the weight of the incumbent air, as it would be by the weight of a mercurial cylinder of twenty eight or thirty inches; and confequently is not in fuch a Rate of laxity and freedom as men are wont to imagine; and acts like ome mechanical agent, the decrement of whofe force holds a ftriter proportion to its increafe of dimenfion, than has been hitherto taken notice of.

I MUST not now Rand to propofe the feveral reflections, that may be made upon the foregoing obfervations touching the comprelion and expanfion of air; partly becaufe we could fcarce avoid making the hiforical part omewhat prolix; and partly becaufe I fuppofe we have already faid enough to hew what was intended: namely, that to folve the phenomena there is not of our adverry's hypothefis any need: the evincing of which will appear to be of no finall moment in our prefent controverfy to him that confiders, that the two main things, that induced the learned examiner to reje& our hypothelis, are, that nature abhors a vacuum; and that though the air have Come weight and fpring, yet, thefe are infufficient to make out the known phznomena; for which we mutt therefore have recourfe to his Funiculus. Now as we have formerly feen, that he has not fo fatisfaftorily difproved as refolutely rejete&ed a vacuum fo we have now manifeftced, that the fpring of the air may fuffice to perform greater things than what our explication of the Torricellian experiments and thofe of our engine obliges us to afcribe to it. Wherefore fmce betides the feveral difficulties, that incumber the hypothefis we oppofe, and efpecially its being fcarce, if at all, intelligible, we can add that it is unneceffary; we date expe,, that fuch readers as are not biaffed by their reverence for riJfotle, or the Peripatetick fchools, will hardly rejet an hypothefis, which, betides that it is very intelligible, is.




i I I I


i i


SPRING and WEIGHT f the AIR. cow proved to be fulficient, only to imbrace a do&rine, that fuppofes fuch a rarefac. tion and condenfation, as many'famous Naturalifts reje&ed for its not being compre- henfible, even when they knew of no other way (that was probable) of folving the phenomena wont to be explicated by it.


Wfberein what is oje 7ed againfl Mr. BOYLE' Eplications of particular Experiments, is anfwered.

ND now we are come to the third and lait part of our defence; wherein we are to confider, what our examiner is pleafed to obje& againft fome paffages of

our Phyfico-Mechanical Treatife. But though this may feem the only part, wherein I am particularly concerned; yet perhaps we hall find it, if not the horteft, at leaft the eafiet, part of our talk. Partly, becaufe our author takes no exceptions at the experiments themfelves, as we have recorded them (which from an adversary, wh~ in fome places fipeaks of them as an eye-witnelf, is no contemptible teftimony, that the matters of fa& have been rightly .delivered): and partly, becaufe there are divers experiments which, together with their explications, the examiner has thought fit to leave untouched, and thereby allows us to do fo too: and partly alfo, becaufe that (as to divers of thofe experiments, upon which he animadverts) he does not pretend to fhew, that our explications are ill deduced or incongruous to our prin- ciples; but only that the phenomena may be explained either better, or as well, by his hypothefis; whereof he fuppofes himfelf to have demonftrated the truth, toge- ther with the erroneoufnefs of ours, in the other parts of his book, epecially the third, fourth and fifth chapters. So that after what we have faid to vindicate the hypothefis we maintain, and take away our author's imaginary Funiculus; it will not be requifite for us, on fuch occaions, to examine his particular afertions and expli- cations. Which advertifement we hope the reader will be pleated to bear in mind, and thereby fave himfelf and us the trouble of a great deal of unneceffary repetition. Wherefore, presuming he will do lo, we hall not flay to examine the firft and fecond corollaries, which in this .th chapter he annexes. to the manner of emptying our receiver by our pump. Neither fhould we fay any thing as to his third and laft corollary, but that we think fit to defire the reader to take notice, that according to what he teaches in that place, the more the air is rarefied, the more forcibly it is able to contraf itfelf.

A defence f our fJrf ad cfcond EXPERIMENTS.

A ND to proceed now to his 18th chapter, which he intitles De experirentis L Boyliaxis, we Ihall find, according to what we lately noted, that againft the

firft experiment he obje&s nothing, fave that if one of the fingers- be applied to the orifice of the valve, when the pump is freed from air, the experimenter Mhall feel to his pain, that the fucker is not thruft inward by the external air, but, as the finger,




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