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version 1.5, 2002/06/28 13:03:25

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]><archimedes> <info> <author>Boyle, Robert</author> <title>New Experiments Physico-Mechanicall Touching the Air</title> <date>1660</date> <place>Oxford</place> <editor></editor> <publisher></publisher> <translator></translator> <lang>en</lang> <chunk unit="page*">page</chunk><locator>0000000013</locator> </info> <text> <front> </front> <body> <chap> <pb/>

]><archimedes> <info> <author>Boyle, Robert</author> <title>New Experiments Physico-Mechanicall Touching the Air</title> <date>1660</date>

<place>Oxford</place> <editor></editor> <publisher></publisher> <translator></translator> <lang>en</lang> <chunk unit="page*">page</chunk><locator>0000000013</locator> </info> <text> <front> </front> <body> <chap> <pb/>

<s><emph type="center"/>NEW <lb/><emph type="italics"/>EXPERIMENTS <lb/>Phy&longs;ico-Mechanicall <lb/>Touching the Air.<emph.end type="italics"/><emph.end type="center"/></s><pb/>

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<s><emph type="italics"/>But if it be demanded, why then I did <lb/>not make it f<gap/>ter for the Pre&longs;s before I &longs;ent <lb/>it thither? </s>

<s>my An&longs;wer mu&longs;t be, That not <lb/>at fir&longs;t imagining that this &longs;ort of Experi<lb/>ments would prove any thing near &longs;o trouble<lb/>&longs;ome, either to make, or to Record, as I <lb/>afterwards found them, I did, to engage <lb/>the Printer to di&longs;patch, promi&longs;e him to &longs;end <lb/>him the whole Epi&longs;tle in a very &longs;hort time: <lb/>So that although now and then the occa&longs;ional <lb/>vacations of the Pre&longs;s, by rea&longs;on of Fe&longs;ti-<emph.end type="italics"/><pb/><emph type="italics"/>vals, or the ab&longs;ence of the Corrector, gave <lb/>me the lei&longs;ure to ex&longs;paciate upon &longs;ome &longs;ub<lb/>ject; yet being oftentimes call'd upon to di&longs;<lb/>patch the Papers to the Pre&longs;s, my promi&longs;e, <lb/>and many unexpected Avocations, obliged <lb/>me to a ha&longs;te, which, though it have detract<lb/>ed nothing from the Faithfulne&longs;s of the <lb/>Hi&longs;torical part of our Book, has (I fear) <lb/>been di&longs;advantageous enough to all the re&longs;t. <lb/>And I made the le&longs;s &longs;cruple to let the fol<lb/>lowing Papers pa&longs;s out of my hands, with <lb/>all their Imperfections; becau&longs;e, as the <lb/>publick Affairs, and my own, were then <lb/>circum&longs;tanc'd, I knew not when (if at all) <lb/>I &longs;hould be again in a condition to pro&longs;ecute <lb/>Experiments of this kinde; e&longs;pecially, <lb/>&longs;ince (to omit my being almo&longs;t weary of be<lb/>ing, as it were, confin'd to one &longs;ort of Ex<lb/>periments) I am pre-ingag'd (if it plea&longs;e <lb/>God to vouch&longs;afe me Life and Health) to <lb/>imploy my fir&longs;t lei&longs;ure in the publication of <lb/>&longs;ome other Phy&longs;iological Papers, which I <lb/>thought 'twould make me much the &longs;itter to <lb/>take in hand, if I fir&longs;t di&longs;patch'd all that <lb/>I had at this time to write touching our <lb/>Engine.<emph.end type="italics"/></s>

<s>And I made the le&longs;s &longs;cruple to let the fol<lb/>lowing Papers pa&longs;s out of my hands, with <lb/>all their Imperfections; becau&longs;e, as the <lb/>publick Affairs, and my own, were then <lb/>circum&longs;tanc'd, I knew not when (if at all) <lb/>I &longs;hould be again in a condition to pro&longs;ecute <lb/>Experiments of this kinde; e&longs;pecially, <lb/>&longs;ince (to omit my being almo&longs;t weary of be<lb/>ing, as it were, confin'd to one &longs;ort of Ex<lb/>periments) I am pre-ingag'd (if it plea&longs;e <lb/>God to vouch&longs;afe me Life and Health) to <lb/>imploy my fir&longs;t lei&longs;ure in the publication of <lb/>&longs;ome other Phy&longs;iological Papers, which I <lb/>thought 'twould make me much the &longs;itter to <lb/>take in hand, if I fir&longs;t di&longs;patch'd all that <lb/>I had at this time to write touching our <lb/>Engine.<emph.end type="italics"/></s>

<s><emph type="italics"/>I have this further to adde, by way <lb/>of Excu&longs;e, That as it has been my de&longs;ign <lb/>in publi&longs;hing the&longs;e Experiments to gratifie<emph.end type="italics"/><pb/><emph type="italics"/>Ingenious men; &longs;o, if I have not been <lb/>much flattered, I may hope that the vari<lb/>ous hints to be met with in the following <lb/>Letter, will (at lea&longs;t) &longs;omewhat awaken <lb/>mens thoughts, & excite them to new &longs;pecula<lb/>tions (&longs;uch as perhaps even inqui&longs;itive men <lb/>would &longs;carce el&longs;e light upon) and I need not <lb/>de&longs;pair, that even the examination of &longs;uch <lb/>new Su&longs;picions and Enquiries will hence al<lb/>&longs;o, at lea&longs;t Occa&longs;ionally be facilitated: I <lb/>&longs;aid Occa&longs;ionally, becau&longs;e it being, as 'tis <lb/>proverbially &longs;aid,<emph.end type="italics"/> Facile Inventis addere. <lb/><emph type="italics"/>It &longs;eems not irrational to expect, that our <lb/>Engine it &longs;elf, and divers of our Experi<lb/>ments, will be much promoted by the Indu<lb/>&longs;try of Inventive and Mathematical Wits, <lb/>who&longs;e contrivances may ea&longs;ily either correct <lb/>or &longs;upply, and con&longs;equently &longs;urpa&longs;s many of <lb/>tho&longs;e we have made u&longs;e of. </s>

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<s>And though it may appear <lb/>by &longs;ome of tho&longs;e Writings I &longs;ometimes <lb/>fhew'd your Lord&longs;hip, that I had been &longs;ol<lb/>licitous to try things upon the &longs;ame <lb/>ground; yet in regard this Gentleman <lb/>was before-hand with me in producing <lb/>&longs;uch con&longs;iderable effects, by means of the <lb/>ex&longs;uction of Air, I think my &longs;elf oblig'd <pb pagenum="6"/>to acknowledge the A&longs;&longs;i&longs;tance, and En<lb/>couragement the Report of his perfor<lb/>mances hath afforded me. </s>

<s>But as few inventions happen to be at <lb/>fir&longs;t &longs;o compleat, as not to be either ble<lb/>mi&longs;hd with &longs;ome deficiencies needful to be <lb/>remedy'd, or otherwi&longs;e capable of im<lb/>provement: &longs;o when the Engine we <lb/>have been &longs;peaking of, comes to be more <lb/>attentively con&longs;ider'd, there will appear <lb/>two very con&longs;iderable things to be de<lb/>&longs;ir'd in it. </s>

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<s>But becau&longs;e <lb/>the cementing of this was a matter of <lb/>&longs;ome difficulty, it will not be ami&longs;s to <lb/>mention here the manner of it, which <lb/>was, That the cavity of the tin Plate was <lb/>fill'd with a melted Cement, made of <lb/>Pitch, Ro&longs;in, and Wood-a&longs;hes, well in<lb/>corporated; and to hinder this liquid <lb/>Mixture from getting into the Orifice (Z) <pb pagenum="12"/>of the &longs;hank, (X) that hole was &longs;topt <lb/>with a Cork, to which was fa&longs;tned a &longs;tring, <lb/>whereby it might be pull'd out of the up<lb/>per Orifice of the Receiver; and then, <lb/>the gla&longs;s neck of the Receiver being well <lb/>warm'd, was thru&longs;t into this Cement, and <lb/>over the &longs;hank whereby it was effected, <lb/>that all the &longs;pace betwixt the tin Plate and <lb/>the Receiver, and betwixt the internal <lb/>&longs;uperficies of the Receiver, and the <lb/>&longs;hanck of the Cock, was filld with the <lb/>Cement; and &longs;o we have di&longs;pach'd the <lb/>fir&longs;t and upper part of the Engine. </s>

<s>The undermo&longs;t remaining part con&longs;i&longs;ts <lb/>of a Frame, and of a &longs;ucking Pump, or <lb/>as we formerly call'd it, an Air Pump, &longs;up<lb/>ported by it: The Frame is of Wood, <lb/>&longs;mall, but very &longs;trong, con&longs;i&longs;ting of three <lb/>legs, (111) &longs;o plac'd, that one &longs;ide of <lb/>it may &longs;tand perpendicular, that the free <lb/>motion of the hand may not be hindered. <lb/>In the mid&longs;t of which frame, is tran&longs;ver&longs;ly <lb/>nail'd a board, (222) which may not im<lb/>properly be call'd a Midriff, upon which <lb/>re&longs;ts, and to which is &longs;trongly fa&longs;tned, the <lb/>main part of the Pump it &longs;elf, which is <lb/>the onely thing remaining to be de&longs;cri<lb/>bed. </s>

<s>In the mid&longs;t of which frame, is tran&longs;ver&longs;ly <lb/>nail'd a board, (222) which may not im<lb/>properly be call'd a Midriff, upon which <lb/>re&longs;ts, and to which is &longs;trongly fa&longs;tned, the <lb/>main part of the Pump it &longs;elf, which is <lb/>the onely thing remaining to be de&longs;cri<lb/>bed. </s>

<s>The Pump con&longs;i&longs;ts of four parts, a <pb pagenum="13"/>hollow Cylindre, a Sucker, a handle to <lb/>move that Sucker, and a Valve. </s>

<s>The Cylindre was (by a pattern) ca&longs;t <lb/>of bra&longs;s; it is in length about 14 inches, <lb/>thick enough to be very &longs;trong, notwith<lb/>&longs;tanding the Cylindrical cavity left with<lb/>in it; this cavity is about three inches <lb/>Diameter, and makes as exact a Cylin<lb/>dre as the Artificer was able to bore. <lb/>This hollow Cylindre is fitted with a &longs;uck<lb/>er, (4455) con&longs;i&longs;ting of two parts, the <lb/>one (44) &longs;omewhat le&longs;s in Diameter then <lb/>the cavity of the Cylindre, upon which <lb/>is nail'd a good thick piece of tan'd &longs;hoe <lb/>Leather, which will go &longs;o clo&longs;e to the <lb/>Cylindre, that it will need to be very <lb/>forcibly knock'd and ram'd in, if at any <lb/>time it be taken out, which is therefore <lb/>done, that it may the more exactly hin<lb/>der the Air from in&longs;inuating it &longs;elf be<lb/>twixt it and the &longs;ides of the Cylindre <lb/>whereon it is to move. </s>

<s>This hollow Cylindre is fitted with a &longs;uck<lb/>er, (4455) con&longs;i&longs;ting of two parts, the <lb/>one (44) &longs;omewhat le&longs;s in Diameter then <lb/>the cavity of the Cylindre, upon which <lb/>is nail'd a good thick piece of tan'd &longs;hoe <lb/>Leather, which will go &longs;o clo&longs;e to the <lb/>Cylindre, that it will need to be very <lb/>forcibly knock'd and ram'd in, if at any <lb/>time it be taken out, which is therefore <lb/>done, that it may the more exactly hin<lb/>der the Air from in&longs;inuating it &longs;elf be<lb/>twixt it and the &longs;ides of the Cylindre <lb/>whereon it is to move. </s>

<s>To the mid&longs;t of this former part of the <lb/>Sucker is &longs;trongly fa&longs;tned the other, <lb/>namely a thick and narrow plate of Iron, <lb/>(55) &longs;omewhat longer then the Cylindre, <lb/>one of who&longs;e edges is &longs;mooth, but at the <lb/>other edge it is indented (as I may &longs;o <lb/>&longs;peak) with a row of teeth delineated in <pb pagenum="14"/>the Scheme, into who&longs;e intervals are to <lb/>be fitted, the teeth of a &longs;mall Iron nut; <lb/>(<gap/>) (as Trade&longs;-men call it) which is fa&longs;t<lb/>ned by two &longs;taples (22) to the under &longs;ide <lb/>of the formerly mention'd tran&longs;ver&longs;e <lb/>board (222) on which the Cylindre re&longs;ts, <lb/>and is turn'd to and fro by the third piece <lb/>of this Pump, namely, the handle or <lb/><emph type="italics"/>manubrium,<emph.end type="italics"/> (7) of which the Figure gives <lb/>a &longs;ufficient de&longs;cription. </s>

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<s>And <lb/>la&longs;tly, the bra&longs;s cover of the Receiver, <lb/>being put into the bra&longs;s ring formerly de<lb/>&longs;crib'd, that no Air may get between <lb/>them, it will be very requi&longs;ite to plai&longs;ter <lb/>over very carefully the upper edges of <lb/>both, with the plai&longs;ter formerly mention<lb/>ed, or &longs;ome other as clo&longs;e, which is to be <lb/>&longs;pread upon the edges with a hot Iron; <lb/>that being melted, it may run into and <pb pagenum="16"/>fill up all the crannies, or other little ca<lb/>vities, at which the Air might otherwi&longs;e <lb/>get entrance. </s>

<s>All things being thus fitted, and the <lb/>lower &longs;hank (O) of the &longs;top-cock being <lb/>put into the upper Orifice of the Cylin<lb/>der (&), into which it was exactly ground; <lb/>the Experimenter is fir&longs;t, by turning the <lb/>handle, to force the Sucker to the top of <lb/>the Cylinder, that there may be no Air <lb/>left in the upper part of it: Then &longs;hut<lb/>ting the Valve with the Plug, and turning <lb/>the other way, he is to draw down the <lb/>Sucker to the bottom of the Cylinder; <lb/>by which motion of the Sucker, the Air <lb/>that was formerly in the Cylinder being <lb/>thru&longs;t out, and none being permitted to <lb/>&longs;ucceed in its room, 'tis manife&longs;t that the <lb/>cavity of the Cylinder mu&longs;t be empty, <lb/>in reference to the Air: So that if there<lb/>upon the Key of the Stop-cock be &longs;o <lb/>turn'd, as that through the perforation of <lb/>it, a free pa&longs;&longs;age be opened betwixt the <lb/>Cylinder and the Receiver, part of the <lb/>Air formerly contain'd in the Receiver, <lb/>will nimbly de&longs;cend into the Cylinder. <lb/>And this Air, being by the turning back <lb/>of the Key hinder'd from the returning <lb/>into the Receiver, may, by the opening <pb pagenum="17"/>of the Valve, and forcing up of the Suck<lb/>er to the top of the Cylinder again, be <lb/>driven out into the open Air. </s>

<s>And this Air, being by the turning back <lb/>of the Key hinder'd from the returning <lb/>into the Receiver, may, by the opening <pb pagenum="17"/>of the Valve, and forcing up of the Suck<lb/>er to the top of the Cylinder again, be <lb/>driven out into the open Air. </s>

<s>And thus <lb/>by the repetition of the motion of the <lb/>Sucker upward and downward, and by op<lb/>portunely turning the Key, and &longs;topping <lb/>the Valve, as occa&longs;ion requires, more or <lb/>le&longs;s Air may be &longs;uck'd out of the Recei<lb/>ver, according to the exigency of the Ex<lb/>periment, and the intention of him that <lb/>makes it. </s>

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<s>Such <lb/>are the pre&longs;ervation of Animal and o<lb/>ther Bodies therein, the germination and <lb/>growth of Vegetables, and other tryals <lb/>of &longs;everal &longs;orts, which it is apparent can<lb/>not be well made unle&longs;s the external Air <lb/>can, for a competent while, be excluded: <lb/>Since even at a very &longs;mall leak there may <lb/>enough get in, to make the <emph type="italics"/>Vacuum<emph.end type="italics"/> &longs;oon <lb/>loo&longs;e that name; by which I here declare <lb/>once for all, that I under&longs;tand not a &longs;pace <lb/>wherein there is no body at all, but &longs;uch <lb/>as is either altogether, or almo&longs;t totally <lb/>void of Air. </s>

<s>Now this di&longs;tinction of Experiments <lb/>I thought fit to premi&longs;e to the en&longs;uing <lb/>Narratives, becau&longs;e upon tryal, we found <lb/>it &longs;o exceeding (and &longs;carce imaginable) dif-<pb pagenum="19"/>ficult a matter, to keep out the Air from <lb/>getting at all in at any imperceptible hole <lb/>or flaw what&longs;oever, in a Ve&longs;&longs;el immedi<lb/>ately &longs;urrounded with the compre&longs;&longs;ed At<lb/>mo&longs;phere, that in &longs;pight of all our care <lb/>and diligence, we never were able totally <lb/>to exhau&longs;t the Receiver, or keep it when <lb/>it was almo&longs;t empty, any con&longs;iderable <lb/>time, from leaking more or le&longs;s: although <lb/>(as we have lately intimated) by unwearyed <lb/>quickne&longs;s in plying the Pump, the inter<lb/>nall Air can be much fa&longs;ter drawn out <lb/>then the external can get in, till the Re<lb/>ceiver come to be almo&longs;t quite empty. <lb/>And that's enough to enable men to di&longs;<lb/>cover hitherto unob&longs;erved <emph type="italics"/>Phænomena<emph.end type="italics"/> of <lb/>Nature. </s>

<s>And that's enough to enable men to di&longs;<lb/>cover hitherto unob&longs;erved <emph type="italics"/>Phænomena<emph.end type="italics"/> of <lb/>Nature. </s>

<s>The Experiments therefore of the fir&longs;t <lb/>&longs;ort, will, I fear, prove the onely ones <lb/>wherewith my Avocations will allow me <lb/>to entertain Your Lord&longs;hip in this Letter. <lb/>For till your further Commands &longs;hall en<lb/>gage me to undertake, by Gods permi&longs;<lb/>&longs;ion, &longs;uch an Employment, and more lea<lb/>&longs;ure &longs;hall better fit me for it, I know not <lb/>whether I &longs;hall be in a condition to try <lb/>what may be done, to enable me to give <lb/>you &longs;ome account of the other &longs;ort of <lb/>Experiments al&longs;o. </s><pb pagenum="20"/>

<s>For till your further Commands &longs;hall en<lb/>gage me to undertake, by Gods permi&longs;<lb/>&longs;ion, &longs;uch an Employment, and more lea<lb/>&longs;ure &longs;hall better fit me for it, I know not <lb/>whether I &longs;hall be in a condition to try <lb/>what may be done, to enable me to give <lb/>you &longs;ome account of the other &longs;ort of <lb/>Experiments al&longs;o. </s><pb pagenum="20"/>

<s>TO proceed now to the <emph type="italics"/>Phænomena,<emph.end type="italics"/><lb/><arrow.to.target n="marg2"></arrow.to.target><lb/>exhibited to us by the Engine above <lb/>de&longs;cribed; I hold it not unfit to begin <lb/>with what does con&longs;tantly and regularly <lb/>offer it &longs;elf to our ob&longs;ervation, as depend<lb/>ing upon the Fabrick of the Engine it &longs;elf, <lb/>and not upon the nature of this or that <lb/>particular Experiment which 'tis employ<lb/>ed to try. </s>

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<s>By which <lb/><foreign lang="greek">e)latg\r</foreign> or Spring of the Air, that which <lb/>I mean is this: That our Air either con<lb/>&longs;i&longs;ts of, or at lea&longs;t abounds with, parts of <lb/>&longs;uch a nature, that in ca&longs;e they be bent or <lb/>compre&longs;&longs;'d by the weight of the incum<lb/>bent part of the Atmo&longs;phere, or by any o<lb/>ther Body, they do endeavor, as much as <lb/>in them lies, to free them&longs;elves from that <lb/>pre&longs;&longs;ure, by bearing again&longs;t the contigu<lb/>ous Bodies that keep them bent; and, <lb/>a&longs;&longs;oon as tho&longs;e Bodies are remov'd or <lb/>reduced to give them way, by pre&longs;ently <lb/>unbending and &longs;tretching out them&longs;elves, <lb/>either quite, or &longs;o far forth as the con<lb/>tiguous Bodies that re&longs;i&longs;t them will per<lb/>mit, and thereby expanding the whole <lb/>parcel of Air, the&longs;e ela&longs;tical Bodies com<lb/>po&longs;e. </s><pb pagenum="23"/>

<s>This Notion may perhaps be &longs;ome<lb/>what further explain'd, by conceiving the <lb/>Air near the Earth to be &longs;uch a heap of <lb/>little Bodies, lying one upon another, as <lb/>may be re&longs;embled to a Fleece of Wooll. <lb/>For this (to omit other likene&longs;&longs;es betwixt <lb/>them) con&longs;i&longs;ts of many &longs;lender and flexi<lb/>ble Hairs; each of which, may indeed, <lb/>like a little Spring, be ea&longs;ily bent or roul<lb/>ed up; but will al&longs;o, like a Spring, be <lb/>&longs;till endeavouring to &longs;tretch it &longs;elf out <lb/>again. </s>

<s>For this (to omit other likene&longs;&longs;es betwixt <lb/>them) con&longs;i&longs;ts of many &longs;lender and flexi<lb/>ble Hairs; each of which, may indeed, <lb/>like a little Spring, be ea&longs;ily bent or roul<lb/>ed up; but will al&longs;o, like a Spring, be <lb/>&longs;till endeavouring to &longs;tretch it &longs;elf out <lb/>again. </s>

<s>For though both the&longs;e Haires, <lb/>and the Aerial Corpu&longs;cles to which we <lb/>liken them, do ea&longs;ily yield to externall <lb/>pre&longs;&longs;ures; yet each of them (by vertue of <lb/>its &longs;tructure) is endow'd with a Power or <lb/>Principle of &longs;elf-Dilatation; by vertue <lb/>whereof, though the hairs may by a Mans <lb/>hand be bent and crouded clo&longs;er together, <lb/>and into a narrower room then &longs;uits be&longs;t <lb/>with the nature of the Body: Yet whil'&longs;t <lb/>the compre&longs;&longs;ion la&longs;ts, there is in the fleece <lb/>they compo&longs;e an endeavour outwards, <lb/>whereby it continually thru&longs;ts again&longs;t the <lb/>hand that oppo&longs;es its Expan&longs;ion. </s>

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<s>There is yet another way to explicate <lb/>the Spring of the Air, namely, by &longs;uppo<lb/>&longs;ing with that mo&longs;t ingenious Gentleman, <lb/>Mon&longs;ieur <emph type="italics"/>Des Cartes,<emph.end type="italics"/> That the Air is no<lb/>thing but a Congeries or heap of &longs;mall <lb/>and (for the mo&longs;t part) of flexible Parti<lb/>cles; of &longs;everal &longs;izes, and of all kinde of Fi<lb/>gures which are rai&longs;'d by heat (e&longs;pecially <lb/>that of the Sun) into that fluid and <lb/>&longs;ubtle Etheriall Body that &longs;urrounds <lb/>the Earth; and by the re&longs;tle&longs;&longs;e agi<lb/>tation of that Cele&longs;tial Matter where<lb/>in tho&longs;e Particles &longs;wim, are &longs;o whirl'd <pb pagenum="25"/>round, that each Corpu&longs;cle endeavours <lb/>to beat off all others from coming within <lb/>the little Sphear requi&longs;ite to its motion <lb/>about its own Center; and (in ca&longs;e any, <lb/>by intruding into that Sphear &longs;hall op<lb/>po&longs;e its free Rotation) to expell or drive <lb/>it away: So that according to this Do<lb/>ctrine, it imports very little, whether the <lb/>particles of the Air have the &longs;tructure re<lb/>qui&longs;ite to Springs, or be of any other <lb/>form (how irregular &longs;oever) &longs;ince their <lb/>Ela&longs;tical power is not made to depend <lb/>upon their &longs;hape or &longs;tructure, but upon <lb/>the vehement agitation, and (as it were) <lb/>brandi&longs;hing motion, which they receive <lb/>from the fluid <emph type="italics"/>Ether<emph.end type="italics"/> that &longs;wiftly flows <lb/>between them, and whirling about each <lb/>of them (independently from the re&longs;t) <lb/>not onely keeps tho&longs;e &longs;lender Aërial <lb/>Bodies &longs;eparated and &longs;tretcht out (at lea&longs;t, <lb/>as far as the Neighbouring ones will per<lb/>mit) which otherwi&longs;e, by rea&longs;on of <lb/>their flexiblene&longs;s and weight, would <lb/>flag or curl; but al&longs;o makes them hit <lb/>again&longs;t, and knock away each other, and <lb/>con&longs;equently require more room, then <lb/>that which if they were compre&longs;&longs;'d, they <lb/>would take up. </s><pb pagenum="26"/>

<s>By the&longs;e two differing ways, my Lord, <lb/>may the Spring of the Air be explicated. <lb/>But though the former of them be that, <lb/>which by rea&longs;on of its &longs;eeming &longs;omewhat <lb/>more ea&longs;ie, I &longs;hall for the mo&longs;t part make <lb/>u&longs;e of in the following Di&longs;cour&longs;e: yet <lb/>am I not willing to declare peremptorily <lb/>for either of them, again&longs;t the other. </s>

<s>By the&longs;e two differing ways, my Lord, <lb/>may the Spring of the Air be explicated. <lb/></s>

<s>But though the former of them be that, <lb/>which by rea&longs;on of its &longs;eeming &longs;omewhat <lb/>more ea&longs;ie, I &longs;hall for the mo&longs;t part make <lb/>u&longs;e of in the following Di&longs;cour&longs;e: yet <lb/>am I not willing to declare peremptorily <lb/>for either of them, again&longs;t the other. </s>

<s>And <lb/>indeed, though I have in another Treati&longs;e <lb/>endeavoured to make it probable, that the <lb/>returning of Ela&longs;tical Bodies (if I may &longs;o <lb/>call them) forcibly bent, to their former <lb/>po&longs;ition, may be Mechanically explica<lb/>ted: Yet I mu&longs;t confe&longs;s, that to deter<lb/>mine whether the motion of Re&longs;titution <lb/>in Bodies, proceed from this, That the <lb/>parts of a Body of a peculiar Structure <lb/>are put into motion by the bending of the <lb/>&longs;pring, or from the endeavor of &longs;ome &longs;ub<lb/>tle ambient Body, who&longs;e pa&longs;&longs;age may be <lb/>oppo&longs;'d or ob&longs;tructed, or el&longs;e it's pre&longs;&longs;ure <lb/>unequally re&longs;i&longs;ted by rea&longs;on of the new <lb/>&longs;hape or magnitude, which the bending of <lb/>a Spring may give the Pores of it: To <lb/>determine this, I &longs;ay, &longs;eems to me a mat<lb/>ter of more difficulty, then at fir&longs;t &longs;ight <lb/>one would ea&longs;ily imagine it. </s>

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<s>And if it be yet further Objected a<lb/>gain&longs;t what hath been propo&longs;'d touching <lb/>the compactne&longs;s and pre&longs;&longs;ure of the Infe<lb/>rior Air; That we finde this very Air to <lb/>yield readily to the motion of little Flies, <lb/>and even to that of Feathers, and &longs;uch o<lb/>ther light and weak Bodies; which &longs;eems <lb/>to argue, that the particles of our Air are <lb/>not &longs;o compre&longs;&longs;'d as we have repre&longs;ented <lb/>them, e&longs;pecially, &longs;ince by our former <lb/>Experiment it appears, that the Air rea-<pb pagenum="34"/>dily dilated it &longs;elf downward, from the <lb/>Receiver into the Pump, when 'tis plain, <lb/>that it is not the incumbent Atmo&longs;phere, <lb/>but onely the &longs;ubjacent Air in the bra&longs;s <lb/>Cylinder that has been remov'd: If this, <lb/>I &longs;ay, be objected, we may reply, That <lb/>when a man &longs;queezes a Fleece of Wool in <lb/>his hand, he may feel that the Wool in<lb/>ce&longs;&longs;antly bears again&longs;t his hand, as that <lb/>which hinders the hairs it con&longs;i&longs;ts of, to <lb/>recover their former and more natural ex<lb/>tent. </s>

<s>So each parcel of the Air about the <lb/>Earth, does con&longs;tantly endeavour to thru&longs;t <lb/>away all tho&longs;e contiguous Bodies, whe<lb/>ther Aërial or more gro&longs;s, that keep <lb/>them bent, and hinder the expan&longs;ion of <lb/>its parts, which will dilate them&longs;elves or <lb/>flie abroad towards that part, whether up<lb/>wards or downwards, where they finde <lb/>their attempted Dilatation of them&longs;elves <lb/>le&longs;s re&longs;i&longs;ted by the neihgboring Bodies. <lb/>Thus the Corpu&longs;cles of that Air we have <lb/>been all this while &longs;peaking of, being un<lb/>able, by rea&longs;on of their weight, to a&longs;cend <lb/>above the Convexity of the Atmo&longs;phere, <lb/>and by rea&longs;on of the re&longs;i&longs;tance of the &longs;ur<lb/>face of the Earth and Water, to fall down <lb/>lower, they are forced, by their own gra<lb/>vity and this re&longs;i&longs;tance, to expand and <pb pagenum="35"/>diffu&longs;e them&longs;elves about the Terre&longs;tial <lb/>Globe; whereby it comes to pa&longs;s, that <lb/>they mu&longs;t as well pre&longs;s the contiguous <lb/>Corpu&longs;cles of Air that on either &longs;ide op<lb/>po&longs;e their Dilatation, as they mu&longs;t pre&longs;s <lb/>upon the &longs;urface of the Earth, and, as it <lb/>were recoyling thence, endeavor to thru&longs;t <lb/>away tho&longs;e upper particles of Air that <lb/>lean upon them. </s>

<s>Thus the Corpu&longs;cles of that Air we have <lb/>been all this while &longs;peaking of, being un<lb/>able, by rea&longs;on of their weight, to a&longs;cend <lb/>above the Convexity of the Atmo&longs;phere, <lb/>and by rea&longs;on of the re&longs;i&longs;tance of the &longs;ur<lb/>face of the Earth and Water, to fall down <lb/>lower, they are forced, by their own gra<lb/>vity and this re&longs;i&longs;tance, to expand and <pb pagenum="35"/>diffu&longs;e them&longs;elves about the Terre&longs;tial <lb/>Globe; whereby it comes to pa&longs;s, that <lb/>they mu&longs;t as well pre&longs;s the contiguous <lb/>Corpu&longs;cles of Air that on either &longs;ide op<lb/>po&longs;e their Dilatation, as they mu&longs;t pre&longs;s <lb/>upon the &longs;urface of the Earth, and, as it <lb/>were recoyling thence, endeavor to thru&longs;t <lb/>away tho&longs;e upper particles of Air that <lb/>lean upon them. </s>

<s>And as for the ea&longs;ie yielding of the Air <lb/>to the Bodies that move in it, if we con<lb/>&longs;ider that the Corpu&longs;cles whereof it con<lb/>&longs;i&longs;ts, though of a &longs;pringy nature, are yet <lb/>&longs;o very &longs;mall, as to make up (which 'tis <lb/>manife&longs;t they doe) a fluid Body, it will <lb/>not be difficult to conceive, that in the <lb/>Air, as in other Bodies that are fluid, the <lb/>little Bodies it con&longs;i&longs;ts of are in an almo&longs;t <lb/>re&longs;tle&longs;s motion, whereby they become <lb/>(as we have more fully di&longs;cour&longs;ed in ano<lb/><arrow.to.target n="marg3"></arrow.to.target><lb/>ther Treati&longs;e) very much di&longs;po&longs;ed to <lb/>yield to other Bodies, or ea&longs;ie to be di&longs;<lb/>plac'd by them, and that the &longs;ame Cor<lb/>pu&longs;cles are likewi&longs;e &longs;o variou&longs;ly mov'd, as <lb/>they are intire Corpu&longs;cles, that if &longs;ome <lb/>&longs;trive to pu&longs;h a Body plac'd among them <lb/>towards the right hand (for in&longs;tance) <lb/>others, who&longs;e motion has an oppo&longs;ite de<lb/>termination, as &longs;trongly thru&longs;t the &longs;ame <pb pagenum="36"/>Body towards the left; whereby neither <lb/>of them proves able to move it out of <lb/>its place, the pre&longs;&longs;ure on all hands being <lb/>reduced as it were to an <emph type="italics"/>Æquilibrium:<emph.end type="italics"/> &longs;o <lb/>that the Corpu&longs;cles of the Air mu&longs;t be as <lb/>well &longs;ometimes con&longs;idered under the no<lb/>tion of little Springs, which remaining <lb/>bent, are in their entire bulk tran&longs;ported <lb/>from place to place; as under the notion <lb/>of Springs di&longs;playing them&longs;elves, who&longs;e <lb/>parts flie abroad whil&longs;t as to their entire <lb/>bulk they &longs;carce change place: As the <lb/>two ends of a Bow, &longs;hot off, fly from one <lb/>another, whereas the Bow it &longs;elf may be <lb/>held fa&longs;t in the Archers hand; and that it <lb/>is the equal pre&longs;&longs;ure of the Air on all &longs;ides <lb/>upon the Bodies that are in it, which cau<lb/>&longs;es the ea&longs;ie Ce&longs;&longs;ion of its parts, may be <lb/>argu'd from hence: That if by the help <lb/>of our Engine the Air be but in great <lb/>part, though not totally drawn away <lb/>from one &longs;ide of a Body without being <lb/>drawn away from the other; he that &longs;hall <lb/>think to move that Body too and fro, as <lb/>ea&longs;ily as before, will finde him&longs;elf much <lb/>mi&longs;taken. </s>

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<s>And if it be ob<lb/>jected that this is unlikely, becau&longs;e ev'n <lb/>Gla&longs;s bubles, &longs;uch as are wont to be <lb/>blown at the flame of a Lamp, exceeding <lb/>thin and Hermetically &longs;eal'd will not <lb/>break; whereas it cannot be imagin'd <lb/>that &longs;o thin a Pri&longs;on of Gla&longs;s could re<lb/>&longs;i&longs;t the Ela&longs;tical force of all the included <lb/>Air, if that Air were &longs;o compre&longs;&longs;'d as we <lb/>&longs;uppo&longs;e. </s>

<s>It may be ea&longs;ily reply'd, That <lb/>the pre&longs;&longs;ure of the inward Air again&longs;t the <lb/>Gla&longs;s, is countervail'd by the equal pre&longs;-<pb pagenum="41"/>&longs;ure of the outward again&longs;t the &longs;ame Gla&longs;s. <lb/>And we &longs;ee in bubles, that by rea&longs;on of <lb/>this an exceeding thin film of Water is <lb/>often able, for a good while, to hinder the <lb/>eruption of a pretty quantity of Air. </s>

<s>And we &longs;ee in bubles, that by rea&longs;on of <lb/>this an exceeding thin film of Water is <lb/>often able, for a good while, to hinder the <lb/>eruption of a pretty quantity of Air. </s>

<s>And <lb/>this may be al&longs;o more con&longs;picuous in <lb/>tho&longs;e great Spherical bubles that boyes <lb/>&longs;ometimes blow with Water, to which <lb/>Sope has given a Tenacity. </s>

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<s>Hence <lb/>we need not wonder, that though the <pb pagenum="43"/>Sucker move ea&longs;ily enough up and down <lb/>in the Cylinder by the help of the <emph type="italics"/>Manu<lb/>brium;<emph.end type="italics"/> yet if the <emph type="italics"/>Manubrium<emph.end type="italics"/> be taken off, <lb/>it will require & con&longs;iderable &longs;trength to <lb/>move it either way. </s>

<s>Nor will it &longs;eem <lb/>&longs;trange, that if, when the Valve and <lb/>Stop-cock are well &longs;hut, you draw down <lb/>the Sucker, and then let go the <emph type="italics"/>Manubri<lb/>um;<emph.end type="italics"/> the Sucker will, as it were of it &longs;elf, <lb/>re-a&longs;cend to the top of the Cylinder, &longs;ince <lb/>the &longs;pring of the external Air findes no<lb/>thing to re&longs;i&longs;t its pre&longs;&longs;ing up the Sucker. <lb/>And for the &longs;ame rea&longs;on, when the Re<lb/>ceiver is almo&longs;t evacuated, though, ha<lb/>ving drawn down the Sucker, you open <lb/>the way from the Receiver to the Cylin<lb/>der, and then intercept that way again by <lb/>returning the Key; the Sucker will, up<lb/>on the letting go the <emph type="italics"/>Manubrium,<emph.end type="italics"/> be <lb/>forcibly carried up almo&longs;t to the top of <lb/>the Cylinder: Becau&longs;e the Air within the <lb/>Cylinder, being equally dilated and weak<lb/>ned with that of the Gla&longs;s, is unable to <lb/>with&longs;tand the pre&longs;&longs;ure of the external Air, <lb/>till it be driven into &longs;o little &longs;pace, that <lb/>there is an <emph type="italics"/>Æquilibrium<emph.end type="italics"/> betwixt its force <lb/>and that of the Air without. </s>

<s>And con<lb/>gruou&longs;ly hereunto we finde, that in this <lb/>ca&longs;e, the Sucker is drawn down with little <pb pagenum="44"/>le&longs;s difficulty, then if the Cylinder, be<lb/>ing devoid of Air, the Stop-cock were <lb/>exactly &longs;hut: We might take notice of <lb/>&longs;ome other things, that depend upon the <lb/>Fabrick of our Engine it &longs;elf; but to &longs;hun <lb/>prolixity, we will, in this place, content <lb/>our &longs;elves to mention one of them, which <lb/>&longs;eems to be of greater moment then the <lb/>re&longs;t, and it is this; that when the Sucker <lb/>has been impell'd to the top of the Cylin<lb/>der, and the Valve is &longs;o carefully &longs;topp'd, <lb/>that there is no Air left in the Cylinder a<lb/>bove the Sucker: If then the Sucker be <lb/>drawn to the lower part of the Cylinder, <lb/>he that manages the Pump findes not any <lb/>&longs;en&longs;ibly greater difficulty to depre&longs;s the <lb/>Sucker, when it is nearer the bottom of the <lb/>Cylinder, then when it is much further off. <lb/>Which circum&longs;tance we therefore think fit <lb/>to take notice of, becau&longs;e an eminent Mo<lb/>dern Naturali&longs;t hath taught, that, when the <lb/>Air is &longs;ucked out of a Body, the violence <lb/>wherewith it is wont to ru&longs;h into it again, <lb/>as &longs;oon as it is allow'd to re-enter, pro<lb/>ceeds mainly from this; That the pre&longs;&longs;ure <lb/>of the ambient Air is &longs;trengthned upon <lb/>the acce&longs;&longs;ion of the Air &longs;uck'd out; which, <lb/>to make it &longs;elf room, forces the neighbor<lb/>ing Air to a violent-&longs;ubingre&longs;&longs;ion o&longs; its <lb/>parts: which, i&longs; it were true, he that draws <pb pagenum="45"/>down the Sucker, would finde the re&longs;i&longs;t<lb/>ance of the external Air increa&longs;'d as he <lb/>draws it lower, more of the di&longs;placed Air <lb/>being thru&longs;t into it to compre&longs;s it. </s>

<s>And for the &longs;ame rea&longs;on, when the Re<lb/>ceiver is almo&longs;t evacuated, though, ha<lb/>ving drawn down the Sucker, you open <lb/>the way from the Receiver to the Cylin<lb/>der, and then intercept that way again by <lb/>returning the Key; the Sucker will, up<lb/>on the letting go the <emph type="italics"/>Manubrium,<emph.end type="italics"/> be <lb/>forcibly carried up almo&longs;t to the top of <lb/>the Cylinder: Becau&longs;e the Air within the <lb/>Cylinder, being equally dilated and weak<lb/>ned with that of the Gla&longs;s, is unable to <lb/>with&longs;tand the pre&longs;&longs;ure of the external Air, <lb/>till it be driven into &longs;o little &longs;pace, that <lb/>there is an <emph type="italics"/>Æquilibrium<emph.end type="italics"/> betwixt its force <lb/>and that of the Air without. </s>

<s>Which circum&longs;tance we therefore think fit <lb/>to take notice of, becau&longs;e an eminent Mo<lb/>dern Naturali&longs;t hath taught, that, when the <lb/>Air is &longs;ucked out of a Body, the violence <lb/>wherewith it is wont to ru&longs;h into it again, <lb/>as &longs;oon as it is allow'd to re-enter, pro<lb/>ceeds mainly from this; That the pre&longs;&longs;ure <lb/>of the ambient Air is &longs;trengthned upon <lb/>the acce&longs;&longs;ion of the Air &longs;uck'd out; which, <lb/>to make it &longs;elf room, forces the neighbor<lb/>ing Air to a violent-&longs;ubingre&longs;&longs;ion o&longs; its <lb/>parts: which, i&longs; it were true, he that draws <pb pagenum="45"/>down the Sucker, would finde the re&longs;i&longs;t<lb/>ance of the external Air increa&longs;'d as he <lb/>draws it lower, more of the di&longs;placed Air <lb/>being thru&longs;t into it to compre&longs;s it. </s>

<s>But, by <lb/>what has been di&longs;cour&longs;'d upon the fir&longs;t <lb/>Experiment, it &longs;eems more probable, that <lb/>without any &longs;uch &longs;trengthning of the pre&longs;<lb/>&longs;ure of the outward Air, the taking quite <lb/>away or the debilitating of the re&longs;i&longs;tance <lb/>from within, may &longs;uffice to produce the <lb/>effects under con&longs;ideration. </s>

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<s>By this means, af<lb/>ter a tryal or two, we were inabled to con<lb/>vey to the top of the Gla&longs;s a bubble of <lb/>Air equal enough, as to &longs;ight, to one <lb/>of tho&longs;e Divi&longs;ions: Then the open end <lb/>of the Tube being put into a &longs;mall Viol, <lb/>who&longs;e bottom was cover'd with Water <lb/>about half an Inch high; we included <lb/>both Gla&longs;&longs;es into a &longs;mall and &longs;lender Re<lb/>ceiver, and cau&longs;ed the Pump to be &longs;et a<lb/>work. </s>

<s>The event was, That at the fir&longs;t <lb/>ex&longs;uction of the Air there appear'd not <lb/>any expan&longs;ion of the bubble, comparable <lb/>to what appear'd at the &longs;econd, and that <lb/>upon a very few ex&longs;uctions the bubble <pb pagenum="57"/>reaching as low as the &longs;urface of the &longs;ub<lb/>jacent Water, gave us cau&longs;e to think <lb/>that if our Pipe had not been broken it <lb/>would have expanded it &longs;elf much fur<lb/>ther: Wherefore we took out the little <lb/>Tube, and found that be&longs;ides the twenty <lb/>&longs;ix divi&longs;ions formerly mention'd, the <lb/>Gla&longs;s bubble and &longs;ome part of the Pipe <lb/>to which the divided Parchment did not <lb/>reach, amounted to &longs;ix divi&longs;ions more. <lb/>Whereby it appears that the air had taken <lb/>up one and thirty times as much room as <lb/>before, and yet &longs;eem'd capable of a much <lb/>greater expan&longs;ion, if the Gla&longs;s would <lb/>have permitted it. </s>

<s>Whereby it appears that the air had taken <lb/>up one and thirty times as much room as <lb/>before, and yet &longs;eem'd capable of a much <lb/>greater expan&longs;ion, if the Gla&longs;s would <lb/>have permitted it. </s>

<s>Wherefore, after the <lb/>former manner, we let in another bubble, <lb/>that by our gue&longs;s was but half as big as <lb/>the former, and found, that upon the ex<lb/>&longs;uction of the Air from the Receiver, this <lb/>little bubble did not onely fill up the <lb/>whole Tube, but (in part) break through <lb/>the &longs;ubjacent Water in the Viol, and <lb/>thereby manife&longs;t it &longs;elf to have po&longs;&longs;e&longs;&longs;ed <lb/>&longs;ixty and odde times its former room. </s>

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<s>I know not whether it <lb/>be requi&longs;ite to take notice, that this Ex<lb/>periment was made indeed in a moi&longs;t <lb/>Night, but in a Room, in who&longs;e Chim<lb/>ney there was burning a good Fire, which <lb/>did perhaps &longs;omewhat rarifie the Air of <lb/>which the bubble con&longs;i&longs;ted. </s>

<s>It has &longs;eem'd almo&longs;t incredible which is <lb/>related by the Indu&longs;trious <emph type="italics"/>Mer&longs;ennus,<emph.end type="italics"/> That <lb/>the Air by the violence of heat, though <lb/>as great as our Ve&longs;&longs;els can &longs;upport with<lb/>out fu&longs;ion, can be &longs;o dilated as to take up <lb/>&longs;eventy times as much room as before: <lb/>Wherefore becau&longs;e we were willing to <lb/>have a confirmation of &longs;o &longs;trange a <emph type="italics"/>Phæno<lb/>menon;<emph.end type="italics"/> we once more convey'd into the <lb/>Tube a bubble of the bigne&longs;s of the for<lb/>mer, and pro&longs;ecuting the Experiment as <lb/>before with the &longs;ame Water, we ob&longs;erved <lb/>that the Air did manife&longs;tly &longs;tretch it &longs;elf <lb/>&longs;o far, as to appear &longs;everal times a good <lb/>way below the &longs;urface of the Water in the <lb/>Viol, and that too with a &longs;urface very <lb/>convex toward the bottom of the Pipe. <lb/>Nay, the Pump being ply'd a little lon<lb/>ger, the Air did manife&longs;tly reach to that <lb/>place where the bottom of the Tube <lb/>lean'd upon the bottom of the Viol, and <pb pagenum="61"/>&longs;eem'd to knock upon it and rebound <lb/>from it: Which Circum&longs;tances we adde, <lb/>partly that the <emph type="italics"/>Phænomenon<emph.end type="italics"/> we have been <lb/>relating may not be imputed to the <lb/>bare &longs;ub&longs;iding of the Water that fill'd <lb/>the Tube, upon the taking off the pre&longs;<lb/>&longs;ure of the ambient Air. </s>

<s>Nay, the Pump being ply'd a little lon<lb/>ger, the Air did manife&longs;tly reach to that <lb/>place where the bottom of the Tube <lb/>lean'd upon the bottom of the Viol, and <pb pagenum="61"/>&longs;eem'd to knock upon it and rebound <lb/>from it: Which Circum&longs;tances we adde, <lb/>partly that the <emph type="italics"/>Phænomenon<emph.end type="italics"/> we have been <lb/>relating may not be imputed to the <lb/>bare &longs;ub&longs;iding of the Water that fill'd <lb/>the Tube, upon the taking off the pre&longs;<lb/>&longs;ure of the ambient Air. </s>

<s>And partly al<lb/>&longs;o that it may appear that if our Expe<lb/>riments have not been as accurately made <lb/>as with fitter In&longs;truments might perhaps <lb/>be po&longs;&longs;ible; yet the expan&longs;ion of the <lb/>Air is likely to be rather greater then <lb/>le&longs;&longs;er then we have made it: Since the <lb/>Air was able to pre&longs;s away the Water at <lb/>the bottom of the Pipe, though that were <lb/>about two Inches below the &longs;urface of the <lb/>Water that was then in the Viol, and <lb/>would have been at lea&longs;t as high in the <lb/>Pipe, if the Water had onely &longs;ub&longs;ided and <lb/>not been depre&longs;&longs;ed: So that it &longs;eems not <lb/>unlikely that if the Experiment could be <lb/>&longs;o made, as that the expan&longs;ion of the Air <lb/>might not be re&longs;i&longs;ted by the Neighboring <lb/>Bodies, it would yet inlarge its bounds, <lb/>and perhaps &longs;tretch it &longs;elf to two hundred <lb/>times its former bulk, if not more. </s>

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<s>But be<lb/>ing made circum&longs;pect by the foregoing <lb/>mi&longs;chance, we had put the violl into a <lb/>Bladder, before we put it into the Re<lb/>ceiver to hinder this la&longs;t named Gla&longs;&longs;e <lb/>from being endanger'd by the breaking <lb/>of the other. </s>

<s>Then the Pneumaticall <lb/>ve&longs;&longs;ell being clos'd &longs;o that no way was <lb/>left for the outward Air to get into it, <lb/>but by breaking through the Viol, into <lb/>who&longs;e cavity it had free acce&longs;&longs;e by the <lb/>mouth of it, (which was purpo&longs;ely left <lb/>open,) the Sucker being nimbly drawn <lb/>down, the external Air immediatly pre&longs;&longs;'d <lb/>forcibly as well upon the Leaden-Co<lb/>ver as the Violl; and the Cover hap<lb/>pening to be in one place a little narrow<lb/>er then the edge of the Pneumatical Gla&longs;s, <lb/>was depre&longs;&longs;'d, and thru&longs;t into it &longs;o vio-<pb pagenum="69"/>lently by the incumbent Air, that get<lb/>ting a little within the tapering Lip of the <lb/>Gla&longs;s, it did like a kinde of Wedge, thru&longs;t <lb/>out that &longs;ide where it was depre&longs;&longs;'d, &longs;o as, <lb/>though the Receiver was new, to &longs;plit it. <lb/>This accident being thus mention'd upon <lb/>the by to confirm what we formerly &longs;aid <lb/>touching the fitne&longs;s or unfitne&longs;s of Gla&longs;&longs;es <lb/>of &longs;ome Figures to re&longs;i&longs;t the pre&longs;&longs;ure of <lb/>the Atmo&longs;phere; We will proceed to <lb/>relate the remaining part of the Experi<lb/>ment, namely, That having fitted on a <lb/>wider Cover to the &longs;ame Receiver, and <lb/>clo&longs;ed both that and the crack with Ce<lb/>ment, we pro&longs;ecuted the Experiment in <lb/>the manner above related, with this &longs;uc<lb/>ce&longs;s: That upon the quick depre&longs;&longs;ing of <lb/>the Sucker, the external Air bur&longs;t the <lb/>Body of the Viol in above a hundred pie<lb/>ces, many of them exceeding &longs;mall, and <lb/>that with &longs;uch violence that we found a <lb/>wide rent, be&longs;ides many holes, made in <lb/>the Bladder it &longs;elf. </s>

<s>This accident being thus mention'd upon <lb/>the by to confirm what we formerly &longs;aid <lb/>touching the fitne&longs;s or unfitne&longs;s of Gla&longs;&longs;es <lb/>of &longs;ome Figures to re&longs;i&longs;t the pre&longs;&longs;ure of <lb/>the Atmo&longs;phere; We will proceed to <lb/>relate the remaining part of the Experi<lb/>ment, namely, That having fitted on a <lb/>wider Cover to the &longs;ame Receiver, and <lb/>clo&longs;ed both that and the crack with Ce<lb/>ment, we pro&longs;ecuted the Experiment in <lb/>the manner above related, with this &longs;uc<lb/>ce&longs;s: That upon the quick depre&longs;&longs;ing of <lb/>the Sucker, the external Air bur&longs;t the <lb/>Body of the Viol in above a hundred pie<lb/>ces, many of them exceeding &longs;mall, and <lb/>that with &longs;uch violence that we found a <lb/>wide rent, be&longs;ides many holes, made in <lb/>the Bladder it &longs;elf. </s>

<s>And to evince that the&longs;e <emph type="italics"/>Phænomena<emph.end type="italics"/><lb/>were the effects of a limited and even <lb/>moderate force, and not of &longs;uch an ab<lb/>horrency of a <emph type="italics"/>Vacuum<emph.end type="italics"/> as that to avoid it, <lb/>many have been plea&longs;ed to think that Na<lb/>ture mu&longs;t, upon occa&longs;ion, exerci&longs;e an al-<pb pagenum="70"/>mo&longs;t boundle&longs;s power; we afterwards pur<lb/>po&longs;ely try'd this Experiment with &longs;everal <lb/>Gla&longs;&longs;es &longs;omewhat thicker then tho&longs;e Vi<lb/>ols, and found the event to verifie our con<lb/>jecture, that it would not &longs;ucceed: for <lb/>the Gla&longs;&longs;es were taken out as intire as they <lb/>were put in. </s>

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<s>And the la&longs;t, that we &longs;hould <lb/>be able to draw and keep out the Air much <lb/>more perfectly from &longs;uch &longs;mall Ve&longs;&longs;els <lb/>then from our large Receiver. </s>

<s>But though <lb/>we were not much di&longs;-appointed in the <lb/>expectation of the three fir&longs;t advantages, <lb/>yet we were in our hopes of the fourth. <lb/>For be&longs;ides the great difficulty we found <lb/>in fitting together the Gla&longs;&longs;es, the Stop<lb/>cocks and the Covers; be&longs;ides this I &longs;ay, <lb/>we found our &longs;elves &longs;eldom able to draw, <lb/>and keep out the Air &longs;o far as to make the <lb/>remaining Air in the&longs;e Receivers weaker <lb/>then the remaining Air in our great Recei<lb/>ver. </s>

<s>But though <lb/>we were not much di&longs;-appointed in the <lb/>expectation of the three fir&longs;t advantages, <lb/>yet we were in our hopes of the fourth. <lb/></s>

<s>For be&longs;ides the great difficulty we found <lb/>in fitting together the Gla&longs;&longs;es, the Stop<lb/>cocks and the Covers; be&longs;ides this I &longs;ay, <lb/>we found our &longs;elves &longs;eldom able to draw, <lb/>and keep out the Air &longs;o far as to make the <lb/>remaining Air in the&longs;e Receivers weaker <lb/>then the remaining Air in our great Recei<lb/>ver. </s>

<s>For though &longs;ometimes the Leaks <lb/>of &longs;ome of the&longs;e little Receivers may be <lb/>much either fewer or &longs;maller then tho&longs;e <lb/>of the larger Ve&longs;&longs;el; yet a little Air get-<pb pagenum="72"/>ting into one of the&longs;e, wherein it had but <lb/>little room to expand and di&longs;play it &longs;elf, <lb/>might pre&longs;s as much upon all parts of the <lb/>internal &longs;urface of the Ve&longs;&longs;el, and upon <lb/>the included Bodies, as a greater quan<lb/>tity of Air in a Ve&longs;&longs;el in who&longs;e capacity <lb/>it might finde more room to expand it <lb/>&longs;elf. </s>

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<s>Being de&longs;irous al&longs;o to try whether <lb/>there would be any difference as well in <lb/>our Receiver as there is wont to be el&longs;e<lb/>where betwixt Candles made of Wax and <lb/>tho&longs;e made of Tallow, as to their dura<lb/>tion; we took &longs;lender Tapers of white <lb/>Wax, (commonly called Virgins Wax) <lb/>that being found to burn with much le&longs;s <lb/>&longs;moke then common yellow Wax: Six <lb/>of the&longs;e of like bigne&longs;s, and each of them <lb/>of about the thickne&longs;s of a Swans Quill, <lb/>we pre&longs;&longs;'d together into one Candle: And <lb/>having lighted all the Weeks, we let in <lb/>the above-mention'd Wax into the Re<lb/>ceiver, and made what ha&longs;te we could to <lb/>clo&longs;e it up with Cement. </s>

<s>But though in <lb/>the mean while we left open the Valve <pb pagenum="77"/>of the Cylinder, the hole of the Stop<lb/>cock and that in the Cover of the Re<lb/>ceiver, that &longs;ome Air might get in to <lb/>cheri&longs;h the Flame and the &longs;moke might <lb/>have a vent; Yet for &longs;o great a Flame <lb/>the Air &longs;ufficed not &longs;o much as till the <lb/>Cover could be perfectly luted on: So <lb/>that before we were quite ready to imploy <lb/>the Pump, the Candle was extingui&longs;hed. <lb/>Wherefore we took but one of the a<lb/>bove mention'd Tapers, and having <lb/>lighted it, clo&longs;'d it up in the Receiver, to <lb/>try how long a &longs;mall Flame with a pro<lb/>portionable &longs;moke would continue in <lb/>&longs;uch a quantity of Air: But we found <lb/>upon two &longs;everal tryals, that from the <lb/>beginning of pumping, the Flame went <lb/>out in about a minute of an hour. </s>

<s>Wherefore we took but one of the a<lb/>bove mention'd Tapers, and having <lb/>lighted it, clo&longs;'d it up in the Receiver, to <lb/>try how long a &longs;mall Flame with a pro<lb/>portionable &longs;moke would continue in <lb/>&longs;uch a quantity of Air: But we found <lb/>upon two &longs;everal tryals, that from the <lb/>beginning of pumping, the Flame went <lb/>out in about a minute of an hour. </s>

<s>It <lb/>appear'd indeed to us that the &longs;winging <lb/>of the Wier to and fro (in the Engine <lb/>&longs;haken by pumping) ha&longs;ten'd the vani&longs;h<lb/>ing of the Flame, which &longs;eem'd by that <lb/>motion to be ca&longs;t &longs;ometimes on one &longs;ide <lb/>of the Week and &longs;ometimes on the o<lb/>ther; But though once we purpo&longs;ely <lb/>refrain'd pumping after a very few ex<lb/>&longs;uctions of the Air, that the Flame might <lb/>not be agitated, yet it la&longs;ted not much <lb/>longer then the newly mention'd time. <pb pagenum="78"/>And la&longs;tly, clo&longs;ing up the &longs;ame Taper, <lb/>lighted again, to di&longs;cover how long it <lb/>would la&longs;t without drawing out of the <lb/>Air, we found that it burn'd for a while <lb/>vividly enough, but afterwards began to <lb/>be le&longs;&longs;en'd more and more in all its Di<lb/>men&longs;ions. </s>

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<s>And we found that the Fire began to <lb/>go out fir&longs;t at the top and out-&longs;ides of the <lb/>Coals; but inwards and near the bottom <lb/>the Fire continu'd vi&longs;ible for above half <lb/>an hour, a great part of the Coals, e&longs;pe<lb/>cially tho&longs;e next the bottom, being burnt <lb/>to a&longs;hes before the Fire went out. </s>

<s>We cau&longs;'d likewi&longs;e a piece of Iron to <lb/>be forg'd, of the bigne&longs;s of a middle &longs;iz'd <lb/>Char-coal, and having made it red hot <pb pagenum="81"/>throughout; we cau&longs;'d it in the lately <lb/>mention'd Wier, to be &longs;peedily convey'd <lb/>and &longs;hut up into the Receiver, being de<lb/>&longs;irous to try what would become of a <lb/>glowing Body, by rea&longs;on of its texture <lb/>more vehemently hot then a burning <lb/>Coal of the &longs;ame bigne&longs;s, & yet unlike to <lb/>&longs;end forth &longs;uch copious & &longs;tifling Fumes: <lb/>But we could not ob&longs;erve any manife&longs;t <lb/>change upon the ex&longs;uction of the Air. <lb/>The Iron began indeed to lo&longs;e its Fiery <lb/>redne&longs;s at the top, but that &longs;eem'd to be <lb/>becau&longs;e it was it the upper end &longs;omewhat <lb/>more &longs;lender then at the lower: The red<lb/>ne&longs;s, though it were in the day time, con<lb/>tinued vi&longs;ible about four minutes; and <lb/>then, before it did quite di&longs;-appear, we <lb/>turn'd the Key of the Stop-cock but <lb/>could not di&longs;cern any change of the Iron <lb/>upon the ru&longs;hing in of the Air. </s>

<s>The Iron began indeed to lo&longs;e its Fiery <lb/>redne&longs;s at the top, but that &longs;eem'd to be <lb/>becau&longs;e it was it the upper end &longs;omewhat <lb/>more &longs;lender then at the lower: The red<lb/>ne&longs;s, though it were in the day time, con<lb/>tinued vi&longs;ible about four minutes; and <lb/>then, before it did quite di&longs;-appear, we <lb/>turn'd the Key of the Stop-cock but <lb/>could not di&longs;cern any change of the Iron <lb/>upon the ru&longs;hing in of the Air. </s>

<s>Yet &longs;ome <lb/>little remainders of Wax that &longs;tuck to <lb/>the Wier, and were turn'd into Fumes by <lb/>the heat of the neighboring Iron, &longs;eem'd <lb/>to afford a more plentiful, or at lea&longs;t a <lb/>much more free expanded &longs;moke when <lb/>the Air was &longs;uck'd out, then afterwards; <lb/>though allowance was made for the de<lb/>crea&longs;ing heat of the Iron. </s>

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<s>We wonld have made <lb/>more ob&longs;ervations concerning this Flame, <lb/>but that of two or three attempts we <lb/>afterwards made to repeat the kindling of <lb/>Powder, not any one &longs;ucceeded; and <lb/>we have not the lea&longs;ure to dwell long up<lb/>on one kinde of Tryals. </s>

<s>TO the&longs;e Experiments concerning Fire <lb/><arrow.to.target n="marg17"></arrow.to.target><lb/>we added another, which, though it &longs;uc<lb/>ceded not, may perhaps without imper<lb/>tinency be recorded: partly becau&longs;e that <lb/>(as we have in another Treati&longs;e amply de<lb/>clar'd) it is u&longs;efull to recite what Experi<lb/>ments mi&longs;carry as well as what &longs;ucceed. <lb/>And partly al&longs;o becau&longs;e it is very po&longs;&longs;ible <lb/>that what we endeavored in vaine, may be <lb/>performed by Your Lord&longs;hip, or &longs;ome <lb/>other <emph type="italics"/>Virtuo&longs;o<emph.end type="italics"/> that &longs;hall have &longs;lancker <lb/>Ve&longs;&longs;ells then we had, and more Sunny <lb/>dayes then the pre&longs;ent Winter allows <lb/>us. </s>

<s>And partly al&longs;o becau&longs;e it is very po&longs;&longs;ible <lb/>that what we endeavored in vaine, may be <lb/>performed by Your Lord&longs;hip, or &longs;ome <lb/>other <emph type="italics"/>Virtuo&longs;o<emph.end type="italics"/> that &longs;hall have &longs;lancker <lb/>Ve&longs;&longs;ells then we had, and more Sunny <lb/>dayes then the pre&longs;ent Winter allows <lb/>us. </s>

<s><margin.target id="marg17"></margin.target><emph type="italics"/>Experi<lb/>ment<emph.end type="italics"/> 15.</s>

<s>We convey'd then into one of our &longs;mall <lb/>Receivers a piece of matter combu&longs;tible, <lb/>dry and black (experience declaring things <pb pagenum="103"/>of that colour to be mo&longs;t ea&longs;ily kindled) <lb/>& carefully clo&longs;ing the Ve&longs;&longs;el we brought <lb/>it to a Window at which the Sun, not very <lb/>faire from the Meridian, &longs;hone in very free<lb/>ly: then drawing out the Aire with &longs;peed <lb/>united the Sun-beames with a burning <lb/>Gla&longs;s upon the combu&longs;tible matter which <lb/>began immediatly to &longs;end forth a Smoke <lb/>that quickly darkned the Receiver, but <lb/>notwith&longs;tanding all our care and diligence <lb/>the externall Aire got in &longs;o fa&longs;t that after <lb/>diver&longs;e tryals we were fayne to leave off <lb/>the Experiment in that Gla&longs;&longs;e and induc'd <lb/>to make tryall of it in our great Re<lb/>ceiver. </s>

<s>Haveing then after &longs;ome difficulty <lb/>lodg'd the combu&longs;tible matter in the ca<lb/>vity of this Ve&longs;&longs;ell in &longs;uch manner as that <lb/>it was almo&longs;t contiguous to that &longs;ide <lb/>thereof that was next the Sun, we did en<lb/>deavor with a pretty large burning Gla&longs;s <lb/>to kindle it, but found, as we fear'd, <lb/>That by rea&longs;on of the thickne&longs;s of the <lb/>Gla&longs;s, (which was al&longs;o of a le&longs;s pure and <lb/>le&longs;s Diaphanous matter then the o<lb/>ther) the Sun-beams thrown in by the <lb/>burning Gla&longs;s, were in their pa&longs;&longs;age <lb/>&longs;o Di&longs;located and Scattered (not now to <lb/>mention tho&longs;e many that being reflected, <pb pagenum="104"/>I could not pierce into the cavity of the <lb/>Receiver) that we could not po&longs;&longs;ibly u<lb/>nite enough of them to kindle the matter, <lb/>nor &longs;o much as to make it &longs;en&longs;ibly &longs;moke. <lb/>Yet we hope that the &longs;eeing whether Bo<lb/>dies (other then Gun-powder) may be <lb/>kindled, and what would happen to them <lb/>when &longs;et on fire, in a place in great mea<lb/>&longs;ure devoid of Air, may prove &longs;o Lucife<lb/>rous an Experiment, that when the Sea<lb/>&longs;on is more favorable we &longs;hall, God per<lb/>mitting, make further tryal of it, and ac<lb/>quaint Your Lord&longs;hip with the Event, if <lb/>it prove pro&longs;perous. </s>

<s>Yet we hope that the &longs;eeing whether Bo<lb/>dies (other then Gun-powder) may be <lb/>kindled, and what would happen to them <lb/>when &longs;et on fire, in a place in great mea<lb/>&longs;ure devoid of Air, may prove &longs;o Lucife<lb/>rous an Experiment, that when the Sea<lb/>&longs;on is more favorable we &longs;hall, God per<lb/>mitting, make further tryal of it, and ac<lb/>quaint Your Lord&longs;hip with the Event, if <lb/>it prove pro&longs;perous. </s>

<s>In the mean time <lb/>we &longs;hall pa&longs;s on to other Experiments, <lb/>a&longs;&longs;oon as we have adverti&longs;'d Your Lord<lb/>&longs;hip that we have forborn to make &longs;uch <lb/>Reflections upon the &longs;everal Experiments <lb/>we have &longs;et down concerning Fire, as the <lb/>matter would have ea&longs;ily enough afford<lb/>ed, and Your Lord&longs;hip may perhaps have <lb/>expected. </s>

<s>But I made the le&longs;s &longs;cruple to <lb/>forbear the annexing of Speculations to <lb/>the&longs;e Recitals, becau&longs;e <emph type="italics"/>Carneades<emph.end type="italics"/> & <emph type="italics"/>Eleu<lb/>therius<emph.end type="italics"/> have in &longs;ome Dialogues concern<lb/>ing Heat and Flame, which were la&longs;t year <lb/>&longs;een by &longs;ome Friends, and may be, when <lb/>you plea&longs;e, commanded by You, men-<pb pagenum="105"/>tion'd divers of my Thoughts and Expe<lb/>riments concerning Fire. </s>

<s>WE de&longs;igned to try whether or no <lb/><arrow.to.target n="marg18"></arrow.to.target><lb/>divers Magnetical Experiments <lb/>would exhibit any unu&longs;ual <emph type="italics"/>Phænomena,<emph.end type="italics"/><lb/>being made in our Evacuated Receiver <lb/>in&longs;tead of the open Air: But for want of <lb/>lei&longs;ure and conveniency to pro&longs;ecute &longs;uch <lb/>Tryals, we were induced to re&longs;erve the <lb/>re&longs;t for an other time, and to content our <lb/>&longs;elves with making that which follows. <lb/>We convey'd into the Receiver a little <lb/>Pede&longs;tal of Wood, in the mid&longs;t of which <lb/>was perpendicularly erected a &longs;lender <lb/>Iron, upon who&longs;e &longs;harp point an excited <lb/>Needle of Steel purpo&longs;ely made, and of <lb/>about five Inches long, was &longs;o placed <lb/>that hanging in an <emph type="italics"/>Æquilibrium<emph.end type="italics"/> it could <lb/>move freely towards either hand. </s>

<s>We convey'd into the Receiver a little <lb/>Pede&longs;tal of Wood, in the mid&longs;t of which <lb/>was perpendicularly erected a &longs;lender <lb/>Iron, upon who&longs;e &longs;harp point an excited <lb/>Needle of Steel purpo&longs;ely made, and of <lb/>about five Inches long, was &longs;o placed <lb/>that hanging in an <emph type="italics"/>Æquilibrium<emph.end type="italics"/> it could <lb/>move freely towards either hand. </s>

<s>Then <lb/>the Air being after the u&longs;ual manner <lb/>pumped out, we apply'd a Load-&longs;tone <lb/>moderately vigorous to the out-&longs;ide of <lb/>of the Gla&longs;s, and found that it Attracted <lb/>or Repell'd the ends of the Needle, accor<lb/>ding to the Laws Magnetical, without <lb/>any remarkable difference from what the <lb/>&longs;ame Load-&longs;tone would have done had <pb pagenum="106"/>none of the Air been drawn away from a<lb/>bout the Needle, which when the Load<lb/>&longs;tone was removed, after &longs;ome tremu<lb/>lous Vibrations to and fro, re&longs;ted in a po<lb/>&longs;ition wherein it look'd North and <lb/>South. </s>

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<s>But on the other &longs;ide it may be &longs;aid, <pb pagenum="121"/>That as for the &longs;ubtle Matter which makes <lb/>the Objects enclo&longs;ed in our evacuated Re<lb/>ceiver, vi&longs;ible, and the Magnetical Efflu<lb/>via of the Earth that may be pre&longs;um'd to <lb/>pa&longs;s thorow it, though we &longs;hould grant <lb/>our Ve&longs;&longs;el not to be quite devoyd of <lb/>them, yet we cannot &longs;o rea&longs;onably affirm <lb/>it to be repleni&longs;h'd with them, as we may <lb/>&longs;uppo&longs;e, that if they were gather'd toge<lb/>ther into one place without Intervals be<lb/>tween them, they would fill but a &longs;mall <lb/>part of the whole Receiver. </s>

<s>As in the <lb/>thirteenth Experiment, a piece of Match <lb/>was incon&longs;iderable for its bulk, while&longs;t its <lb/>parts lay clo&longs;e together, that afterwards <lb/>(when the Fire had &longs;catter'd them into <lb/>&longs;moke) &longs;eem'd to repleni&longs;h all the Ve&longs;&longs;el. <lb/>For (as el&longs;ewhere our Experiments have <lb/>demon&longs;trated) both Light and the Efflu<lb/>via of the Load-&longs;tone, may be readily ad<lb/>mitted into a Gla&longs;s, Hermetically &longs;eal'd, <lb/>though before their Admi&longs;&longs;ion, as full of <lb/>Air as hollow Bodies here below are wont <lb/>to be, &longs;o that upon the ex&longs;uction of the <lb/>Air, the large &longs;pace de&longs;erted by it, may <lb/>remain empty, notwith&longs;tanding the pre<lb/>tence of tho&longs;e &longs;ubtle Corpu&longs;cles, by <lb/>which Lucid and Magnetical Bodies pro<lb/>duce their effects. </s><pb pagenum="122"/>

<s>For (as el&longs;ewhere our Experiments have <lb/>demon&longs;trated) both Light and the Efflu<lb/>via of the Load-&longs;tone, may be readily ad<lb/>mitted into a Gla&longs;s, Hermetically &longs;eal'd, <lb/>though before their Admi&longs;&longs;ion, as full of <lb/>Air as hollow Bodies here below are wont <lb/>to be, &longs;o that upon the ex&longs;uction of the <lb/>Air, the large &longs;pace de&longs;erted by it, may <lb/>remain empty, notwith&longs;tanding the pre<lb/>tence of tho&longs;e &longs;ubtle Corpu&longs;cles, by <lb/>which Lucid and Magnetical Bodies pro<lb/>duce their effects. </s><pb pagenum="122"/>

<s>And as for the Allegations above <lb/>mention'd, they &longs;eem to prove but that <lb/>the Receiver devoy'd of Air, <emph type="italics"/>May<emph.end type="italics"/> be re<lb/>pleni&longs;h'd with &longs;ome &longs;uch Etherial Matter, <lb/>as &longs;ome Modern Naturali&longs;ts write of; but <lb/>not that it really <emph type="italics"/>is<emph.end type="italics"/> &longs;o. </s>

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<s>For often times upon the opening <pb pagenum="125"/>of the inverted Tube into the Ve&longs;&longs;ell'd <lb/>Mercury, you may ob&longs;erve a bubble of <lb/>Air to a&longs;cend from the bottom of the <lb/>Tube through the &longs;ub&longs;iding Quick-&longs;ilver <lb/>to the top; and almo&longs;t always you may, <lb/>if you look narrowly, take notice of a <lb/>multitude of &longs;mall bubbles all along the <lb/>in&longs;ide of the Tube betwixt the Quick<lb/>&longs;ilver & the gla&longs;s: (not now to mention the <lb/>Particles of Air that lye conceal'd in the <lb/>very Body of the Mercury) Many of <lb/>which, upon the Quick-&longs;ilvers for&longs;aking <lb/>the upper part of the Tube, do break in<lb/>to that de&longs;erted &longs;pace where they finde <lb/>little or no re&longs;i&longs;tance to their expanding <lb/>of them&longs;elves. </s>

<s>Whether this be the rea<lb/>&longs;on that upon the Application of warm <lb/>Bodies to the emptyed part of the Tube, <lb/>the &longs;ubjacent Mercury would be depre&longs;&longs;'d <lb/>&longs;omewhat lower, we &longs;hall not determine; <lb/>though it &longs;eem very probable, e&longs;pecially <lb/>&longs;ince we found that upon the application <lb/>of Linnen cloaths dipped in Water, to <lb/>the &longs;ame part of the Tube, the Quick<lb/>&longs;ilver would &longs;omewhat a&longs;cend, as if the <lb/>cold had conden&longs;'d the Impri&longs;on'd Air, <lb/>that pre&longs;&longs;'d upon it, into a le&longs;&longs;er room. <lb/>But that the de&longs;erted &longs;pace is not wont to <lb/>be totally devoid of Air, we were induc'd <pb pagenum="126"/>to think by &longs;everal Circum&longs;tances. </s>

<s>But that the de&longs;erted &longs;pace is not wont to <lb/>be totally devoid of Air, we were induc'd <pb pagenum="126"/>to think by &longs;everal Circum&longs;tances. </s>

<s>For <lb/>when an eminent Mathematician, and ex<lb/>cellent Experimenter, had taken great <lb/>pains and &longs;pent much time in accuratly fil<lb/>ling up a Tube of Mercury, we found <lb/>that yet there remain'd &longs;tore of incon&longs;pi<lb/>cuous bubbles, by inverting the Tube, <lb/>letting the Quick-&longs;ilver fall to its wonted <lb/>heighth; and by approaching (by de<lb/>grees) a red hot Iron to the out-&longs;ide of the <lb/>Tube, over again&longs;t the upper part of the <lb/>Mercurial Cylinder, for hereby the little <lb/>unheeded bubbles, being mightily expan<lb/>ded, a&longs;cended in &longs;uch numbers, and &longs;o fa&longs;t <lb/>to the de&longs;erted &longs;pace, that the upper part <lb/>of the Quick-&longs;ilver &longs;eem'd, to our wonder, <lb/>to boyl. </s>

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<s>This we fill'd with Mer<lb/>cury, though not with as much care as we <lb/>could, yet with &longs;omewhat more then is <lb/>wont to be u&longs;ed in making the <emph type="italics"/>Torricellian<emph.end type="italics"/><lb/>Experiment. </s>

<s>Then, having according to <lb/>the manner inverted the Tube, and open'd <lb/>the mouth of it beneath the &longs;urface of <lb/>&longs;ome other Quick-&longs;ilver, that in the Tube <lb/>fell down to the wonted heigth, leaving, <pb pagenum="130"/>as is u&longs;ual, &longs;ome little Particles of Air in <lb/>the &longs;pace it de&longs;erted, as we ghe&longs;t by ob<lb/>&longs;erving, that upon the Application of hot <lb/>Bodies to the upper part of the Tube, the <lb/>Quick-&longs;ilver would be a little depre&longs;&longs;'d. <lb/>La&longs;tly, having put both the Tube and the <lb/>Ve&longs;&longs;el it lean'd on into a convenient <lb/>Wooden Frame, to keep them from mi&longs;<lb/>chances: we plac'd that Frame in a Win<lb/>dow within my Bed-chamber, that I might <lb/>both keep the Mercury from being &longs;tirr'd, <lb/>and have opportunity to watch from time <lb/>to time the <emph type="italics"/>Phænomena<emph.end type="italics"/> it was to exhibit. <lb/>For the better di&longs;covery of which, when <lb/>the Quick-&longs;ilver both in the Tube and <lb/>&longs;ubjacent Ve&longs;&longs;el was perfectly at re&longs;t, we <lb/>took notice, by a mark made on the out<lb/>&longs;ide of the Gla&longs;s, how high the included <lb/>Liquor then reach'd. </s>

<s>La&longs;tly, having put both the Tube and the <lb/>Ve&longs;&longs;el it lean'd on into a convenient <lb/>Wooden Frame, to keep them from mi&longs;<lb/>chances: we plac'd that Frame in a Win<lb/>dow within my Bed-chamber, that I might <lb/>both keep the Mercury from being &longs;tirr'd, <lb/>and have opportunity to watch from time <lb/>to time the <emph type="italics"/>Phænomena<emph.end type="italics"/> it was to exhibit. <lb/></s>

<s>For the better di&longs;covery of which, when <lb/>the Quick-&longs;ilver both in the Tube and <lb/>&longs;ubjacent Ve&longs;&longs;el was perfectly at re&longs;t, we <lb/>took notice, by a mark made on the out<lb/>&longs;ide of the Gla&longs;s, how high the included <lb/>Liquor then reach'd. </s>

<s><margin.target id="marg20"></margin.target><emph type="italics"/>Experi<lb/>ment<emph.end type="italics"/> 18.</s>

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<s>For the Experiment that occa&longs;ion'd <lb/>this Di&longs;cour&longs;e, &longs;eems to make it proba<lb/>ble enough that there may be &longs;trange <lb/>Ebbings and Flowings, as it were, in the <lb/>Atmo&longs;phere; or at lea&longs;t, that it may ad<lb/>mit great and &longs;udden Mutations, either as <lb/>to its Altitude or its Den&longs;ity, from cau&longs;es, <lb/>as well unknown to us, as the effects are <lb/>unheeded by us. </s>

<s>And that You may not <lb/>think that there is nothing in Nature but <lb/>our Experiment that agrees with this our <lb/>conjecture, we might put Your Lord&longs;hip <lb/>in minde of the Pains and Aches that are <lb/>often complain'd of by tho&longs;e that have <lb/>had great Wounds or Brui&longs;es, and that <lb/>doe pre&longs;age great Mutations in the Air <lb/>oftentimes, whil&longs;t to &longs;trong and healthy <lb/>Per&longs;ons no &longs;ign of any &longs;uch thing appears. <lb/>And that is al&longs;o very memorable to this <lb/>purpo&longs;e, which I remember I have &longs;ome<lb/>where read in a Book of the Ingenious <lb/><emph type="italics"/>Kircherus,<emph.end type="italics"/> who giving a pertinent admoni<lb/>tion concerning the various refractions <lb/>that may happen in the Air, relates, That <pb pagenum="137"/>during his &longs;tay in <emph type="italics"/>Malta,<emph.end type="italics"/> he often &longs;aw <lb/>Mount <emph type="italics"/>Ætna,<emph.end type="italics"/> though the next day, not<lb/>with&longs;tanding its being extreamly clear, he <lb/>could not &longs;ee it; adding, that <emph type="italics"/>Vintemillius,<emph.end type="italics"/><lb/>a very Learned Per&longs;on, did oftentimes, <lb/>from a Hill he names, behold the whole <lb/>I&longs;land he calls <emph type="italics"/>Luprica<emph.end type="italics"/> protuberant above <lb/>the Sea, though at other times, notwith<lb/>&longs;tanding a clear Sky, he could not &longs;ee it. <lb/>And though perhaps this may be in part a<lb/>&longs;cribed to the various light & po&longs;ition of <lb/>the &longs;un, or to the various di&longs;po&longs;ition of the <lb/>Spectators eye, or peradventure to &longs;ome <lb/>other cau&longs;e; yet the mo&longs;t probable cau&longs;e <lb/>&longs;eems to be the differing Den&longs;ity of the <lb/>Air, occa&longs;ion'd by Exhalations capable to <lb/>increa&longs;e the refraction, and con&longs;equently <lb/>bring Beams to the Eye, which otherwi&longs;e <lb/>would not fall on it. </s>

<s>And that is al&longs;o very memorable to this <lb/>purpo&longs;e, which I remember I have &longs;ome<lb/>where read in a Book of the Ingenious <lb/><emph type="italics"/>Kircherus,<emph.end type="italics"/> who giving a pertinent admoni<lb/>tion concerning the various refractions <lb/>that may happen in the Air, relates, That <pb pagenum="137"/>during his &longs;tay in <emph type="italics"/>Malta,<emph.end type="italics"/> he often &longs;aw <lb/>Mount <emph type="italics"/>Ætna,<emph.end type="italics"/> though the next day, not<lb/>with&longs;tanding its being extreamly clear, he <lb/>could not &longs;ee it; adding, that <emph type="italics"/>Vintemillius,<emph.end type="italics"/><lb/>a very Learned Per&longs;on, did oftentimes, <lb/>from a Hill he names, behold the whole <lb/>I&longs;land he calls <emph type="italics"/>Luprica<emph.end type="italics"/> protuberant above <lb/>the Sea, though at other times, notwith<lb/>&longs;tanding a clear Sky, he could not &longs;ee it. <lb/></s>

<s>And though perhaps this may be in part a<lb/>&longs;cribed to the various light & po&longs;ition of <lb/>the &longs;un, or to the various di&longs;po&longs;ition of the <lb/>Spectators eye, or peradventure to &longs;ome <lb/>other cau&longs;e; yet the mo&longs;t probable cau&longs;e <lb/>&longs;eems to be the differing Den&longs;ity of the <lb/>Air, occa&longs;ion'd by Exhalations capable to <lb/>increa&longs;e the refraction, and con&longs;equently <lb/>bring Beams to the Eye, which otherwi&longs;e <lb/>would not fall on it. </s>

<s>We have likewi&longs;e <lb/>in another Treati&longs;e mention'd our having <lb/>often ob&longs;erv'd with Tele&longs;copes a plenty <lb/>of Steams in the Air, which without &longs;uch <lb/>a help would not be taken notice of, and <lb/>which as they were not at all times to be <lb/>&longs;een even through a Tele&longs;cope, &longs;o they <lb/>did &longs;ometimes, e&longs;pecially after a &longs;hower of <lb/>Rain, ha&longs;tily di&longs;appear: and when we <lb/>have vi&longs;ited tho&longs;e places that abound with <lb/>Mines, we have &longs;everal times been told <pb pagenum="138"/>by the Diggers, that even when the Sky <lb/>&longs;eem'd clear, there would not &longs;eldom &longs;ud<lb/>denly ari&longs;e, and &longs;ometimes long continue, <lb/>a certain Steam (which they u&longs;ually call a <lb/>damp) &longs;o gro&longs;s and thick, that it would <lb/>oftentimes put out their very Candles, if <lb/>they did not &longs;ea&longs;onably prevent it. </s>

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<s>Nor does it appear in tho&longs;e Gla&longs;&longs;es, <lb/>which for Chymical Experiments we u&longs;u<lb/>ally clo&longs;e with <emph type="italics"/>Hermes<emph.end type="italics"/> his Seal (as they <lb/>call it) that the included Air does, during <lb/>its long Impri&longs;onment, notwith&longs;tanding <lb/>the alteration it receives from various de<lb/>grees of heat, di&longs;cernably alter its nature. <lb/>Whereas we plainly perceive in our Dige<lb/>&longs;tions and Di&longs;tillations, that though it <lb/>may be rarified into invi&longs;ible Vapors, yet <lb/>it is not really chang'd into Air, but onely <lb/>divided by heat, and &longs;catter'd into very <lb/>minute parts, which meeting together in <lb/>the Alembick or in the Receiver, do pre<lb/>&longs;ently return into &longs;uch Water as they con<lb/>&longs;tituted before. </s>

<s>Whereas we plainly perceive in our Dige<lb/>&longs;tions and Di&longs;tillations, that though it <lb/>may be rarified into invi&longs;ible Vapors, yet <lb/>it is not really chang'd into Air, but onely <lb/>divided by heat, and &longs;catter'd into very <lb/>minute parts, which meeting together in <lb/>the Alembick or in the Receiver, do pre<lb/>&longs;ently return into &longs;uch Water as they con<lb/>&longs;tituted before. </s>

<s>And we al&longs;o &longs;ee, that <lb/>ev'n Spirit of Wine, and other &longs;ubtle and <lb/>fugitive Spirits, though they ea&longs;ily fly in<lb/>to the Air, and mingle with it, do yet in <lb/>the Gla&longs;&longs;es of Chymi&longs;ts ea&longs;ily lay a&longs;ide <lb/>the di&longs;gui&longs;e of Air, and re&longs;ume the deve<lb/>&longs;ted form of Liquors. </s>

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<s>And I re<lb/><arrow.to.target n="marg27"></arrow.to.target><lb/>member too, that the accurate <emph type="italics"/>Varenius<emph.end type="italics"/><lb/>tells us, That in the I&longs;lands commonly <lb/>called <emph type="italics"/>Azores,<emph.end type="italics"/> the Air (and Wind) is &longs;o <lb/>&longs;harp, that in a &longs;hort time it frets not only <lb/>Iron Plates, but the very Tiles upon the <lb/>Roofs of Hou&longs;es, and reduces them to <lb/>du&longs;t. </s>

<s>And I have el&longs;ewhere mention'd <lb/>&longs;ome recent Ob&longs;ervations of this kinde. <lb/>But it may be &longs;aid, That the above-men<lb/>tion'd Authors a&longs;cribe the recited effects <lb/>chiefly to the Winds, and that however <lb/>the corro&longs;ion of the Iron and the Tiles <lb/>may proceed not from the Air it &longs;elf, or <lb/>any of its genuine parts, but from &longs;ome <pb pagenum="167"/>&longs;aline Corpu&longs;cles di&longs;per&longs;'d through the <lb/>Air, and driven by the Winds again&longs;t the <lb/>Bodies it is pre&longs;um'd to fret. </s>

<s>And I have el&longs;ewhere mention'd <lb/>&longs;ome recent Ob&longs;ervations of this kinde. <lb/></s>

<s>But it may be &longs;aid, That the above-men<lb/>tion'd Authors a&longs;cribe the recited effects <lb/>chiefly to the Winds, and that however <lb/>the corro&longs;ion of the Iron and the Tiles <lb/>may proceed not from the Air it &longs;elf, or <lb/>any of its genuine parts, but from &longs;ome <pb pagenum="167"/>&longs;aline Corpu&longs;cles di&longs;per&longs;'d through the <lb/>Air, and driven by the Winds again&longs;t the <lb/>Bodies it is pre&longs;um'd to fret. </s>

<s>And that <lb/>&longs;uch volatile Salts may copiou&longs;ly a&longs;cend <lb/>into the Air, and yet retain their Nature, <lb/>as doth the more fixt Salt in the Sea Wa<lb/>ter, the &longs;ublimations of <emph type="italics"/>Sal-Armoniack<emph.end type="italics"/><lb/>may &longs;ufficiently evince. </s>

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<s><emph type="italics"/>Debet autem cameræ illa &longs;ituari in loco <lb/>quantum fieri pote&longs;t &longs;icciori it a ut longo ca<lb/>nali aqua intr a eam derivetur ne locus hu<lb/>miditate &longs;ua Organis officiat.<emph.end type="italics"/></s>

<s>Thus far the Ingenious <emph type="italics"/>Kircherus,<emph.end type="italics"/> whom <lb/>I the rather cite, becau&longs;e although I have <lb/>been informed of divers Ventiducts (as <lb/>they call them) by very knowing Tra<lb/>vellers that have ob&longs;erv'd them: Yet this <lb/>relation of our Author being very pun<lb/>ctual, and deliver'd upon his own particu<lb/>lar Experience, has, I confe&longs;s, made me <lb/>wi&longs;h I had had the good fortune when I <lb/>was at <emph type="italics"/>Rome,<emph.end type="italics"/> to take notice of the&longs;e Or<lb/>gans; or that I had now the opportunity <lb/>of examining of &longs;uch an Experiment. <lb/>For if upon a &longs;trict inquiry I &longs;hould find <lb/>that the breath that blows the Organs <pb pagenum="174"/>does not really upon the cea&longs;ing of its un<lb/>u&longs;ual agitation by little and little relap&longs;e <lb/>into water, I &longs;hould &longs;trongly &longs;u&longs;pect that <lb/>'tis po&longs;&longs;ible for Water to be ea&longs;ily turn'd <lb/>into Air. </s>

<s>For if upon a &longs;trict inquiry I &longs;hould find <lb/>that the breath that blows the Organs <pb pagenum="174"/>does not really upon the cea&longs;ing of its un<lb/>u&longs;ual agitation by little and little relap&longs;e <lb/>into water, I &longs;hould &longs;trongly &longs;u&longs;pect that <lb/>'tis po&longs;&longs;ible for Water to be ea&longs;ily turn'd <lb/>into Air. </s>

<s>I remember indeed, that we <lb/>have formerly taught that there lurks an <lb/>inter&longs;per&longs;ed Air in the pores of ordinary <lb/>Water, which may po&longs;&longs;ibly be &longs;truck out <lb/>by the breaking of the Water in its fall <lb/>into the Æolian Chamber, (as he calls it.) <lb/>But in regard the Scheme &longs;eems to repre<lb/>&longs;ent that Chamber as clo&longs;ely &longs;hut, and <lb/>thereby forbids us to &longs;uppo&longs;e that any Air <lb/>is carried into it but what is latitant in the <lb/>Water, it will &longs;carce &longs;eem probable to <lb/>him who remembers how &longs;mall a propor<lb/>tion of Air, that appear'd to be when its <lb/>rarification &longs;ea&longs;ed, which was conceal'd in <lb/>the Water we freed from bubbles in our <lb/>Receiver, that &longs;o little Air as is common<lb/>ly di&longs;per&longs;'d through Water, &longs;hould be a<lb/>ble, in &longs;o little Water as was requi&longs;ite for <lb/>&longs;o &longs;mall a room, to make &longs;o vehement a <lb/>Wind as our Author here tells us of. </s>

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<s>The Air being &longs;paringly let into the <lb/>Receiver, the great bubbles formerly <lb/>mention'd as incumbent upon one ano<lb/>ther, in that Gla&longs;s that contain'd the Spi<lb/>rit of Urine, were by orderly degrees <lb/>le&longs;&longs;en'd, till at length they wholly &longs;ub&longs;i<lb/>ded, notwith&longs;tanding the rece&longs;s of &longs;o ma<lb/>ny bubbles as broke on the top of the <lb/>Spirit of Urine, during all the time of the <lb/>Experiment; yet it &longs;carcely appear'd at all <lb/>to be &longs;unk below the mark: Nor did the <lb/>mixture of Spirit of Wine and Water <lb/>con&longs;iderably &longs;ub&longs;ide. </s>

<s>But that is no<lb/>thing to what we ob&longs;erv'd in the Spirit <lb/>of Wine, for not onely it con&longs;picuou&longs;ly <lb/>expanded it &longs;elf in the Neck of the <lb/>Ve&longs;&longs;el that contain'd it, notwith&longs;tand<lb/>ing the largene&longs;s of it; and that the <lb/>bubbles were about to break at the <lb/>top of it almo&longs;t a&longs;&longs;oon as they arriv'd <lb/>there: but upon the re-admi&longs;&longs;ion of <lb/>the external Air, the Spirit of Wine <lb/>retain'd its newly acquired expan&longs;ion. <lb/>And though we let it alone for near <lb/>an hour together, in expectation that it <lb/>might &longs;ub&longs;ide; yet when we took it <lb/>out, we found it &longs;till &longs;well'd between a <lb/>quarter and half an Inch above the <lb/>mark; and although it was not ea&longs;ily <pb pagenum="195"/>imaginable how this <emph type="italics"/>Phænomenon<emph.end type="italics"/> could <lb/>proceed from any mi&longs;take in trying <lb/>the Experiment, yet the &longs;trangene&longs;&longs;e <lb/>of it invited me to repeat it with fre&longs;h <lb/>Spirit of Wine; which, &longs;welling in the <lb/>Neck as formerly, I left all Night in <lb/>the Receiver, allowing free acce&longs;s to the <lb/>external Air at the Stop-cock, and the <lb/>next day found it &longs;till expanded as be<lb/>fore, &longs;ave that it &longs;eem'd a little lower: <lb/>which decrement perhaps proceeded from <lb/>the avolation of &longs;ome of the fugitive <lb/>parts of &longs;o volatile a Liquor. </s>

<s>And though we let it alone for near <lb/>an hour together, in expectation that it <lb/>might &longs;ub&longs;ide; yet when we took it <lb/>out, we found it &longs;till &longs;well'd between a <lb/>quarter and half an Inch above the <lb/>mark; and although it was not ea&longs;ily <pb pagenum="195"/>imaginable how this <emph type="italics"/>Phænomenon<emph.end type="italics"/> could <lb/>proceed from any mi&longs;take in trying <lb/>the Experiment, yet the &longs;trangene&longs;&longs;e <lb/>of it invited me to repeat it with fre&longs;h <lb/>Spirit of Wine; which, &longs;welling in the <lb/>Neck as formerly, I left all Night in <lb/>the Receiver, allowing free acce&longs;s to the <lb/>external Air at the Stop-cock, and the <lb/>next day found it &longs;till expanded as be<lb/>fore, &longs;ave that it &longs;eem'd a little lower: <lb/>which decrement perhaps proceeded from <lb/>the avolation of &longs;ome of the fugitive <lb/>parts of &longs;o volatile a Liquor. </s>

<s>And for <lb/>better &longs;atisfaction having taken out the <lb/>Gla&longs;s, and con&longs;ider'd it in the open Air, <lb/>and at a Window, I could not finde that <lb/>there was any remaining Bubbles that <lb/>could occa&longs;ion the per&longs;evering and ad<lb/>mir'd expan&longs;ion. </s>

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<s>The &longs;ucce&longs;s was, That having drawn <lb/>out a pretty quantity of Air, the bubbles <lb/>began to di&longs;clo&longs;e them&longs;elves in the Wa<lb/>ter, as in the former Experiments; and <lb/>though for a good while after the bubbles <lb/>a&longs;cended in &longs;warms from the lower parts <lb/>of the Water, and ha&longs;tily broke at the <lb/>top; yet we pro&longs;ecuted the Experiment <lb/>&longs;o long without &longs;eeing any effect wrought <pb pagenum="197"/>upon the E&longs;&longs;ence: Bottles, that we began <lb/>to di&longs;pair of &longs;eeing either of them ri&longs;e, but <lb/>continuing to ply the Pump, that little <lb/>Gla&longs;s, who&longs;e mouth was open'd, came to <lb/>the top of the Water, being, as it were, <lb/>boy'd up thither by a great number of <lb/>bubbles that had fa&longs;tned them&longs;elves to <lb/>the &longs;ides of it; &longs;wimming thus with the <lb/>mouth downward, we could ea&longs;ily per<lb/>ceive that the internal Air above men<lb/>tion'd had much delated it &longs;elf, and there<lb/>by &longs;eem'd to have contributed to the e<lb/>merging of the Gla&longs;s, which remain'd <lb/>floating, notwith&longs;tanding the breaking <lb/>and vani&longs;hing of mo&longs;t of the contiguous <lb/>bubbles: being hereby incouraged to per<lb/>&longs;i&longs;t in pumping, we ob&longs;erved with &longs;ome <lb/>plea&longs;ure, that at each time we turn'd the <lb/>Key, the Air in the little Gla&longs;s did mani<lb/>fe&longs;tly expand it &longs;elf and thru&longs;t out the wa<lb/>ter, generally retaining a very protuberant <lb/>&longs;urface where it was contiguous to the re<lb/>maining Water. </s>

<s>And when after divers <lb/>ex&longs;uctions of the Air in the Receiver, <lb/>that in the little Viol &longs;o dilated it &longs;elf as <lb/>to expel almo&longs;t all the Water, it turn'd <lb/>up its mouth towards the &longs;urface of the <lb/>Water in the Jar, and there deliver'd a <lb/>large bubble, and then relap&longs;ed into its <pb pagenum="198"/>formér floating po&longs;ture: And this Expe<lb/>riment taught us, among other things, <lb/>that it was a work of more time and la<lb/>bor then we imagin'd, to exhau&longs;t our En<lb/>gine as much as it may be exhau&longs;ted: for <lb/>although before the emerging of the &longs;mall <lb/>Viol, we did (as has been touch'd alrea<lb/>dy) think we had very con&longs;iderably em<lb/>ptyed the Receiver, becau&longs;e there &longs;eem'd <lb/>to come out but very little or almo&longs;t <lb/>no &longs;en&longs;ible Air at each ex&longs;uction into <lb/>and out of the Cylinder; yet after<lb/>wards, at each drawing down the Suc<lb/>ker, the Air included in the Viol did <lb/>manife&longs;tly dilate it &longs;elf, &longs;o long, that <lb/>it did no le&longs;s then nine times turn its <lb/>mouth upwards, and di&longs;charge a bub<lb/>ble by conjecture about the bigne&longs;s of <lb/>a Pea, after the manner newly recited. <lb/>But as for that Violl which had the <lb/>weight in it, it ro&longs;e not at all. </s>

<s>But as for that Violl which had the <lb/>weight in it, it ro&longs;e not at all. </s>

<s>So <lb/>that being not able by quick pumping <lb/>to gain another bubble from the Air <lb/>in the &longs;wimming Gla&longs;s, which proceed<lb/>ed from &longs;ome &longs;mall leak in the Ve&longs;&longs;el, <lb/>though it held in this Experiment more <lb/>&longs;tanch then was u&longs;ual, we thought fit <lb/>to let in lea&longs;urely the Air from with<lb/>out, upon who&longs;e admi&longs;&longs;ion that with-<pb pagenum="199"/>in the Viol &longs;hrinking into a very nar<lb/>row compa&longs;s, the Gla&longs;s did, as we expe<lb/>cted, fall down to the bottom of the <lb/>Jar. </s>

<s>But being de&longs;irous before we proceed<lb/>ed to any new. </s>

<s>Experiment, to try once <lb/>more whether the little Gla&longs;s that had <lb/>the weight in it might not al&longs;o be rai&longs;'d. <lb/>After we had &longs;uffer'd the Engine to re<lb/>main clo&longs;'d as it was, for five or &longs;ix <lb/>hours, the Pump was again ply'd with <lb/>&longs;o much ob&longs;tinacy, that not onely a<lb/>bout the upper part of the Jar there ap<lb/>pear'd a good number of bubbles (but <lb/>very much &longs;maller then tho&longs;e we &longs;aw <lb/>the fir&longs;t time) but afterwards there <lb/>came from the bottom of the Jar, bub<lb/>bles about the bigne&longs;s of &longs;mal Peas: which <lb/>the Pump being &longs;till kept going, fol<lb/>low'd one another, to the number of forty, <lb/>coming from the &longs;topp'd Violl; who&longs;e <lb/>mouth, it &longs;eems, had not been &longs;hut &longs;o <lb/>&longs;trongly and clo&longs;ely, but that the included <lb/>Air, dilating it &longs;elf by its own &longs;pring, made <lb/>it&longs;elf &longs;ome little pa&longs;&longs;age betwixt the Wall <lb/>and the Gla&longs;s, and got away in the&longs;e bub<lb/>bles; after which, the un&longs;topp'd Gla&longs;s be<lb/>gan to float again, the Air &longs;hut up in it <pb pagenum="200"/>being manife&longs;tly &longs;o dilated as to expel a <lb/>good part of the Water, but not &longs;o much <lb/>as to break quite thorow. </s>

<s>Experiment, to try once <lb/>more whether the little Gla&longs;s that had <lb/>the weight in it might not al&longs;o be rai&longs;'d. <lb/></s>

<s>After we had &longs;uffer'd the Engine to re<lb/>main clo&longs;'d as it was, for five or &longs;ix <lb/>hours, the Pump was again ply'd with <lb/>&longs;o much ob&longs;tinacy, that not onely a<lb/>bout the upper part of the Jar there ap<lb/>pear'd a good number of bubbles (but <lb/>very much &longs;maller then tho&longs;e we &longs;aw <lb/>the fir&longs;t time) but afterwards there <lb/>came from the bottom of the Jar, bub<lb/>bles about the bigne&longs;s of &longs;mal Peas: which <lb/>the Pump being &longs;till kept going, fol<lb/>low'd one another, to the number of forty, <lb/>coming from the &longs;topp'd Violl; who&longs;e <lb/>mouth, it &longs;eems, had not been &longs;hut &longs;o <lb/>&longs;trongly and clo&longs;ely, but that the included <lb/>Air, dilating it &longs;elf by its own &longs;pring, made <lb/>it&longs;elf &longs;ome little pa&longs;&longs;age betwixt the Wall <lb/>and the Gla&longs;s, and got away in the&longs;e bub<lb/>bles; after which, the un&longs;topp'd Gla&longs;s be<lb/>gan to float again, the Air &longs;hut up in it <pb pagenum="200"/>being manife&longs;tly &longs;o dilated as to expel a <lb/>good part of the Water, but not &longs;o much <lb/>as to break quite thorow. </s>

<s>And at length, <lb/>when our expectation of it was almo&longs;t ti<lb/>red out, the heavier of the two Viols be<lb/>gan to come aloft, and immediately to <lb/>&longs;ub&longs;ide again, which appear'd to be oc<lb/>ca&longs;ion'd by the Air within it, who&longs;e bulk <lb/>and &longs;pring being weaken'd by the rece&longs;s <lb/>of the forty bubbles before-mention'd, it <lb/>was no longer able, as formerly, to break <lb/>forcibly through the incumbent Water; <lb/>but forming a bubble at the mouth of the <lb/>Gla&longs;s, boyed it up towards the top, and <lb/>there getting away, left it to &longs;ink again <lb/>till the pre&longs;&longs;ure of the Air in the Recei<lb/>ver being further taken off, the Air in the <lb/>Viol was permitted to expand it &longs;elf fur<lb/>ther, and to create another bubble, by <lb/>which it was again for a while carried up. <lb/>And it was remarkable, that though after <lb/>having emptyed the Receiver as far as <lb/>well we could, we cea&longs;'d from pumping; <lb/>yet the Ve&longs;&longs;el continuing more &longs;tanch <lb/>then it was wont, this a&longs;cent and fall of <lb/>the Viol was repeated to the ninth time; <lb/>the included Air, by rea&longs;on of the &longs;mal<lb/>ne&longs;s of the vent at which it mu&longs;t pa&longs;s out, <lb/>being not able to get away otherwi&longs;e then <pb pagenum="201"/>little by little; and con&longs;equently, in divers <lb/>&longs;uch parcels as were able to con&longs;titute <lb/>bubbles, each of them big enough to <lb/>rai&longs;e the Viol and keep it aloft until the <lb/>avolation of that bubble. </s>

<s>And it was remarkable, that though after <lb/>having emptyed the Receiver as far as <lb/>well we could, we cea&longs;'d from pumping; <lb/>yet the Ve&longs;&longs;el continuing more &longs;tanch <lb/>then it was wont, this a&longs;cent and fall of <lb/>the Viol was repeated to the ninth time; <lb/>the included Air, by rea&longs;on of the &longs;mal<lb/>ne&longs;s of the vent at which it mu&longs;t pa&longs;s out, <lb/>being not able to get away otherwi&longs;e then <pb pagenum="201"/>little by little; and con&longs;equently, in divers <lb/>&longs;uch parcels as were able to con&longs;titute <lb/>bubbles, each of them big enough to <lb/>rai&longs;e the Viol and keep it aloft until the <lb/>avolation of that bubble. </s>

<s>Whereby it <lb/>may appear, that the grand rule in <emph type="italics"/>Hy<lb/>dro&longs;taticks,<emph.end type="italics"/> That a Body will &longs;wim in the <lb/>Water, in ca&longs;e it be lighter then as much <lb/>of that Water that equals it in bulk, will <lb/>hold likewi&longs;e when the pre&longs;&longs;ure of the At<lb/>mo&longs;phere is in very great mea&longs;ure, if not <lb/>when it is totally taken off from the Li<lb/>quor and the Body: though it were worth <lb/>inquiring what it is that &longs;o plentifully <lb/>concurs to fill the bubbles made in our <lb/>Experiment by the &longs;o much expanded <lb/>Air, for to &longs;ay with the old Peripatetick <lb/>Schools, That the Air, in Rarefaction, <lb/>may acquire a new extent, without the <lb/>admi&longs;&longs;ion of any new &longs;ub&longs;tance, would <lb/>be an account of the <emph type="italics"/>Phænomenon<emph.end type="italics"/> very <lb/>much out of date, and which, I &longs;uppo&longs;e, <lb/>our Modern Naturali&longs;ts would neither <lb/>give, nor acquie&longs;s in. </s>

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<s>THat the Air is the medium whereby <lb/>&longs;ounds are convey'd to the Ear, has <lb/><arrow.to.target n="marg34"></arrow.to.target><lb/>been for many Ages, and is yet the com<lb/>mon Doctrine of the Schools. </s>

<s>But this <lb/>Received Opinion has been of late op<lb/>po&longs;'d by &longs;ome Philo&longs;ophers upon the ac<lb/>count of an Experiment made by the <lb/>Indu&longs;trious <emph type="italics"/>Kircher,<emph.end type="italics"/> and other Learned <lb/>Men, who have (as they a&longs;&longs;ure us) ob<lb/>&longs;erv'd, That if a Bell, with a Steel Clap<lb/>per, be &longs;o fa&longs;ten'd to the in&longs;ide of a Tube, <lb/>that upon the making the Experiment <emph type="italics"/>De <lb/>Vacuo<emph.end type="italics"/> with that Tube, the Bell remain'd <lb/>&longs;u&longs;pended in the de&longs;erted &longs;pace at the up<lb/>per end of the Tube: And if al&longs;o a vi<lb/>gorous Load-&longs;tone be apply'd on the out<lb/>&longs;ide of the Tube to the Bell, it will at<lb/>tract the Clapper, which upon the Remo<lb/>val of the Load-&longs;tone falling back, will <lb/>&longs;trike again&longs;t the oppo&longs;ite &longs;ide of the <lb/>Bell, and thereby produce a very audible <lb/>&longs;ound, whence divers have concluded, <lb/>That 'tis not the Air, but &longs;ome more &longs;ub<lb/>tle Body that is the medium of &longs;ounds. <lb/>But becau&longs;e we conceiv'd that, to invali<lb/>date &longs;uch a con&longs;equence from this ingeni<lb/>ous Experiment (though the mo&longs;t lucife-<pb pagenum="206"/>rous, that could well be made without <lb/>&longs;ome &longs;uch Engine as ours) &longs;ome things <lb/>might be &longs;peciou&longs;ly enough alleadg'd; we <lb/>thought fit to make a tryal or two, in or<lb/>der to the Di&longs;covery of what the Air does <lb/>in conveying of &longs;ounds, re&longs;erving divers <lb/>other Experiments tryable in our Engine <lb/>concerning &longs;ounds, till we can obtain more <lb/>lea&longs;ure to pro&longs;ecute them. </s>

<s>But becau&longs;e we conceiv'd that, to invali<lb/>date &longs;uch a con&longs;equence from this ingeni<lb/>ous Experiment (though the mo&longs;t lucife-<pb pagenum="206"/>rous, that could well be made without <lb/>&longs;ome &longs;uch Engine as ours) &longs;ome things <lb/>might be &longs;peciou&longs;ly enough alleadg'd; we <lb/>thought fit to make a tryal or two, in or<lb/>der to the Di&longs;covery of what the Air does <lb/>in conveying of &longs;ounds, re&longs;erving divers <lb/>other Experiments tryable in our Engine <lb/>concerning &longs;ounds, till we can obtain more <lb/>lea&longs;ure to pro&longs;ecute them. </s>

<s>Conceiving it <lb/>then the be&longs;t way to make our tryal with <lb/>&longs;uch a noi&longs;e as might not be loud enough <lb/>to make it difficult to di&longs;cern &longs;lighter va<lb/>riations in it, but rather might be, both <lb/>la&longs;ting, that we might take notice by what <lb/>degrees it decrea&longs;'d; and &longs;o &longs;mall, that <lb/>it could not grow much weaker with<lb/>out becoming imperceptible. </s>

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<s>And it was ob&longs;erva<lb/>ble to this purpo&longs;e, that we found a mani<lb/>fe&longs;t di&longs;parity of noi&longs;e, by holding our Ears <lb/>near the &longs;ides of the Receiver, and near the <lb/>Cover of it: which difference &longs;eem'd to <lb/>proceed from that of the Texture of the <lb/>Gla&longs;s, from the &longs;tructure of the cover (and <lb/>of the Cement) through which the &longs;ound <lb/>was propagated from the Watch to the <lb/>Ear. </s>

<s>But let us pro&longs;ecute our Experiment. <lb/>The Pump after this being imployd, it <lb/>&longs;eemd that from time to time the &longs;ound <lb/>grew fainter and fainter; &longs;o that when the <lb/>Rec iver was empty'd as much as it u&longs;'d <lb/>to be for the foregoing Experiments, nei<lb/>ther we, nor &longs;ome &longs;trangers that chanc'd <lb/>to be then in the room, could, by applying <lb/>our Ears to the very &longs;ides, hear any noi&longs;e <lb/>from within; though we could ea&longs;ily per<lb/>ceive that by the moving of the hand <lb/>which mark'd the &longs;econd minutes, and by <lb/>that of the ballance, that the Watch nei<lb/>ther &longs;tood &longs;til, nor remarkably varied from <lb/>its wonted motion. </s>

<s>But let us pro&longs;ecute our Experiment. <lb/></s>

<s>The Pump after this being imployd, it <lb/>&longs;eemd that from time to time the &longs;ound <lb/>grew fainter and fainter; &longs;o that when the <lb/>Rec iver was empty'd as much as it u&longs;'d <lb/>to be for the foregoing Experiments, nei<lb/>ther we, nor &longs;ome &longs;trangers that chanc'd <lb/>to be then in the room, could, by applying <lb/>our Ears to the very &longs;ides, hear any noi&longs;e <lb/>from within; though we could ea&longs;ily per<lb/>ceive that by the moving of the hand <lb/>which mark'd the &longs;econd minutes, and by <lb/>that of the ballance, that the Watch nei<lb/>ther &longs;tood &longs;til, nor remarkably varied from <lb/>its wonted motion. </s>

<s>And to &longs;atisfie our <lb/>&longs;elvs further that it was indeed the ab&longs;ence <lb/>of the Air about the Watch that hinder'd <lb/>us from hearing it, we let in the external <lb/>Air at the Stop-cock, and then though we <pb pagenum="208"/>turn'd the Key and &longs;topt the Valve, yet we <lb/>could plainly hear the noi&longs;e made by the <lb/>ballance, though we held our Ears &longs;ome<lb/>times at two Foot di&longs;tance from the out<lb/>&longs;ide of the Receiver. </s>

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<s><margin.target id="marg35"></margin.target><emph type="italics"/>Experi<lb/>ment<emph.end type="italics"/> 28.</s>

<s>We convey'd into the Receiver a new <lb/>Gla&longs;s Viol, capable of holding about 6 or <lb/>7 ounces of Water, into which we had <lb/>before put 2 or 3 Spoon-fulls of that Li<lb/>quor, and &longs;topt it clo&longs;e with a fit Cork. <lb/>The Pneumatical Ve&longs;&longs;el being empty'd, <lb/>there appear'd not any change in the in<lb/>clo&longs;'d Water, the Air impri&longs;on'd with it, <lb/>not having the force to blow out the &longs;top-<pb pagenum="215"/>ple, which event, though it were no other <lb/>then we expected, was differing from what <lb/>we de&longs;ir'd. </s>

<s>The Pneumatical Ve&longs;&longs;el being empty'd, <lb/>there appear'd not any change in the in<lb/>clo&longs;'d Water, the Air impri&longs;on'd with it, <lb/>not having the force to blow out the &longs;top-<pb pagenum="215"/>ple, which event, though it were no other <lb/>then we expected, was differing from what <lb/>we de&longs;ir'd. </s>

<s>For we would gladly have &longs;een <lb/>what change would have appear'd in the <lb/>Water upon the Bottles being &longs;uddenly <lb/>un&longs;topp'd, in a place where the ambient <lb/>Body was &longs;o differing from our common <lb/>Air. </s>

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<s>Now to mani<lb/>fe&longs;t that this &longs;moak thus &longs;etled emulated <pb pagenum="225"/>a Liquor, we inclin'd the Engine that con<lb/>tain'd it, &longs;ometimes to one &longs;ide, and &longs;ome<lb/>times to the other; and ob&longs;erv'd the <lb/>&longs;moak to keep its &longs;urface almo&longs;t Hori<lb/>zontal, notwith&longs;tanding the &longs;tooping of <lb/>the Ve&longs;&longs;el that held it, as Water or an<lb/>other Liquor would in the like ca&longs;e have <lb/>done. </s>

<s>And if by a quicker rocking of the <lb/>Engine the &longs;moke were more &longs;wiftly &longs;ha<lb/>ken, it would, like Water, either Vibrate <lb/>to and fro from one &longs;ide to the other of <lb/>the Gla&longs;s, or el&longs;e have its &longs;urface manife&longs;t<lb/>ly curll'd with Waves, but pre&longs;erve its <lb/>&longs;elf in an intire and di&longs;tinct Body from the <lb/>incumbent Air; and being permitted to <lb/>re&longs;t awhile, would &longs;oon recover its for<lb/>mer &longs;mooth and level <emph type="italics"/>&longs;uperficies:<emph.end type="italics"/> If al&longs;o <lb/>the Key were turn'd and the Valve un<lb/>&longs;topp'd, &longs;o that there was a free, though <lb/>but a narrow pa&longs;&longs;age open'd betwixt the <lb/>external Air and the cavity of the Recei<lb/>ver, then would &longs;ome of this &longs;moak fall <lb/>down, as it were, in a &longs;tream into the &longs;ub<lb/>jacent Cylinder, and a proportionate <lb/>quantity of the outward Air, would ma<lb/>nife&longs;tly a&longs;cend through it into the incum<lb/>bent Air, much after the &longs;ame manner as <lb/>if you invert a Viol with a long Neck, and <lb/>well fill'd with Red-Wine, into a Gla&longs;s <pb pagenum="226"/>full of fair water, you &longs;hall &longs;ee the Water <lb/>and Wine by degrees mingle with one an<lb/>other; the one falling downe as it were in <lb/>little colour'd &longs;treames, and the other a&longs;<lb/>cending into its room in the like curled <lb/>&longs;treames, &longs;ometimes preceded by round <lb/>parcels of water, which, by rea&longs;on of their <lb/>tran&longs;parency, looke almo&longs;t like bubbles. <lb/>The other circum&longs;tances of this Experi<lb/>ment, belonging not all of them to our <lb/>pre&longs;ent purpo&longs;e, we &longs;hall content our <lb/>&longs;elves with taking notice of one which <lb/>&longs;eemes the mo&longs;t important, and may illu<lb/>&longs;trate and confirme &longs;ome things former<lb/>ly delivered. </s>

<s>The other circum&longs;tances of this Experi<lb/>ment, belonging not all of them to our <lb/>pre&longs;ent purpo&longs;e, we &longs;hall content our <lb/>&longs;elves with taking notice of one which <lb/>&longs;eemes the mo&longs;t important, and may illu<lb/>&longs;trate and confirme &longs;ome things former<lb/>ly delivered. </s>

<s>And it was, That if, when <lb/>the <emph type="italics"/>&longs;uperficies<emph.end type="italics"/> of our Smoke lay &longs;mooth <lb/>and horizontal, a hot iron were held near <lb/>the our &longs;ide of the Receiver, the Neigh<lb/>bouring part of the included fumes (for <lb/>the re&longs;t did not very much alter their for<lb/>mer <emph type="italics"/>&longs;uperficies<emph.end type="italics"/>) being rarified by the heat, <lb/>would readily a&longs;cend in a large Pillar of <lb/>&longs;moke to the very top of the Receiver, <lb/>yet without &longs;eeming to loo&longs;e a di&longs;tinct <lb/><emph type="italics"/>&longs;uperficies,<emph.end type="italics"/> or to be confounded with Air; <lb/>below which, upon the rece&longs;s of the ad<lb/>ventitious heat that by agitating it im<lb/>pell'd it upward, it would againe &longs;ub<lb/>&longs;ide. </s><pb pagenum="227"/>

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<s>I <lb/>&longs;peake thus diffidently upon this occa&longs;ion <lb/>becau&longs;e I know that by the Fluctuation or <pb pagenum="228"/>Boyling of the Sun's own <emph type="italics"/>&longs;uperficies<emph.end type="italics"/> di<lb/>ver&longs;e eminent Mathematicians have plau<lb/>&longs;ibly enough (but how truly I leave <lb/>your Lord&longs;hip to Judge) endeavour'd to <lb/>give an Account of it. </s>

<s>But if we will joine <lb/>with tho&longs;e that have a&longs;crib'd of late this <lb/><emph type="italics"/>Phænomenon<emph.end type="italics"/> to the Refraction the Sun<lb/>Beames fuffer in our vapid Air; we may, <lb/>as hath been intimated, promote their Do<lb/>ctrin by deducing from it, that probably <lb/>the &longs;urface Atmo&longs;phere is oftentimes (if <lb/>not alwayes) exceedingly curl'd or wav'd. <lb/>And certainly it is &longs;omewhat wonderfull <lb/>as well as very plea&longs;ant to behold, how, <lb/>to him that looks upon the &longs;etting Sun <lb/>through a long & excellent Tele&longs;cope, <lb/>there will not only appeare &longs;trange ine<lb/>qualities in the edge of it (in&longs;omuch that <lb/>I have often &longs;een it more indented than a <lb/>Saw) but tho&longs;e inequalities will vani&longs;h in <lb/>one place and pre&longs;ently appeare in ano<lb/>ther, and &longs;eem perfectly to move like <lb/>waves &longs;ucceeding and de&longs;troying one an<lb/>other; &longs;ave that their Motion oftentimes <lb/>&longs;eemes to be quicke&longs;t as if in that va&longs;t &longs;ea <lb/>they were carried on by a current, or at <lb/>lea&longs;t by a tide. </s>

<s>And certainly it is &longs;omewhat wonderfull <lb/>as well as very plea&longs;ant to behold, how, <lb/>to him that looks upon the &longs;etting Sun <lb/>through a long & excellent Tele&longs;cope, <lb/>there will not only appeare &longs;trange ine<lb/>qualities in the edge of it (in&longs;omuch that <lb/>I have often &longs;een it more indented than a <lb/>Saw) but tho&longs;e inequalities will vani&longs;h in <lb/>one place and pre&longs;ently appeare in ano<lb/>ther, and &longs;eem perfectly to move like <lb/>waves &longs;ucceeding and de&longs;troying one an<lb/>other; &longs;ave that their Motion oftentimes <lb/>&longs;eemes to be quicke&longs;t as if in that va&longs;t &longs;ea <lb/>they were carried on by a current, or at <lb/>lea&longs;t by a tide. </s>

<s>And this (as we el&longs;e <lb/>where note) appear's to the eye not on<lb/>ly when it looks directly through the te-<pb pagenum="229"/>le&longs;cope upon the &longs;unne; but al&longs;o when a <lb/>large and well defin'd image of the &longs;unne <lb/>is by the &longs;ame tele&longs;cope brought into a <lb/>roome and ca&longs;t upon a &longs;heet of white pa<lb/>per. </s>

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<s>Fuveni<emph.end type="italics"/> (&longs;ays he) <lb/><emph type="italics"/>lacertorum &longs;uorum robur: jactanti propo<lb/>&longs;ita &longs;emel e&longs;t lamina ærea, per an&longs;am in <lb/>medio extantem apprehen&longs;am elevanda è <lb/>tabula marmorea, cui optime congruebat: <lb/>qui primo tanquam rem ludicr am puero <lb/>committendam contemp&longs;it: tum in&longs;tanti<lb/>bus amicis manum utrámque admovens, <lb/>cum luctatus diu hærentem non removi&longs;&longs;et, <lb/>excu&longs;avit impotentiam, objecta perigrini <lb/>& potenti&longs;simi glutinis interpo&longs;itione, quo <lb/>forti&longs;sime copulante nequiret divelli; do<lb/>nec vidit ab alio per tabulam facilimè lami<lb/>nam deduci, & ad extrema product am, & <lb/>actam in tran&longs;ver&longs;um inàe deportari.<emph.end type="italics"/> But <lb/>that we may learn from our own Engine, <pb pagenum="233"/>that two Bodies, though they touch each <lb/>other but in a &longs;mall part of their &longs;urfaces, <lb/>may be made to cohere very &longs;trongly, <lb/>onely by this, That the Air pre&longs;&longs;es much <lb/>more forcibly upon the inferior &longs;uperfi<lb/>cies of the lowermo&longs;t Body, then upon <lb/>the upper &longs;urface of the &longs;ame: We will <lb/>hereunto annex the following Experi<lb/>ment, though out of the order wherein <lb/>they were made. <lb/><arrow.to.target n="marg40"></arrow.to.target></s>

<s><margin.target id="marg39"></margin.target><emph type="italics"/>P. Nic. <lb/>Zucchius <lb/>opal Schot: <lb/>part<emph.end type="italics"/> 1. <lb/><gap/></s>

<s>Zucchius <lb/>opal Schot: <lb/>part<emph.end type="italics"/> 1. <lb/><gap/></s>

<s><margin.target id="marg40"></margin.target><emph type="italics"/>Experi<lb/>ment<emph.end type="italics"/> 32.</s>

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<s>This done the key of the Stop-cock <lb/>was turn'd, and the externall Air beating <lb/>like a forcible &longs;treame upon the Valve <lb/>to get in there, it did &longs;uddenly both &longs;hut <lb/>the Valve and keep it &longs;hut &longs;o &longs;trongly, <lb/>that we had time to ca&longs;t in diver&longs;e weights <lb/>one after another into the Scale; till at <lb/>length the weight overpowering the pre&longs;<lb/>&longs;ure of the Atmo&longs;phere, drew downe the <lb/>Valve by the &longs;tringes that ty'd the Scale <lb/>to it, and gave liberty to the outward Air <lb/>to ru&longs;h into the Receiver. </s>

<s>Though a-<pb pagenum="235"/>nother time, when the Valve had but lit<lb/>tle weight hanging at it, being, by I know <lb/>not what accident, drawn down beneath its <lb/>former place, it was by the impetuous <lb/>current of the outward Air &longs;uddenly im<lb/>pell'd up into it again, and kept there. <lb/>But in the former Experiment it is re<lb/>markable, That though the Receiver were <lb/>not well exhau&longs;ted, and though it leak'd <lb/>whil'&longs;t the re&longs;t of the Experiment was in <lb/>pro&longs;ecution, and though the Valve <lb/>whereon the Cylinder of the Atmo&longs;phere <lb/>could pre&longs;s, were not above an Inch and <lb/>a half in Diameter, yet the weight kept <lb/>up by &longs;uction, or rather &longs;upported by the <lb/>Air, namely the Valve, the Seal and <lb/>what was ca&longs;t into it, being &longs;ent to be <lb/>weigh'd, amounted to about ten of our <lb/>common Pounds, con&longs;i&longs;ting of &longs;ixteen <lb/>Ounces apiece: So that we doubted not <lb/>but that, had the Experiment been made <lb/>with favorable Circum&longs;tances, the Air <lb/>endeavoring to pre&longs;s in at the Orifice of <lb/>the Stop-cock, would have kept a very <lb/>much greater weight from falling out of <lb/>it; I &longs;ay the Air, becau&longs;e we found, by <lb/>tryal purpo&longs;ely made, that neither the <lb/>imperfect contact of the Valve and the <lb/>Stop-cock, nor the Diachylon that was <pb pagenum="236"/>employ'd to fill up the little Crannies left <lb/>betwixt them, were con&longs;iderable in this <lb/>Experiment; by which may among other <lb/>things appear, that I did not without <lb/>cau&longs;e in the above-nam'd Di&longs;cour&longs;e touch<lb/>ing Fluidity and Firmne&longs;s, a&longs;cribe a great <lb/>force, ev'n to &longs;uch Pillars of Air as may <lb/>be &longs;uppo&longs;'d to begin at the top of the <lb/>Atmo&longs;phere, and recoyling from the <lb/>ground to terminate on the Bodies on <lb/>which they pre&longs;s: &longs;ince in the pre&longs;ent Ex<lb/>periment &longs;uch a weight was &longs;upported by <lb/>&longs;o &longs;lender a Cylinder of Air, rebounding <lb/>from the Earth to the Valve whereon it <lb/>did bear. </s>

<s>But in the former Experiment it is re<lb/>markable, That though the Receiver were <lb/>not well exhau&longs;ted, and though it leak'd <lb/>whil'&longs;t the re&longs;t of the Experiment was in <lb/>pro&longs;ecution, and though the Valve <lb/>whereon the Cylinder of the Atmo&longs;phere <lb/>could pre&longs;s, were not above an Inch and <lb/>a half in Diameter, yet the weight kept <lb/>up by &longs;uction, or rather &longs;upported by the <lb/>Air, namely the Valve, the Seal and <lb/>what was ca&longs;t into it, being &longs;ent to be <lb/>weigh'd, amounted to about ten of our <lb/>common Pounds, con&longs;i&longs;ting of &longs;ixteen <lb/>Ounces apiece: So that we doubted not <lb/>but that, had the Experiment been made <lb/>with favorable Circum&longs;tances, the Air <lb/>endeavoring to pre&longs;s in at the Orifice of <lb/>the Stop-cock, would have kept a very <lb/>much greater weight from falling out of <lb/>it; I &longs;ay the Air, becau&longs;e we found, by <lb/>tryal purpo&longs;ely made, that neither the <lb/>imperfect contact of the Valve and the <lb/>Stop-cock, nor the Diachylon that was <pb pagenum="236"/>employ'd to fill up the little Crannies left <lb/>betwixt them, were con&longs;iderable in this <lb/>Experiment; by which may among other <lb/>things appear, that I did not without <lb/>cau&longs;e in the above-nam'd Di&longs;cour&longs;e touch<lb/>ing Fluidity and Firmne&longs;s, a&longs;cribe a great <lb/>force, ev'n to &longs;uch Pillars of Air as may <lb/>be &longs;uppo&longs;'d to begin at the top of the <lb/>Atmo&longs;phere, and recoyling from the <lb/>ground to terminate on the Bodies on <lb/>which they pre&longs;s: &longs;ince in the pre&longs;ent Ex<lb/>periment &longs;uch a weight was &longs;upported by <lb/>&longs;o &longs;lender a Cylinder of Air, rebounding <lb/>from the Earth to the Valve whereon it <lb/>did bear. </s>

<s>BUt in regard we have not yet been <lb/><arrow.to.target n="marg41"></arrow.to.target><lb/>able to empty &longs;o great a Ve&longs;&longs;el as our <lb/>Receiver, &longs;o well as we can the Cylinder <lb/>it &longs;elf; our Pump alone may afford us a <lb/>nobler in&longs;tance of the fotce of the Air we <lb/>live in, in&longs;omuch, that by help of this <lb/>part of our Engine, we may give a pretty <lb/>near ghe&longs;s at the &longs;trength of the Atmo<lb/>&longs;phere, computed as a weight. </s>

<s>And the <lb/>way may be this; Fir&longs;t, the Sucker be<lb/>ing brought to move ea&longs;ily up and down <lb/>the Cylinder, is to be impell'd to the top <pb pagenum="237"/>of it: Then the Receiver mu&longs;t be taken <lb/>off from the Pump, that the upper Ori<lb/>fice of the Cylinder remaining open, the <lb/>Air may freely &longs;ucceed the Sucker, and <lb/>therefore readily yield to its motion <lb/>downward. </s>

<s>This done, there mu&longs;t be <lb/>fa&longs;ten'd to one of the Iron Teeth of the <lb/>Sucker, &longs;uch a weight as may ju&longs;t &longs;uffice <lb/>to draw it to the bottom of the Cylinder. <lb/>And having thus examin'd what weight is <lb/>nece&longs;&longs;ary to draw down the Sucker, when <lb/>the Atmo&longs;phere makes no other then the <lb/>ordinary re&longs;i&longs;tance of the Air again&longs;t its <lb/>de&longs;cent; the Sucker mu&longs;t be again forc'd <lb/>to the top of the Cylinder, who&longs;e upper <lb/>Orifice mu&longs;t now be exactly clo&longs;ed; and <lb/>then (the fir&longs;t weight remaining) we ea&longs;i<lb/>ly may, by hanging a Scale to the above<lb/>mention'd Iron (that makes part of the <lb/>Sucker) ca&longs;t in known weights &longs;o long, <lb/>till in &longs;pight of the reluctancy of the At<lb/>mo&longs;phere the Sucker be drawn down. </s>

<s>And having thus examin'd what weight is <lb/>nece&longs;&longs;ary to draw down the Sucker, when <lb/>the Atmo&longs;phere makes no other then the <lb/>ordinary re&longs;i&longs;tance of the Air again&longs;t its <lb/>de&longs;cent; the Sucker mu&longs;t be again forc'd <lb/>to the top of the Cylinder, who&longs;e upper <lb/>Orifice mu&longs;t now be exactly clo&longs;ed; and <lb/>then (the fir&longs;t weight remaining) we ea&longs;i<lb/>ly may, by hanging a Scale to the above<lb/>mention'd Iron (that makes part of the <lb/>Sucker) ca&longs;t in known weights &longs;o long, <lb/>till in &longs;pight of the reluctancy of the At<lb/>mo&longs;phere the Sucker be drawn down. </s>

<s>For <lb/>to the&longs;e weights in the Scale, that of the <lb/>Scale it &longs;elf being added, the &longs;um will give <lb/>us the weight of a Column of Air, equal <lb/>in Diameter to the Sucker, or to the ca<lb/>vity of the Cylinder; and in length to <lb/>the heighth of the Atmo&longs;phere. </s>

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<s>According to this method we did, &longs;ince <pb pagenum="238"/>the writing of the la&longs;t Experiment, at<lb/>tempt to mea&longs;ure the pre&longs;&longs;ure of the At<lb/>mo&longs;phere, but found it more difficult then <lb/>we expected, to perform it with any ac<lb/>curatene&longs;s; for though by the help of the <lb/><emph type="italics"/>Manubrium<emph.end type="italics"/> the Sucker moved up and <lb/>down with &longs;o much ea&longs;e, that one would <lb/>have thought that both its convex &longs;urface, <lb/>and the concave one of the Cylinder were <lb/>exqui&longs;itely &longs;mooth, & as it were &longs;lippery; <lb/>yet when the Sucker came to be moved <lb/>onely with a dead weight or pre&longs;&longs;ure (that <lb/>was not (like the force of him that <lb/>pump'd) intended as occa&longs;ion required) <lb/>we found that the little rufne&longs;&longs;es, or other <lb/>inequalities, and perhaps too, the unequal <lb/>pre&longs;&longs;ure of the Leather again&longs;t the cavity <lb/>of the Cylinder, were able now and then <lb/>to put a &longs;top to the de&longs;cent or a&longs;cent of <lb/>the Sucker, though a very little external <lb/>help would ea&longs;ily &longs;urmount that impedi<lb/>ment; and then the Sucker would, for a <lb/>while, continue its formerly interrupted <lb/>motion, though that a&longs;&longs;i&longs;tance were with<lb/>drawn. </s>

<s>But this di&longs;couragement did not <lb/>deterre us from pro&longs;ecuting our Experi<lb/>ment, and endeavoring, by a careful trial, <lb/>to make it as in&longs;tructive as we could. <lb/>We found then that a Leaden Weight, <pb pagenum="239"/>of 28 pounds (each con&longs;i&longs;ting of &longs;ixteen <lb/>Ounces) being fa&longs;tned to one of the teeth <lb/>of the Sucker, drew it down &longs;lowly e<lb/>nough; when the upper Orifice of the <lb/>Cylinder was left open, though by the <lb/>help of Oyl and Water, and by the fre<lb/>quent moving the Sucker up and down <lb/>with the <emph type="italics"/>Manubrium,<emph.end type="italics"/> its motion in the <lb/>Cylinder had been before purpo&longs;ely faci<lb/>litated. </s>

<s>But this di&longs;couragement did not <lb/>deterre us from pro&longs;ecuting our Experi<lb/>ment, and endeavoring, by a careful trial, <lb/>to make it as in&longs;tructive as we could. <lb/></s>

<s>We found then that a Leaden Weight, <pb pagenum="239"/>of 28 pounds (each con&longs;i&longs;ting of &longs;ixteen <lb/>Ounces) being fa&longs;tned to one of the teeth <lb/>of the Sucker, drew it down &longs;lowly e<lb/>nough; when the upper Orifice of the <lb/>Cylinder was left open, though by the <lb/>help of Oyl and Water, and by the fre<lb/>quent moving the Sucker up and down <lb/>with the <emph type="italics"/>Manubrium,<emph.end type="italics"/> its motion in the <lb/>Cylinder had been before purpo&longs;ely faci<lb/>litated. </s>

<s>This done, the upper Orifice of <lb/>the Cylinder was very carefully and clo&longs;e<lb/>ly &longs;topp'd, the Valve being likewi&longs;e &longs;hut <lb/>with its wonted Stopple well oyl'd, af<lb/>ter the Sucker had been again impell'd <lb/>up to the top of the Cylinder. </s>

<s>Then to <lb/>the precedent twenty eight pound, we <lb/>added a hundred and twelve pounds more, <lb/>which forcing down the Sucker, though <lb/>but lei&longs;urely, we took off the twenty <lb/>eight pound weight; and being unable to <lb/>procure ju&longs;t &longs;uch weights as we would <lb/>have had, we hung on, in&longs;tead of it, one <lb/>of fourteen pound, but found that, with <lb/>the re&longs;t, unable to carry down the Sucker. <lb/>And to &longs;atisfie our &longs;elves, and the Spe<lb/>ctators, that it was the re&longs;i&longs;tance of the <lb/>ambient Air that hinder'd the de&longs;cent of <lb/>&longs;o great a weight, after that we had try'd <lb/>that upon un&longs;topping the Valve, and <pb pagenum="240"/>thereby opening an acce&longs;s to the external <lb/>Air, the Sucker would be immediately <lb/>drawn down: After this, I &longs;ay, we made <lb/>this further Experiment, That having by <lb/>a Man's &longs;trength forcibly depre&longs;&longs;'d the <lb/>Sucker to the bottom of the Cylinder, <lb/>and then fa&longs;tned weights to the above<lb/>named Iron that makes part of that Suc<lb/>ker, the pre&longs;&longs;ure of the external Air find<lb/>ing little or nothing in the cavity of the <lb/>evacuated Cylinder to re&longs;i&longs;t it, did pre<lb/>&longs;ently begin to impell the Sucker, with <lb/>the weights that clogg'd it, towards the <lb/>upper part of the Cylinder, till &longs;ome <lb/>&longs;uch accidental Impediment as we former<lb/>ly mention'd, check'd its cour&longs;e; and <lb/>when that rub, which ea&longs;ily might be, was <lb/>taken out of the way, it would continue <lb/>its a&longs;cent to the top, to the no &longs;mall won<lb/>der of tho&longs;e By &longs;tanders, that could not <lb/>comprehend how &longs;uch a weight could a&longs;<lb/>cend, as it were, of it &longs;elf; that is, with<lb/>out any vi&longs;ible force, or &longs;o much as Su<lb/>ction to lift it up. </s>

<s>And to &longs;atisfie our &longs;elves, and the Spe<lb/>ctators, that it was the re&longs;i&longs;tance of the <lb/>ambient Air that hinder'd the de&longs;cent of <lb/>&longs;o great a weight, after that we had try'd <lb/>that upon un&longs;topping the Valve, and <pb pagenum="240"/>thereby opening an acce&longs;s to the external <lb/>Air, the Sucker would be immediately <lb/>drawn down: After this, I &longs;ay, we made <lb/>this further Experiment, That having by <lb/>a Man's &longs;trength forcibly depre&longs;&longs;'d the <lb/>Sucker to the bottom of the Cylinder, <lb/>and then fa&longs;tned weights to the above<lb/>named Iron that makes part of that Suc<lb/>ker, the pre&longs;&longs;ure of the external Air find<lb/>ing little or nothing in the cavity of the <lb/>evacuated Cylinder to re&longs;i&longs;t it, did pre<lb/>&longs;ently begin to impell the Sucker, with <lb/>the weights that clogg'd it, towards the <lb/>upper part of the Cylinder, till &longs;ome <lb/>&longs;uch accidental Impediment as we former<lb/>ly mention'd, check'd its cour&longs;e; and <lb/>when that rub, which ea&longs;ily might be, was <lb/>taken out of the way, it would continue <lb/>its a&longs;cent to the top, to the no &longs;mall won<lb/>der of tho&longs;e By &longs;tanders, that could not <lb/>comprehend how &longs;uch a weight could a&longs;<lb/>cend, as it were, of it &longs;elf; that is, with<lb/>out any vi&longs;ible force, or &longs;o much as Su<lb/>ction to lift it up. </s>

<s>And indeed it is very <lb/>con&longs;iderable, that though po&longs;&longs;ibly there <lb/>might remain &longs;ome particles of Air in the <lb/>Cylinder, after the drawing down of the <lb/>Sucker; yet the pre&longs;&longs;ure of a Cylinder of <lb/>the Atmo&longs;phere, &longs;omewhat le&longs;s then <pb pagenum="241"/>three Inches in Diameter (for, as it was <lb/>&longs;aid in the de&longs;cription of our Engine, the <lb/>cavity of the Cylinder was no broader) <lb/>was able, uncompre&longs;&longs;'d, not only to &longs;u&longs;tain, <lb/>but even to drive up a weight of an hun<lb/>dred and odde pounds: for be&longs;ides the <lb/>weight of the whole Sucker it &longs;elf, which <lb/>amounts to &longs;ome pounds, the weights an<lb/>nexed to it made up a hundred and three <lb/>pounds, be&longs;ides an Iron Bar, that by con<lb/>jecture weighed two pounds more; and <lb/>yet all the&longs;e together fall &longs;omewhat &longs;hort <lb/>of the weight which we lately mention'd, <lb/>the re&longs;i&longs;tance of the Air to have held &longs;u<lb/>&longs;pended in the cavity of the Cylinder. </s>

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Line 1941

<s>To ob<lb/>ject here, that it was &longs;ome particles of <lb/>Air remaining in the empty'd Cylin-<pb pagenum="245"/>der that attracted this weight to obviate <lb/>a <emph type="italics"/>Vacuum,<emph.end type="italics"/> will &longs;carce be &longs;atisfactory; un<lb/>le&longs;s it can be cleerly made out by what li<lb/>tle hooks, or other grappling In&longs;truments, <lb/>the internal Air could take hold of the <lb/>Sucker; how &longs;o litle of it obtain'd the <lb/>force to lift up &longs;o great a weight; and why <lb/>al&longs;o, upon the letting in of a litle more <lb/>Air into one of our evacuated Ve&longs;<lb/>&longs;els, the attraction is, in&longs;tead of being <lb/>&longs;trengthen'd, much weaken'd, though, <lb/>if there were danger of a <emph type="italics"/>Vacuum<emph.end type="italics"/> be<lb/>fore, it would remain, notwith&longs;tanding <lb/>this ingre&longs;s of a little Air. </s>

<s>For that &longs;till <lb/>there remain'd in the capacity of the ex<lb/>hau&longs;ted Cylinder &longs;tore of little rooms, <lb/>or &longs;paces empty or devoid of Air, may <lb/>appear by the great violence wherewith <lb/>the air ru&longs;hes in, if any way be open'd to it. <lb/>And that 'tis not &longs;o much the decrement <lb/>of the <emph type="italics"/>Vacuum<emph.end type="italics"/> within the cavity of the <lb/>ve&longs;&longs;el that debilitates the attraction, as the <lb/>&longs;pring of the included air (who&longs;e pre&longs;ence <lb/>makes the decrement) that does it by <lb/>re&longs;i&longs;ting the pre&longs;&longs;ure of the external Air, <lb/>&longs;eems probable, partly from the Di&longs;abi<lb/>lity of vacuities, whether greater or le&longs;&longs;er, <lb/>to re&longs;i&longs;t the pre&longs;&longs;ure of the Air; and part<lb/>ly by &longs;ome of the <emph type="italics"/>Phænomena<emph.end type="italics"/> of our Ex-<pb pagenum="246"/>periments, and particularly by this Cir<lb/>cum&longs;tance of the three and Thirtieth, <lb/>that the Sucker was by the pre&longs;&longs;ure of the <lb/>Ambient Air impell'd upwards, with its <lb/>weight hanging at it, not only when it <lb/>was at the bottome of the Cylinder, and <lb/>con&longs;equently left a great <emph type="italics"/>Vacuum<emph.end type="italics"/> in the <lb/>cavity of it; but when the Sucker had <lb/>been already impel'd almo&longs;t to the top of <lb/>the Cylinder, and con&longs;equently, when the <lb/><emph type="italics"/>Vacuum<emph.end type="italics"/> that remain'd was become very <lb/>litle in compari&longs;on of that which preceded <lb/>the beginning of the Sucker's a&longs;cention. </s>

<s>And that 'tis not &longs;o much the decrement <lb/>of the <emph type="italics"/>Vacuum<emph.end type="italics"/> within the cavity of the <lb/>ve&longs;&longs;el that debilitates the attraction, as the <lb/>&longs;pring of the included air (who&longs;e pre&longs;ence <lb/>makes the decrement) that does it by <lb/>re&longs;i&longs;ting the pre&longs;&longs;ure of the external Air, <lb/>&longs;eems probable, partly from the Di&longs;abi<lb/>lity of vacuities, whether greater or le&longs;&longs;er, <lb/>to re&longs;i&longs;t the pre&longs;&longs;ure of the Air; and part<lb/>ly by &longs;ome of the <emph type="italics"/>Phænomena<emph.end type="italics"/> of our Ex-<pb pagenum="246"/>periments, and particularly by this Cir<lb/>cum&longs;tance of the three and Thirtieth, <lb/>that the Sucker was by the pre&longs;&longs;ure of the <lb/>Ambient Air impell'd upwards, with its <lb/>weight hanging at it, not only when it <lb/>was at the bottome of the Cylinder, and <lb/>con&longs;equently left a great <emph type="italics"/>Vacuum<emph.end type="italics"/> in the <lb/>cavity of it; but when the Sucker had <lb/>been already impel'd almo&longs;t to the top of <lb/>the Cylinder, and con&longs;equently, when the <lb/><emph type="italics"/>Vacuum<emph.end type="italics"/> that remain'd was become very <lb/>litle in compari&longs;on of that which preceded <lb/>the beginning of the Sucker's a&longs;cention. </s>

<s>In the next place, the&longs;e Experiments <lb/>may teach us, what to judge of the vul<lb/>gar Axiom receiv'd for &longs;o many Ages <lb/>as an undoubted Truth in the Peripate<lb/>tick Schools; That Nature abhorres <lb/>and flys a <emph type="italics"/>Vacuum,<emph.end type="italics"/> and that to &longs;uch a de<lb/>gree, that no humane power (to go no <lb/>higher) is able to make one in the Uni<lb/>ver&longs;e; wherein Heaven and Earth would <lb/>change places, and all its other Bodyes <lb/>rather act contrary to their own Nature, <lb/>than &longs;uffer it. </s>

<s>For, if by a <emph type="italics"/>Vacuum<emph.end type="italics"/> we <lb/>will under&longs;tand a place perfectly devoid <lb/>of all corporeal Sub&longs;tance, it may be in<lb/>deed then, as we formerly noted be plau<lb/>&longs;ibly enough maintain'd, that there is <pb pagenum="247"/>no &longs;uch thing in the world; but that the <lb/>generality of the Pleni&longs;ts, (e&longs;pecially till <lb/>of late yeares &longs;ome of them grew more <lb/>wary) did not take a <emph type="italics"/>Vacuum<emph.end type="italics"/> in &longs;o &longs;trict <lb/>a Sen&longs;e, may appear by the Experiments <lb/>formerly, and ev'n to this Day imploy'd <lb/>by the Deniers of a Vacuum, to prove it <lb/>impo&longs;&longs;ible that there can be any made. <lb/>For when they alleadge (for In&longs;tance) <lb/>that when a man &longs;ucks Water through a <lb/>long Pipe, that heavy Liquor, contrary <lb/>to its Nature, a&longs;cends into the Sucker's <lb/>mouth, only, to fill up that room made <lb/>by the Dilatation of his Bre&longs;t and <lb/>Lungs, which otherwi&longs;e will in part be <lb/>empty. </s>

<s>For when they alleadge (for In&longs;tance) <lb/>that when a man &longs;ucks Water through a <lb/>long Pipe, that heavy Liquor, contrary <lb/>to its Nature, a&longs;cends into the Sucker's <lb/>mouth, only, to fill up that room made <lb/>by the Dilatation of his Bre&longs;t and <lb/>Lungs, which otherwi&longs;e will in part be <lb/>empty. </s>

<s>And when they tell us, that the <lb/>rea&longs;on why if a long Pipe exactly <lb/>clos'd at one end be fill'd top-ful <lb/>of Water, and then inverted, no Liquor <lb/>will fall out of the open Orifice; Or, to <lb/>u&longs;e a more familiar Example, when they <lb/>teach, that the cau&longs;e why in a Gardiner's <lb/>watering Pot &longs;hap'd conically, or like a <lb/>Sugar-Loaf fill'd with Water, no Liquor <lb/>fals down through the numerous holes <lb/>at the bottome, whil&longs;t the Gardiner keeps <lb/>his Thumb upon the Orifice of the litle <lb/>hole at the top, and no longer, mu&longs;t be <lb/>that it in the ca&longs;e propo&longs;ed the Water <pb pagenum="248"/>&longs;hould de&longs;cend, the Air being unable to <lb/>&longs;ucceed it, there would be left at the up<lb/>per and de&longs;erted part of the Ve&longs;&longs;el a <emph type="italics"/>Va<lb/>cuum,<emph.end type="italics"/> that would be avoided if the hole <lb/>at the top were open'd. </s>

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<s>I &longs;aid, <pb pagenum="257"/>even in our Climate, becau&longs;e that is tem<lb/><arrow.to.target n="marg42"></arrow.to.target><lb/>perate enough; and as far as my ob&longs;er<lb/>vations a&longs;&longs;i&longs;t me to conjecture, the Air in <lb/>many other more Northern Countries <lb/>may be much thicker, and able to &longs;upport <lb/>a greater weight: which is not to be <lb/>doubted of, if there be no mi&longs;take in <lb/>what is Recorded concerning the <emph type="italics"/>Hollan<lb/>ders,<emph.end type="italics"/> that were forc'd by the Ice to Win<lb/>ter in <emph type="italics"/>Nova Zembla,<emph.end type="italics"/> namely, That <lb/>they found there &longs;o conden&longs;'d an Air, that <lb/>they could not make their Clock goe, <lb/>ev'n by a very great addition to the <lb/>weights that were wont to move it. </s>

<s><margin.target id="marg42"></margin.target><emph type="italics"/>Aere &longs;rig<gap/><lb/>do exi&longs;tcate <lb/>tardius mo<lb/><gap/>entur Au<lb/>tomat a <expan abbr="quã">quam</expan> <lb/>acre ca<gap/>ida, <lb/>adco qui<lb/>dem ut Au<lb/>tomaton <lb/>quod Delgæ <lb/>in Nova <lb/>Zembla a<lb/>gentes in æ<lb/>dibus &longs;u<gap/>s <lb/>collocave<lb/>runt, omal<lb/>no à motis <lb/>ce&longs;&longs;ave<gap/>it <lb/><gap/>t&longs;i m<gap/><lb/>malus toa<lb/>dus ei addidi&longs;&longs;ent quam antea ferre &longs;olebat.<emph.end type="italics"/> Varenius Geo: Genevat <gap/>. <lb/>111. Propo: 7. pag. </s>

<s>111. Propo: 7. pag. </s>

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<s>But afterwards, <lb/>the Bubbles (as had been apprehended) <lb/>began to di&longs;clo&longs;e them&longs;elves in the Wa<lb/>ter, and a&longs;cending to the top of the <emph type="italics"/>Si<lb/>phon,<emph.end type="italics"/> imbodyed them&longs;elves there into <lb/>one, which was augmented little by little <lb/>by the ri&longs;ing of other bubbles that from <lb/>time to time broke into it, but much <pb pagenum="278"/>fir&longs;t we thought might be &longs;ome &longs;tain up<lb/>on the Gla&longs;s; but after, finding it to <lb/>be in divers Qualities like the Oyl, <lb/>and Salt of the Concrete we were Di<lb/>&longs;tilling, we began to &longs;u&longs;pect that the <lb/>mo&longs;t &longs;ubtle and fugitive parts of the im<lb/>petuou&longs;ly a&longs;cending Steams, had pene<lb/>trated the &longs;ub&longs;tance (as they &longs;peak) of <lb/>the Gla&longs;s, and by the cold of the am<lb/>bient Air were conden&longs;'d on the &longs;ur<lb/>face of it. </s>

<s>And though we were ve<lb/>ry backward to credit this &longs;u&longs;pition, and <lb/>therefore call'd in an Ingenious Per&longs;on <lb/>or two, both to a&longs;&longs;i&longs;t us in the Ob<lb/>&longs;ervation, and have Witne&longs;s of its e<lb/>vent, we continued a while longer to <lb/>watch the e&longs;cape of &longs;uch unctuous Fumes, <lb/>and upon the whole matter unanimou&longs;ly <lb/>concluded, That all things con&longs;ider'd, <lb/>the &longs;ubtle parts of the di&longs;till'd matter <lb/>being violently agitated, by the exce&longs;<lb/>&longs;ive heat had pa&longs;&longs;'d through the Pores <lb/>of the Gla&longs;s, widen'd by the &longs;ame heat. <lb/>But this having never happen'd but <lb/>once in any of the Di&longs;tillations we have <lb/>either made or &longs;een, though the&longs;e be <lb/>not a few, it is much more rea&longs;onable <lb/>to &longs;uppo&longs;e, that the perviou&longs;ne&longs;s of <lb/>our Receiver to a Body much more <pb pagenum="279"/>&longs;ubtle then Air, proceeded partly from <lb/>the loo&longs;er Texture of that particular <lb/>parcel of Gla&longs;s the Receiver was made <lb/>of (for Experience has taught us, that <lb/>all Gla&longs;s is not of the &longs;ame compact<lb/>ne&longs;s and &longs;olidity) and partly from the <lb/>enormous heat, which, together with <lb/>the vehement agitation of the pene<lb/>trant Spirits, open'd the Pores of the <lb/>Gla&longs;s; then to imagine that &longs;uch a <lb/>&longs;ub&longs;tance as Air, &longs;hould be able to per<lb/>meate the Body of Gla&longs;s contrary to <lb/>the te&longs;timony of a thou&longs;and Chymical <lb/>and Mechanical Experiments, and of <lb/>many of tho&longs;e made in our Engine, e<lb/>&longs;pecially that newly recited: Nay, by <lb/>our fifth Experiment it appears, that <lb/>a thin Bladder will not at its Pores <lb/>give pa&longs;&longs;age even to rarified Air. </s>

<s>But this having never happen'd but <lb/>once in any of the Di&longs;tillations we have <lb/>either made or &longs;een, though the&longs;e be <lb/>not a few, it is much more rea&longs;onable <lb/>to &longs;uppo&longs;e, that the perviou&longs;ne&longs;s of <lb/>our Receiver to a Body much more <pb pagenum="279"/>&longs;ubtle then Air, proceeded partly from <lb/>the loo&longs;er Texture of that particular <lb/>parcel of Gla&longs;s the Receiver was made <lb/>of (for Experience has taught us, that <lb/>all Gla&longs;s is not of the &longs;ame compact<lb/>ne&longs;s and &longs;olidity) and partly from the <lb/>enormous heat, which, together with <lb/>the vehement agitation of the pene<lb/>trant Spirits, open'd the Pores of the <lb/>Gla&longs;s; then to imagine that &longs;uch a <lb/>&longs;ub&longs;tance as Air, &longs;hould be able to per<lb/>meate the Body of Gla&longs;s contrary to <lb/>the te&longs;timony of a thou&longs;and Chymical <lb/>and Mechanical Experiments, and of <lb/>many of tho&longs;e made in our Engine, e<lb/>&longs;pecially that newly recited: Nay, by <lb/>our fifth Experiment it appears, that <lb/>a thin Bladder will not at its Pores <lb/>give pa&longs;&longs;age even to rarified Air. </s>

<s>And <lb/>on this occa&longs;ion we will annex an Ex<lb/>periment, which has made &longs;ome of <lb/>tho&longs;e we have acquainted with it, <lb/>doubt, whether the Corpu&longs;cles of the <lb/>Air be not le&longs;&longs;e &longs;ubtle then tho&longs;e of <lb/>Water. </s>

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<s>And on this occa&longs;ion I remember, that <lb/>whereas it appears by our fifth Experi<lb/>ment, That the Aërial Corpu&longs;cles (ex<lb/>cept perhaps &longs;ome that are extraordinari<lb/>ly fine) will not pa&longs;&longs;e thorow the Pores <lb/>of a Lambs Bladder, yet Particles of Wa<lb/>ter will, as we have long &longs;ince ob&longs;erv'd, <lb/>and as may be ea&longs;ily try'd, by very clo&longs;e<lb/>ly tying a little <emph type="italics"/>Alcalizate<emph.end type="italics"/> Salt (we u&longs;'d <lb/>the Calx of Tartar, made with Nitre) <lb/>in a fine Bladder, and dipping the lower <lb/>end of the Bladder in Water; for if you <lb/>hold it there for a competent while, you <lb/>will finde that there will &longs;train thorow the <lb/>Pores of the Bladder Water enough to <lb/>di&longs;&longs;olve the Salt into a Liquor. </s>

<s>But I &longs;ee I am &longs;lipt into a Digre&longs;&longs;ion, <lb/>wherefore I will not examine, whether, <lb/>the Experiment I have related, proceed<lb/>ed from hence, That the &longs;pringy Texture <lb/>of the Corpu&longs;cles of the Air, makes <lb/>them le&longs;s apt to yield and accommodate <lb/>them&longs;elves ea&longs;ily to the narrow Pores of <lb/>Bodies, then the more flexible Particles <lb/>of Water; or whether it may more pro<lb/>babiy be a&longs;crib'd to &longs;ome other Cau&longs;e. <lb/>Nor will I &longs;tay to con&longs;ider how far we may <lb/>hence be a&longs;&longs;i&longs;ted to ghe&longs;s at the cau&longs;e of <lb/>the a&longs;cen&longs;ion of Water in the &longs;lender <pb pagenum="283"/>Pipes and <emph type="italics"/>Siphons<emph.end type="italics"/> formerly mention'd, <lb/>but will return to our Bubble; and take <lb/>notice, That we thought fit al&longs;o to en<lb/>deavor to mea&longs;ure the capacity of the <lb/>Bubble we had made u&longs;e of, by filling <lb/>it with Water, that we might the better <lb/>know how much Water an&longs;wered in <lb/>weight to 3/4 of a Grain of Air, but not<lb/>with&longs;tanding all the diligence that was <lb/>u&longs;ed to pre&longs;erve &longs;o brittle a Ve&longs;&longs;el, it <lb/>broke before we could perfect what we <lb/>were about, and we were not then pro<lb/>vided of another Bubble fit for our <lb/>turn. </s>

<s>Nor will I &longs;tay to con&longs;ider how far we may <lb/>hence be a&longs;&longs;i&longs;ted to ghe&longs;s at the cau&longs;e of <lb/>the a&longs;cen&longs;ion of Water in the &longs;lender <pb pagenum="283"/>Pipes and <emph type="italics"/>Siphons<emph.end type="italics"/> formerly mention'd, <lb/>but will return to our Bubble; and take <lb/>notice, That we thought fit al&longs;o to en<lb/>deavor to mea&longs;ure the capacity of the <lb/>Bubble we had made u&longs;e of, by filling <lb/>it with Water, that we might the better <lb/>know how much Water an&longs;wered in <lb/>weight to 3/4 of a Grain of Air, but not<lb/>with&longs;tanding all the diligence that was <lb/>u&longs;ed to pre&longs;erve &longs;o brittle a Ve&longs;&longs;el, it <lb/>broke before we could perfect what we <lb/>were about, and we were not then pro<lb/>vided of another Bubble fit for our <lb/>turn. </s>

<s>The ha&longs;te I was in, My Lord, when I <lb/>&longs;ent away the la&longs;t Sheet, made me forget <lb/>to take notice to you of a Problem that <lb/>occurr'd to my thoughts, upon the oc<lb/>ca&longs;ion of the &longs;low breaking of the Gla&longs;s <lb/>Bubble in our evacuated Receiver. </s>

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<s>I remember I have taken notice that <lb/>probably the rea&longs;on why the included Air <lb/>did not break the hermetically &longs;eal'd Bub<lb/>bles that remain'd intire in our emptyed <lb/>Receiver, was, That the Air, being &longs;ome<lb/>what rarefied by the Flame imploy'd to <lb/>clo&longs;e the Gla&longs;s, its Spring, upon the re-<pb pagenum="285"/>ce&longs;s of the heat, grew weaker then before. <lb/>But though we reject not that ghe&longs;s, yet <lb/>it will not in the pre&longs;ent ca&longs;e &longs;erve the <lb/>turn, becau&longs;e that much &longs;maller Gla&longs;s <lb/>bubbles exactly clo&longs;'d, will, by the in<lb/>cluded Air (though agitated but by the <lb/>heat of a very moderate Fire) be made <lb/>to fly in pieces. </s>

<s>But though we reject not that ghe&longs;s, yet <lb/>it will not in the pre&longs;ent ca&longs;e &longs;erve the <lb/>turn, becau&longs;e that much &longs;maller Gla&longs;s <lb/>bubbles exactly clo&longs;'d, will, by the in<lb/>cluded Air (though agitated but by the <lb/>heat of a very moderate Fire) be made <lb/>to fly in pieces. </s>

<s>Whether we may be <lb/>a&longs;&longs;i&longs;ted to &longs;alve this Problem, by con&longs;i<lb/>dering that the heat does from within ve<lb/>hemently agitate the Corpu&longs;cles of the <lb/>Air, and adde its a&longs;&longs;i&longs;tance to the Spring <lb/>they had before, I &longs;hall not now examine: <lb/>&longs;ince I here but propo&longs;e a Problem, and <lb/>that chiefly that by this memorable Story <lb/>of <emph type="italics"/>Cabæus,<emph.end type="italics"/> notice may be taken of the <lb/>prodigious power of Rarefaction, which <lb/>hereby appears capable of performing <lb/>&longs;tranger things then any of our Experi<lb/>ments have hitherto a&longs;crib'd to it. </s>

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<s>And this <lb/>the rather, becau&longs;e (a great part of this <pb pagenum="286"/>letter &longs;uppo&longs;ing the gravity of the Aire) <lb/>it will not be impertinent to determine <lb/>more particularly then hitherto we have <lb/>done, what gravity we a&longs;cribe to it. </s>

<s>We tooke then an <emph type="italics"/>Æolipile<emph.end type="italics"/> made of <lb/>copper, weighing &longs;ix ounces, five drachms, <lb/>and eight and forty graines: this being <lb/>made as hot as we dur&longs;t make it, (for feare <lb/>of melting the mettle, or at lea&longs;t the So<lb/>dar) was removed from the fire and im<lb/>mediately &longs;topped with hard wax that no <lb/>Aire at all might get in at the little <lb/>hole wont to be left in <emph type="italics"/>Æolipiles<emph.end type="italics"/> for the <lb/>fumes to i&longs;&longs;ue out at: Then the <emph type="italics"/>Æolipile<emph.end type="italics"/><lb/>being &longs;uffer'd lea&longs;urely to coole was again <lb/>weighed together with the wax that &longs;topt <lb/>it, and was found to weigh (by rea&longs;on of <lb/>the additionall weight of the wax) &longs;ix <lb/>ounces, &longs;ixe drachmes, and 39 graines. <lb/>La&longs;tly, the wax being perforated without <lb/>taking any of it out of the Scale, the <lb/>externall Aire was &longs;uffered to ru&longs;h in <lb/>(which it did with &longs;ome noy&longs;e) and then <lb/>the <emph type="italics"/>Æolipile<emph.end type="italics"/> and wax, being againe <lb/>weighed amounted to &longs;ix ounces, &longs;ix <lb/>drachmes, and 50. graines. </s>

<s>La&longs;tly, the wax being perforated without <lb/>taking any of it out of the Scale, the <lb/>externall Aire was &longs;uffered to ru&longs;h in <lb/>(which it did with &longs;ome noy&longs;e) and then <lb/>the <emph type="italics"/>Æolipile<emph.end type="italics"/> and wax, being againe <lb/>weighed amounted to &longs;ix ounces, &longs;ix <lb/>drachmes, and 50. graines. </s>

<s>So that the <lb/><emph type="italics"/>Æolipile<emph.end type="italics"/> freed as farre as our fire could <lb/>free it, from it's Aire, weighed le&longs;&longs;e then <pb pagenum="287"/>it &longs;elfe when repleni&longs;hed with Air, full <lb/>eleven graines. </s>

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<s>But the way formerly propo&longs;ed of <lb/>weighing the Air by an Æ<emph type="italics"/>olipile,<emph.end type="italics"/> &longs;eemes <lb/>by great oddes more exact; and (as farre <lb/>as we could ghe&longs;&longs;e) &longs;eemed to agree well <lb/>enough with the experiment made in our <lb/>Receiver. </s>

<s>Wherefore it will be be&longs;t to <lb/>tru&longs;t our Æ<emph type="italics"/>olipile<emph.end type="italics"/> in the enquiry we are a<lb/>bout, and according to our ob&longs;ervations <lb/>the water it contained amounting to one <pb pagenum="290"/>and twenty ounces and an halfe, and as <lb/>much Air as was requi&longs;ite to fill it weigh<lb/>ing eleven graines, the proportion in gra<lb/>vity of Air to Water of the &longs;ame bulk <lb/>will be as one to 938. And though we <lb/>could not fill the Æ<emph type="italics"/>olipile<emph.end type="italics"/> with water, &longs;o <lb/>exactly as we would, yet in regard we <lb/>could not either as perfectly as we would, <lb/>drive the Air out of it by heat; we think <lb/>the proportion may well enough hold: <lb/>but tho&longs;e that are delighted with round <lb/>numbers (as the phra&longs;e is) will not be <lb/>much mi&longs;taken if they reckon water to be <lb/>neere a thou&longs;and times heavier than Air. <lb/>And (for further proof that we have made <lb/>the proportion betwixt the&longs;e two bodies <lb/>rather greater then le&longs;&longs;er then indeed it is; <lb/>and al&longs;o to confirme our former ob&longs;erva<lb/>tion of the weight of the Air) we will adde, <lb/>That, having another time put &longs;ome Wa<lb/>ter into the Æ<emph type="italics"/>olipile<emph.end type="italics"/> before we &longs;et it on <lb/>the fire, that the copious vapours of the <lb/>rarefied liquor might the better drive out <lb/>the Air, we found, upon try all carefully <lb/>made, that when the Æ<emph type="italics"/>olipile<emph.end type="italics"/> was refrige<lb/>rated, and the included vapours were by <lb/>the cold turned againe into water (which <lb/>could not have happen'd to the Air, that <lb/>the preceeding Steams expell'd) the Air, <pb pagenum="291"/>when it was let in, increa&longs;'d the weight of <lb/>the <emph type="italics"/>Æolipile<emph.end type="italics"/> as much as before, namely, <lb/>Eleven Grains; though there were alrea<lb/>dy in it twelve Drachmes and a half, be<lb/>&longs;ides a couple of Grains of Water, which <lb/>remain'd of that we had formerly put in<lb/>to it to drive out the Air. </s>

<s>And (for further proof that we have made <lb/>the proportion betwixt the&longs;e two bodies <lb/>rather greater then le&longs;&longs;er then indeed it is; <lb/>and al&longs;o to confirme our former ob&longs;erva<lb/>tion of the weight of the Air) we will adde, <lb/>That, having another time put &longs;ome Wa<lb/>ter into the Æ<emph type="italics"/>olipile<emph.end type="italics"/> before we &longs;et it on <lb/>the fire, that the copious vapours of the <lb/>rarefied liquor might the better drive out <lb/>the Air, we found, upon try all carefully <lb/>made, that when the Æ<emph type="italics"/>olipile<emph.end type="italics"/> was refrige<lb/>rated, and the included vapours were by <lb/>the cold turned againe into water (which <lb/>could not have happen'd to the Air, that <lb/>the preceeding Steams expell'd) the Air, <pb pagenum="291"/>when it was let in, increa&longs;'d the weight of <lb/>the <emph type="italics"/>Æolipile<emph.end type="italics"/> as much as before, namely, <lb/>Eleven Grains; though there were alrea<lb/>dy in it twelve Drachmes and a half, be<lb/>&longs;ides a couple of Grains of Water, which <lb/>remain'd of that we had formerly put in<lb/>to it to drive out the Air. </s>

<s><emph type="italics"/>Mer&longs;ennus<emph.end type="italics"/> indeed tells us, that by his <lb/>account Air is in weight to Water, as 1 to <lb/>1356. And adds, that we may, without <lb/>any danger, believe that the gravity of <lb/>Water to that of Air of a like bulk, is <lb/>not le&longs;s then of 1300 to 1. And con&longs;e<lb/>quently, that the quantity of Air to a <lb/>quantity of Water equiponderant there<lb/>to, is as 1300 to 1. But why we &longs;hould <lb/>relinqui&longs;h our own carefully repeated try<lb/>als, I &longs;ee not. </s>

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<s>Our Engine had not been long fini&longs;h'd, <lb/>when, at the fir&longs;t lea&longs;ure we could &longs;teal <lb/>from our occa&longs;ions to make tryal of it, <lb/>we cau&longs;'d the Air to be pump'd out of <lb/>the Receiver; and whil'&longs;t I was bu&longs;ied in <lb/>entertaining a Learned Friend that ju&longs;t <lb/>then came to vi&longs;it me, an Ingenious By-<pb pagenum="302"/>&longs;tander, thought he perceiv'd &longs;ome new <lb/>kind of Light in the Receiver, of which <lb/>giving me ha&longs;tily notice, my Friend and <lb/>I pre&longs;ently ob&longs;erv'd, that when the Suc<lb/>ker was drawn down, immediately upon <lb/>the turning of the Key, there appear'd <lb/>a kinde of Light in the Receiver, almo&longs;t <lb/>like a faint fla&longs;h of Lightening in the <lb/>Day-time, and almo&longs;t as &longs;uddenly did it <lb/>appear and vani&longs;h. </s>

<s>Having, not with<lb/>out &longs;ome amazement, ob&longs;erv'd divers <lb/>of the&longs;e Apparitions of Light, we took <lb/>notice that the Day was clear, the hour <lb/>about ten in the Morning, that the onely <lb/>Window in the Room fac'd the North; <lb/>and al&longs;o, that by interpo&longs;ing a Cloak, or <lb/>any opacous Body between the Receiver <lb/>and the Window, though the re&longs;t of the <lb/>Room were &longs;ufficiently enlightned, yet <lb/>the fla&longs;hes did not appear as before, un<lb/>le&longs;s the opacous Body were remov'd. <lb/>But not being able on all the&longs;e Circum<lb/>&longs;tances to ground any firm Conjecture <lb/>at the cau&longs;e of this &longs;urpri&longs;ing <emph type="italics"/>Phænome<lb/>non,<emph.end type="italics"/> as &longs;oon as Night was come, we <lb/>made the Room very dark; and plying <lb/>the Pump, as in the Morning, we could <lb/>not, though we often try'd, find, upon <lb/>the turning of the Key, &longs;o much as the <pb pagenum="303"/>lea&longs;t glimmering of Light; whence we <lb/>inferr'd, that the fla&longs;h appearing in the <lb/>Receiver, did not proceed from any new <lb/>Light generated there, but from &longs;ome <lb/>reflections of the light of the Sun, or <lb/>other Luminous Bodies plac'd without <lb/>it; though whence that Reflection <lb/>&longs;hould proceed, it po&longs;'d us to conje<lb/>cture. </s>

<s>But not being able on all the&longs;e Circum<lb/>&longs;tances to ground any firm Conjecture <lb/>at the cau&longs;e of this &longs;urpri&longs;ing <emph type="italics"/>Phænome<lb/>non,<emph.end type="italics"/> as &longs;oon as Night was come, we <lb/>made the Room very dark; and plying <lb/>the Pump, as in the Morning, we could <lb/>not, though we often try'd, find, upon <lb/>the turning of the Key, &longs;o much as the <pb pagenum="303"/>lea&longs;t glimmering of Light; whence we <lb/>inferr'd, that the fla&longs;h appearing in the <lb/>Receiver, did not proceed from any new <lb/>Light generated there, but from &longs;ome <lb/>reflections of the light of the Sun, or <lb/>other Luminous Bodies plac'd without <lb/>it; though whence that Reflection <lb/>&longs;hould proceed, it po&longs;'d us to conje<lb/>cture. </s>

<s>Wherefore the next Morning, ho<lb/>ping to inform our &longs;elves better, we <lb/>went about to repeat the Experiment, <lb/>but though we could as well as former<lb/>ly exhau&longs;t the Receiver, though the <lb/>place wherein we made the tryal was the <lb/>very &longs;ame; and though other Circum<lb/>&longs;tances were re&longs;embling, yet we could <lb/>not di&longs;cover the lea&longs;t appearance of <lb/>Light all that Day, nor on divers o<lb/>thers on which tryal was again fruitle&longs;<lb/>ly made; nor can we to this very time <lb/>be &longs;ure a Day before hand that the&longs;e <lb/>Fla&longs;hes will be to be &longs;een in our great <lb/>Receiver. </s>

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<s>And we particularly remember, <lb/>that, being at &longs;ome di&longs;tance from <emph type="italics"/>London<emph.end type="italics"/><lb/>one Night, that the People, upon a very <lb/>well-come Occa&longs;ion, te&longs;tified their Joy <lb/>by numerous Bon-fires; though, by rea<lb/>&longs;on of the Interpo&longs;ition of the Hou&longs;es, <lb/>we could not &longs;ee the Fires them&longs;elves, yet <lb/>we could plainly &longs;ee the Air all enlighten'd <lb/>over and near the City; which argu'd, <lb/>that the lucid Beams &longs;hot upwards from <lb/>the Fires, met in the Air with Corpu&longs;cles <lb/>opacous enough to reflect them to our <lb/>Eyes. </s>

<s>A third thing that we con&longs;idered, was, <lb/>That white may be produc'd (without <lb/>excluding other ways, or denying invi&longs;i<lb/>ble Pores in the &longs;olide&longs;t Bodies) when <lb/>the continuity of a Diaphanous Body <lb/>happens to be interrupted by a great num<lb/>ber of Surfaces, which, like &longs;o many <lb/>little Looking-gla&longs;&longs;es, do confu&longs;edly re<lb/>pre&longs;ent a multitude of little and &longs;eeming<lb/>ly contiguous Images of the elucid Body. <lb/>We &longs;hall not in&longs;i&longs;t on the explanation of <lb/>this, but refer You for it to what we have <pb pagenum="310"/>&longs;aid in another Paper (touching Co<lb/>lours.) But the In&longs;tances that &longs;eem to <lb/>prove it are obvious: For Water or whites <lb/>of Eggs beaten to froth, do lo&longs;e their <lb/>tran&longs;parency and appear white. </s>

<s>We &longs;hall not in&longs;i&longs;t on the explanation of <lb/>this, but refer You for it to what we have <pb pagenum="310"/>&longs;aid in another Paper (touching Co<lb/>lours.) But the In&longs;tances that &longs;eem to <lb/>prove it are obvious: For Water or whites <lb/>of Eggs beaten to froth, do lo&longs;e their <lb/>tran&longs;parency and appear white. </s>

<s>And ha<lb/>ving out of one of our le&longs;&longs;er Receivers <lb/>carefully drawn out the Air, and &longs;o order'd <lb/>it, that the hole by which the Water was <lb/>to get in, was exceeding &longs;mall, that the <lb/>Liquor might be the more broken in its <lb/>pa&longs;&longs;age thorow it, we ob&longs;erv'd with plea<lb/>&longs;ure, That, the Neck being held under <lb/>Water, and the little hole newly men<lb/>tion'd being open'd, the Water that ru&longs;h'd <lb/>in was &longs;o broken, and acquired &longs;uch a mul<lb/>titude of new Surfaces, that the Receiver <lb/>&longs;eem'd to be full rather of Milk then Wa<lb/>ter. </s>

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<s>But <lb/>however, by that time the Receiver <lb/>had been con&longs;iderably exhau&longs;ted, which <lb/>was done in le&longs;&longs;e then 1/4 of an hour, <lb/>we perceived the Water near the bot<lb/>tom of the Gla&longs;s Cylinder to Freeze, <lb/>and the Ice by a little longer &longs;tay, &longs;eem'd <lb/>to encrea&longs;e, and to ri&longs;e &longs;omewhat higher <pb pagenum="320"/>then the &longs;urface of the &longs;urrounding Li<lb/>quor, where into almo&longs;t all the Snow and <lb/>Salt were re&longs;olv'd. </s>

<s>The Gla&longs;s being ta<lb/>ken out, it appear'd that the Ice was as <lb/>thick as the in&longs;ide of the Gla&longs;s it fill'd, <lb/>though into that I could put my Thumb. <lb/>The upper &longs;urface of the Ice was very <lb/>concave, which whether it were due to <lb/>any unheeded accident, or to the ex&longs;u<lb/>ction of the Air, we leave to be deter<lb/>min'd by further tryal. </s>

<s>The Gla&longs;s being ta<lb/>ken out, it appear'd that the Ice was as <lb/>thick as the in&longs;ide of the Gla&longs;s it fill'd, <lb/>though into that I could put my Thumb. <lb/></s>

<s>The upper &longs;urface of the Ice was very <lb/>concave, which whether it were due to <lb/>any unheeded accident, or to the ex&longs;u<lb/>ction of the Air, we leave to be deter<lb/>min'd by further tryal. </s>

<s>And la&longs;tly, the <lb/>Ice held again&longs;t the Light, appear'd not <lb/>de&longs;titute of Bubbles, though &longs;ome By<lb/>&longs;tanders thought they were fewer then <lb/>would have been found if the Water had <lb/>been frozen in the open Air. </s>

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<s>I <lb/>know, My Lord, that to &longs;olve this Pro<lb/>blem, it will be &longs;aid, That Congelation <lb/>does not (as is commonly, but erroneou&longs;ly <lb/>pre&longs;um'd) reduce water into le&longs;s room <lb/>then it po&longs;&longs;e&longs;&longs;'d before, but rather makes <lb/>it take up more. </s>

<s>And I have el&longs;ewhere <lb/>prov'd by particular Experiments, That <lb/>whether or no Ice may be truly &longs;aid to be <lb/>Water rarefi'd (for that &longs;eems que&longs;tion<lb/>able) it may be &longs;aid to take up more room <lb/>then the Water did before Glaciation. <lb/>But though we grant that freezing makes <lb/>Water &longs;well, yet, how Cold (which in <lb/>Weather-Gla&longs;&longs;es manife&longs;tly condences <lb/>the Air) &longs;hould expand either the Water, <lb/>or the intercepted Air &longs;o forcibly, as to <lb/>perform &longs;uch things as we have newly re<lb/>lated, will yet remain a Problem. </s>

<s>But though we grant that freezing makes <lb/>Water &longs;well, yet, how Cold (which in <lb/>Weather-Gla&longs;&longs;es manife&longs;tly condences <lb/>the Air) &longs;hould expand either the Water, <lb/>or the intercepted Air &longs;o forcibly, as to <lb/>perform &longs;uch things as we have newly re<lb/>lated, will yet remain a Problem. </s>

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<s>So that <lb/>if no <emph type="italics"/>Vacuum<emph.end type="italics"/> be to be admitted, this Ex<lb/>periment &longs;eems to invite us to allow a <lb/>great di&longs;parity, either as to bulk, or as to <pb pagenum="326"/>agitation, or as to both, betwixt &longs;ome <lb/>parts of the Etherial Sub&longs;tance, and tho&longs;e <lb/>that are wont here below to produce Heat <lb/>and Fire. </s>

<s>We try'd al&longs;o what Operation the <lb/>drawing out of the Air would have upon <lb/>Camphire, that being a Body, which, <lb/>though not a Liquor, con&longs;i&longs;ts of &longs;uch <lb/>Volatile or Fugitive parts, that without <lb/>any greater agitation then that of the open <lb/>Air it &longs;elf, they will copiou&longs;ly flie away. <lb/>But we found not that even this loo&longs;e <lb/>Body was &longs;en&longs;ibly alter'd by the Ex&longs;ucti<lb/>on of the ambient Air. </s>

<s>But we found not that even this loo&longs;e <lb/>Body was &longs;en&longs;ibly alter'd by the Ex&longs;ucti<lb/>on of the ambient Air. </s>

<s>IT may &longs;eem well worth trying, whether <lb/><arrow.to.target n="marg54"></arrow.to.target><lb/>or no in our exhau&longs;ted Gla&longs;s the want <lb/>of an ambient Body, of the wonted thic<lb/>ne&longs;s of Air, would di&longs;able even light and <lb/>little Animals, as Bees, and other winged <lb/>In&longs;ects, to flie. </s>

<s>But though we ea&longs;ily <lb/>fore&longs;aw how difficult it would be to make <lb/>&longs;uch an Experiment; yet not to omit our <lb/>endeavors, we procur'd a large Fle&longs;h-fly, <lb/>which we convey'd into a &longs;mall Receiver. <lb/>We al&longs;o another time &longs;hut into a great <lb/>Receiver a Humming Bee, that appear'd <lb/>&longs;trong and lively, though we had rather <pb pagenum="327"/>have made the tryal with a Butter-fly, if <lb/>the cold Sea&longs;on would have permitted us <lb/>to finde any. The Fly, af<lb/>ter &longs;ome Ex&longs;uctions of the <lb/>Air, dropp'd down from the <lb/>&longs;ide of the Gla&longs;s whereon &longs;he <lb/>was walking: But, that the <lb/>Experiment with the Bee <lb/>might be the more in&longs;tructive, <lb/>we convey'd in with her a bun<lb/>dle of Flowers, which re<lb/>main'd &longs;u&longs;pended by a &longs;tring <lb/>near the upper part of the Receiver: And <lb/>having provok'd the Bee, we excited her <lb/>to flie up and down the capacity of the <lb/>Ve&longs;&longs;el, till at length, as we de&longs;ir'd, &longs;he <lb/>lighted upon the Flowers; whereupon <lb/>we pre&longs;ently began to draw out the Air, <lb/>and ob&longs;erv'd, That though for &longs;ome time <lb/>the Bee &longs;eem'd to take no notice of it, yet <lb/>within awhile after &longs;he did not flie, but fall <lb/>down from rhe Flowers, without appear<lb/>ing to make any u&longs;e of her Wings to help <lb/>her &longs;elf. </s>

<s>We al&longs;o another time &longs;hut into a great <lb/>Receiver a Humming Bee, that appear'd <lb/>&longs;trong and lively, though we had rather <pb pagenum="327"/>have made the tryal with a Butter-fly, if <lb/>the cold Sea&longs;on would have permitted us <lb/>to finde any. The Fly, af<lb/>ter &longs;ome Ex&longs;uctions of the <lb/>Air, dropp'd down from the <lb/>&longs;ide of the Gla&longs;s whereon &longs;he <lb/>was walking: But, that the <lb/>Experiment with the Bee <lb/>might be the more in&longs;tructive, <lb/>we convey'd in with her a bun<lb/>dle of Flowers, which re<lb/>main'd &longs;u&longs;pended by a &longs;tring <lb/>near the upper part of the Receiver: And <lb/>having provok'd the Bee, we excited her <lb/>to flie up and down the capacity of the <lb/>Ve&longs;&longs;el, till at length, as we de&longs;ir'd, &longs;he <lb/>lighted upon the Flowers; whereupon <lb/>we pre&longs;ently began to draw out the Air, <lb/>and ob&longs;erv'd, That though for &longs;ome time <lb/>the Bee &longs;eem'd to take no notice of it, yet <lb/>within awhile after &longs;he did not flie, but fall <lb/>down from rhe Flowers, without appear<lb/>ing to make any u&longs;e of her Wings to help <lb/>her &longs;elf. </s>

<s>But whether this fall of the Bee, <lb/>and the other In&longs;ect, proceeded from the <lb/>mediums being too thin for them to flie in, <lb/>or barely from the weakne&longs;s, and as it were <lb/>&longs;wooning of the Animals them&longs;elves, you <lb/>will ea&longs;ily gather from the following Ex<lb/>periment. </s><pb pagenum="328"/>

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<s><margin.target id="marg55"></margin.target><emph type="italics"/>Experi<lb/>ment<emph.end type="italics"/> 41.</s>

<s>A while after we put in a Mou&longs;e, new<lb/>ly taken, in &longs;uch a Trap as had rather af<lb/>frighted then hurt him; vvhil'&longs;t he vvas <lb/>leaping up very high in the Receiver, vve <lb/>fa&longs;ten'd the Cover to it, expecting that <lb/>an Animal u&longs;ed to live in narrow holes <lb/>vvith very little fre&longs;h Air, vvould endure <lb/>the vvant of it better then the lately men<lb/>tion'd Birds: But though, for a vvhile af<lb/>ter the Pump vvas &longs;et avvork, he conti<lb/>nued leaping up as before; yet 'tvvas not <lb/>long ere he began to appear &longs;ick and gid<lb/>dy, and to &longs;tagger, after vvhich he fell <lb/>dovvn as dead, but vvithout &longs;uch violent <lb/>Convul&longs;ions as the Birds died vvith. <lb/>Whereupon, ha&longs;tily turning the Key, we <lb/>let in &longs;ome fre&longs;h Air upon him, by vvhich <lb/>he recovered, after a vvhile, his &longs;en&longs;es and <lb/>his feet, but &longs;eem'd to continue vveak and <lb/>&longs;ick: But at length, grovving able to <lb/>skip as formerly, the Pump vvas plyed <lb/>again for eight minutes, about the mid<lb/>dle of vvhich &longs;pace, if not before, a very <lb/>little Air by a mi&longs;chance got in at the <lb/>Stop-cock; and about tvvo minutes after <lb/>that, the Mou&longs;e divers times leap'd up <pb pagenum="331"/>lively enough, though after about two mi<lb/>nutes more he fell down quite dead, yet <lb/>with Convul&longs;ions far milder then tho&longs;e <lb/>wherewith the two Birds expired. </s>

<s>Whereupon, ha&longs;tily turning the Key, we <lb/>let in &longs;ome fre&longs;h Air upon him, by vvhich <lb/>he recovered, after a vvhile, his &longs;en&longs;es and <lb/>his feet, but &longs;eem'd to continue vveak and <lb/>&longs;ick: But at length, grovving able to <lb/>skip as formerly, the Pump vvas plyed <lb/>again for eight minutes, about the mid<lb/>dle of vvhich &longs;pace, if not before, a very <lb/>little Air by a mi&longs;chance got in at the <lb/>Stop-cock; and about tvvo minutes after <lb/>that, the Mou&longs;e divers times leap'd up <pb pagenum="331"/>lively enough, though after about two mi<lb/>nutes more he fell down quite dead, yet <lb/>with Convul&longs;ions far milder then tho&longs;e <lb/>wherewith the two Birds expired. </s>

<s>This <lb/>alacrity &longs;o little before his death, and his <lb/>not dying &longs;ooner then at the end of the <lb/>eighth minute, &longs;eem'd a&longs;cribable to the <lb/>Air (how little &longs;oever) that &longs;lipt into the <lb/>Receiver. </s>

<s>For the fir&longs;t time, tho&longs;e Con<lb/>vul&longs;ions (that, if they had not been &longs;ud<lb/>denly remedied, had immediately di&longs;<lb/>patch'd him) &longs;ei&longs;'d on him in &longs;ix minutes <lb/>after the Pump began to be &longs;et awork. <lb/>The&longs;e Experiments &longs;eem'd the more <lb/>&longs;trange, in regard, that during a great part of <lb/>tho&longs;e few minutes the Engine could but <lb/>con&longs;iderably rarefie the Air (and that too, <lb/>but by degrees) and at the end of them <lb/>there remain'd in the Receiver no incon<lb/>&longs;iderable quantity; as may appear by what <lb/>we have formerly &longs;aid of our not being <lb/>able to draw down Water in a Tube, with<lb/>in much le&longs;s then a Foot of the bottom: <lb/>with which we likewi&longs;e con&longs;ider'd, that by <lb/>the ex&longs;uction of the Air and inter&longs;per<lb/>&longs;ed Vapors, there was left in the Recei<lb/>ver a &longs;pace &longs;ome hundreds of times ex<lb/>ceeding the bigne&longs;s of the Animal, <gap/>e<lb/>ceive the fuliginous Steams, from which, <pb pagenum="332"/>expiration di&longs;charges the Lungs; and, <lb/>which in the other ca&longs;es hitherto known, <lb/>may be &longs;u&longs;pected, for want of room, to <lb/>&longs;tifle tho&longs;e Animals that are clo&longs;ely pent <lb/>up in too narrow Receptacles. </s>

<s>The&longs;e Experiments &longs;eem'd the more <lb/>&longs;trange, in regard, that during a great part of <lb/>tho&longs;e few minutes the Engine could but <lb/>con&longs;iderably rarefie the Air (and that too, <lb/>but by degrees) and at the end of them <lb/>there remain'd in the Receiver no incon<lb/>&longs;iderable quantity; as may appear by what <lb/>we have formerly &longs;aid of our not being <lb/>able to draw down Water in a Tube, with<lb/>in much le&longs;s then a Foot of the bottom: <lb/>with which we likewi&longs;e con&longs;ider'd, that by <lb/>the ex&longs;uction of the Air and inter&longs;per<lb/>&longs;ed Vapors, there was left in the Recei<lb/>ver a &longs;pace &longs;ome hundreds of times ex<lb/>ceeding the bigne&longs;s of the Animal, <gap/>e<lb/>ceive the fuliginous Steams, from which, <pb pagenum="332"/>expiration di&longs;charges the Lungs; and, <lb/>which in the other ca&longs;es hitherto known, <lb/>may be &longs;u&longs;pected, for want of room, to <lb/>&longs;tifle tho&longs;e Animals that are clo&longs;ely pent <lb/>up in too narrow Receptacles. </s>

<s>I forgot to mention, that having cau&longs;'d <lb/>the&longs;e three Creatures to be open'd, I <lb/>could, in &longs;uch &longs;mall Bodies, di&longs;cover lit<lb/>tle of what we &longs;ought for, and what we <lb/>might po&longs;&longs;ibly have found in larger Ani<lb/>mals; for though the Lungs of the Birds <lb/>appear'd very red, and as it were inflam'd, <lb/>yet that colour being u&longs;ual enough in the <lb/>Lungs of &longs;uch winged Creatures, de&longs;erves <lb/>not &longs;o much our notice, as it does, That <lb/>in almo&longs;t all the de&longs;tructive Experiments <lb/>made in our Engine, the Animals appear'd <lb/>to die with violently Convul&longs;ive Moti<lb/>ons: From which, whether Phy&longs;icians can <lb/>gather any thing towards the Di&longs;covery <lb/>of the Nature of Convul&longs;ive Di&longs;tem<lb/>pers, I leave to them to con&longs;ider. </s>

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<s><emph type="center"/><emph type="italics"/>A Digre&longs;sion containing &longs;ome <lb/>Doubts touching Re&longs;pi<lb/>ration.<emph.end type="italics"/><emph.end type="center"/></s>

<s>I Fear Your Lord&longs;hip will now expect, <lb/>that to the&longs;e Experiments I &longs;hould add <lb/>my Reflections on them, and attempt, <lb/>by their a&longs;&longs;i&longs;tance, to re&longs;olve the Diffi<lb/>culties that occur about Re&longs;piration; &longs;ince <lb/>at the beginning I acknowledg'd a further <lb/>Enquiry into the Nature of that, to have <lb/>been my De&longs;ign in the related Tryals. <lb/>But I have yet, becau&longs;e of the inconve<lb/>nient Sea&longs;on of the Year, made &longs;o few <lb/>Experiments, and have been &longs;o little &longs;a<lb/>tisfied by tho&longs;e I have been able to make, <lb/>that they have hitherto made Re&longs;piration <lb/>appear to me rather a more, then a le&longs;s <lb/>My&longs;terious thing, then it did before. </s>

<s>But I have yet, becau&longs;e of the inconve<lb/>nient Sea&longs;on of the Year, made &longs;o few <lb/>Experiments, and have been &longs;o little &longs;a<lb/>tisfied by tho&longs;e I have been able to make, <lb/>that they have hitherto made Re&longs;piration <lb/>appear to me rather a more, then a le&longs;s <lb/>My&longs;terious thing, then it did before. </s>

<s>But <lb/>yet, &longs;ince they have furni&longs;h'd me with <lb/>&longs;ome &longs;uch new Con&longs;iderations, concern<lb/>ing the u&longs;e of the Air, as confirms me in <lb/>my Diffidence of the Truth of what is <lb/>commonly believ'd touching that matter; <lb/>That I may not appear &longs;ullen or lazy, I <lb/>am content not to decline employing a <pb pagenum="336"/>few hours in &longs;etting down my Doubts, in <lb/>pre&longs;enting Your Lord&longs;hip &longs;ome Hints, <lb/>and in con&longs;idering whether the Tryals <lb/>made in our Engine, will at lea&longs;t a&longs;&longs;i&longs;t us <lb/>to di&longs;cover wherein the Deficiency lies <lb/>that needs to be &longs;upply'd. </s>

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<s>Nor &longs;hall we any further meddle with <lb/>tho&longs;e Controver&longs;ies &longs;o much agitated a<lb/>mong the Moderns, namely, <emph type="italics"/>Whether the <lb/>motion of the Lungs in Re&longs;piration be their<emph.end type="italics"/><pb pagenum="337"/><emph type="italics"/>own, or but con&longs;equent to the motion of the <lb/>Thorax, Diaphragme, and<emph.end type="italics"/> (as &longs;ome Learn<lb/>ed Men would have it) <emph type="italics"/>the Abdomen; And, <lb/>Whence it is that the Air &longs;wells the Lungs <lb/>in In&longs;piration<emph.end type="italics"/> any further then they may <lb/>receive light from our Engine: But that <lb/>it may appear what kinde of &longs;ervice it is <lb/>that may be expected from it on this oc<lb/>ca&longs;ion, we mu&longs;t premi&longs;e a few Words to <lb/>&longs;hew wherein the &longs;trength of the Obje<lb/>ction we are to an&longs;wer, lies. </s>

<s>In favor then <lb/>of tho&longs;e that would have the Lungs ra<lb/>ther pa&longs;&longs;ive then active in the bu&longs;ine&longs;s of <lb/>Re&longs;piration, it may again&longs;t the common <lb/>opinion be alledg'd, That as the Lungs be<lb/>ing de&longs;titute of Mu&longs;cles and of Fibres, <lb/>are unfit to dilate them&longs;elves; &longs;o it ap<lb/>pears, that without the motion of the <lb/><emph type="italics"/>Thorax<emph.end type="italics"/> they would not be fill'd with Air. <lb/>Since as our Learned Friend Dr. <emph type="italics"/>High<lb/>more<emph.end type="italics"/> has well (and congruou&longs;ly, to what <lb/>our &longs;elves have purpo&longs;ely try'd) ob<lb/>&longs;erv'd, if a live Dog have a great wound <lb/>made in his Che&longs;t, the Lobes of the <lb/>Lungs on that &longs;ide of the <emph type="italics"/>Media&longs;ti<lb/>num<emph.end type="italics"/> will &longs;ub&longs;ide and lie &longs;till; the <emph type="italics"/>Tho<lb/>rax<emph.end type="italics"/> and the Lobes on the other &longs;ide <lb/>of the <emph type="italics"/>Media&longs;tinum,<emph.end type="italics"/> continuing their <lb/>former motion. </s>

<s>Since as our Learned Friend Dr. <emph type="italics"/>High<lb/>more<emph.end type="italics"/> has well (and congruou&longs;ly, to what <lb/>our &longs;elves have purpo&longs;ely try'd) ob<lb/>&longs;erv'd, if a live Dog have a great wound <lb/>made in his Che&longs;t, the Lobes of the <lb/>Lungs on that &longs;ide of the <emph type="italics"/>Media&longs;ti<lb/>num<emph.end type="italics"/> will &longs;ub&longs;ide and lie &longs;till; the <emph type="italics"/>Tho<lb/>rax<emph.end type="italics"/> and the Lobes on the other &longs;ide <lb/>of the <emph type="italics"/>Media&longs;tinum,<emph.end type="italics"/> continuing their <lb/>former motion. </s>

<s>And if &longs;uddenly at once <pb pagenum="338"/>the Mu&longs;cles of the Che&longs;t be on both <lb/>&longs;ides di&longs;&longs;ected, upon the Ingre&longs;s of the <lb/>Air, the whole Lungs, though untouch'd, <lb/>will remain movele&longs;s, at lea&longs;t, as to any ex<lb/>pan&longs;ion or contraction of their &longs;ub&longs;tance. </s>

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<s>And this <pb pagenum="343"/>Conjecture, as it is &longs;pecious enough, &longs;o I <lb/>might have admitted it for true; but that <lb/>I con&longs;ider'd, that (not to mention that <lb/>one, e&longs;pecially of the Animals kill'd in <lb/>our Engine, &longs;eem'd manife&longs;tly for a pret<lb/>ty while, and not long before he dy'd, to <lb/>move his <emph type="italics"/>Thorax,<emph.end type="italics"/> as if he exerci&longs;'d Re&longs;pi<lb/>ration) the diligent <emph type="italics"/>Wallæus<emph.end type="italics"/> relates, That <lb/>he divers times ob&longs;erv'd, in the Di&longs;&longs;ecti<lb/>on of live Bodies, that the Membrane <lb/>that inve&longs;ts the Lungs, had Pores in it <lb/>as big as the larger &longs;ort of Peas, which a<lb/>grees with the Ob&longs;ervations of Chyrur<lb/>gions and Phy&longs;itians, <emph type="italics"/>viz.<emph.end type="italics"/> That matter <lb/>collected in the <emph type="italics"/>Thorax,<emph.end type="italics"/> has penetrated in<lb/>to the Lungs, and been di&longs;charged by <lb/>coughing. </s>

<s>And I remember too, that mo&longs;t <lb/>of the Animals we kill'd in our Engine <lb/>were Birds, of who&longs;e Lungs <emph type="italics"/>Harvey<emph.end type="italics"/><lb/>&longs;omewhere informs us, That he ob<lb/>&longs;erv'd them very manife&longs;tly to open at <lb/>their Extremities into the <emph type="italics"/>Abdomen.<emph.end type="italics"/><lb/>And by &longs;uch Perforations we may well <lb/>&longs;uppo&longs;e the pa&longs;&longs;age free betwixt the exter<lb/>nal Air and that in the <emph type="italics"/>Abdomen:<emph.end type="italics"/> But this <lb/>Conjecture may be further con&longs;ider'd. <lb/>Be&longs;ides, to &longs;how that the Animals that <lb/>died in our Gla&longs;&longs;es, need not be &longs;uppo&longs;'d <pb pagenum="344"/>to have been kill'd by the want of Air, we <lb/>fore&longs;ee another Argument that we mu&longs;t <lb/>deal &longs;o ingeniou&longs;ly with Your Lord&longs;hip, <lb/>as not to conceal. </s>

<s>Be&longs;ides, to &longs;how that the Animals that <lb/>died in our Gla&longs;&longs;es, need not be &longs;uppo&longs;'d <pb pagenum="344"/>to have been kill'd by the want of Air, we <lb/>fore&longs;ee another Argument that we mu&longs;t <lb/>deal &longs;o ingeniou&longs;ly with Your Lord&longs;hip, <lb/>as not to conceal. </s>

<s>You very well know, <lb/>that be&longs;ides the generality of the <lb/>Schools, there are many new Philo&longs;ophers <lb/>who, though they di&longs;&longs;ent from the old <lb/>Peripateticks in other things, do, as they, <lb/>deny the po&longs;&longs;ibility of a <emph type="italics"/>Vacuum;<emph.end type="italics"/> and <lb/>hold, that tho&longs;e &longs;paces which are devoid <lb/>of Air, and other gro&longs;&longs;er Bodies, are all <lb/>of them exactly repleni&longs;hed with a certain <lb/>Etherial Matter, &longs;o thin and &longs;ubtle, that <lb/>it can freely permeate the Pores of the <lb/>compacted&longs;t and clo&longs;e&longs;t Bodies, and ev'n <lb/>of Gla&longs;s it &longs;elf. </s>

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<s>Another &longs;u&longs;pition we &longs;hould have en<lb/>tertain'd concerning the death of our Ani<lb/>mals, namely, That upon the &longs;udden re<lb/>moval of the wonted pre&longs;&longs;ure of the am<lb/>bient Air, the warm Blood of tho&longs;e Ani<lb/>mals was brought to an Efferve&longs;cence or <lb/>Ebullition, or at lea&longs;t &longs;o vehemently ex<lb/>panded, as to di&longs;turb the Circulation of <lb/>the Blood, and &longs;o di&longs;order the whole Oe<lb/>conomy of the Body. (This (I &longs;ay) I <lb/>&longs;hould have had &longs;ome &longs;u&longs;pition of) but <lb/>that Animals of a hot Con&longs;titution are <lb/>not the &longs;ole ones that cannot in our ex<lb/>hau&longs;ted Engine exerci&longs;e the Function of <lb/>Life. </s>

<s>But I mu&longs;t not now dwell upon <lb/>matters of this nature, becau&longs;e I think <lb/>it high time to proceed to the con&longs;iderati-<pb pagenum="346"/>on of the principal &longs;ubject of our Engine, <lb/>namely, The u&longs;e of Re&longs;piration; or ra<lb/>ther, The u&longs;e of the Air in Re&longs;piration. <lb/>For whereas of the divers u&longs;es of it men<lb/>tion'd by Anatomi&longs;ts the mo&longs;t, &longs;uch as <lb/>the Production and Modulation of the <lb/>Voice by the Eli&longs;ion of the Air, the <emph type="italics"/>La<lb/>rynx<emph.end type="italics"/> &c. </s>

<s>For whereas of the divers u&longs;es of it men<lb/>tion'd by Anatomi&longs;ts the mo&longs;t, &longs;uch as <lb/>the Production and Modulation of the <lb/>Voice by the Eli&longs;ion of the Air, the <emph type="italics"/>La<lb/>rynx<emph.end type="italics"/> &c. </s>

<s>the expul&longs;ion of Excrements <lb/>by Coughing, the conveying in of Odours <lb/>by In&longs;piration, and &longs;ome others, rather <lb/>convenient for the well being of an Ani<lb/>mal, then ab&longs;olutely nece&longs;&longs;ary to his Life: <lb/>Whereas (I &longs;ay) the other u&longs;es are &longs;uch as <lb/>we have &longs;aid, The great <emph type="italics"/>Hippocrates<emph.end type="italics"/> him<lb/>&longs;elf gives this notable Te&longs;timony to the <lb/>u&longs;e of the Air, as to Animals endow'd <lb/>with Lungs, <emph type="italics"/>Mortalibus<emph.end type="italics"/> (&longs;ays he) <emph type="italics"/>hic<emph.end type="italics"/> (&longs;pi<lb/>ritus) <emph type="italics"/>tum vitæ, tum morborum ægrotis cau<lb/>&longs;a e&longs;t. </s>

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<s>But touching the account upon which <lb/>the In&longs;piration and Ex&longs;piration of Air <lb/>(both which are comprehended in <foreign lang="greek">a)gapno<gap/></foreign>, <lb/>Re&longs;piration) is &longs;o nece&longs;&longs;ary to Life, both <lb/>Naturali&longs;ts and Phy&longs;itians do &longs;o di&longs;agree, <lb/>that it will be very difficult either to re<lb/>concile their Opinions, or determine their <lb/>Controver&longs;ies. </s>

<s>For fir&longs;t, Many there are who think <lb/>the chief (if not &longs;ole) u&longs;e of Re&longs;piration <lb/>to be the Cooling and tempering of that <lb/>Heat in the Heart and Blood, which other<lb/>wi&longs;e would be immoderate: And this O<lb/>pinion, not onely &longs;eems to be mo&longs;t recei<lb/>ved among&longs;t Schola&longs;tick Writers, but di<lb/>vers of the new Philo&longs;ophers, Carte&longs;ians, <lb/>and others, admitted with &longs;ome variation; <lb/>teaching, That the Air is nece&longs;&longs;ary, by its <lb/>coldne&longs;s, to conden&longs;e the Blood that pa&longs;<lb/>&longs;es out of the right Ventricle of the <lb/>Heart into the Lungs, that thereby it may <lb/>obtain &longs;uch a con&longs;i&longs;tence, as is requi&longs;ite <lb/>to make it fit Fewel for the vital Fire or <lb/>Flame, in the left Ventricle of the heart. <lb/>And this Opinion &longs;eems favor'd by this, <lb/>That Fi&longs;hes, and other cold Creatures, <lb/>who&longs;e Hearts have but one cavity, are al-<pb pagenum="348"/>&longs;o unprovided of Lungs, and by &longs;ome o<lb/>ther con&longs;iderations. </s>

<s>And this Opinion &longs;eems favor'd by this, <lb/>That Fi&longs;hes, and other cold Creatures, <lb/>who&longs;e Hearts have but one cavity, are al-<pb pagenum="348"/>&longs;o unprovided of Lungs, and by &longs;ome o<lb/>ther con&longs;iderations. </s>

<s>But though it need <lb/>not be deny'd, that the in&longs;pir'd Air may <lb/>&longs;ometimes be of u&longs;e by refrigerating the <lb/>Heart; yet (again&longs;t the Opinion that makes <lb/>this Refrigeration, the mo&longs;t genuine and <lb/>con&longs;tant u&longs;e of the Air) it may be Obje<lb/>cted, That divers cold Creatures (&longs;ome <lb/>of which, as particularly Frogs, live in <lb/>the Water) have yet need of Re&longs;piration, <lb/>which &longs;eems not likely to be needed for <lb/>Refrigeration by them that are de&longs;titute of <lb/>any &longs;en&longs;ible heat, and be&longs;ides, live in the <lb/>cold Water: That even decrepid old <lb/>Men, who&longs;e natural heat is made very <lb/>languid, and almo&longs;t extingui&longs;h'd by rea<lb/>&longs;on of age, have yet a nece&longs;&longs;ity of fre<lb/>quent Re&longs;piration: That a temperate Air <lb/>is fitte&longs;t for the generality of breathing <lb/>Creatures; and as an Air too hot, &longs;o al<lb/>&longs;o an Air too cold, may be inconvenient <lb/>for them (e&longs;pecially, if they be troubled <lb/>with an immoderate degree of the &longs;ame <lb/>Quality which is predominant in the Air:) <lb/>That in &longs;ome Di&longs;ea&longs;es the natural heat is <lb/>&longs;o weaken'd, that in ca&longs;e the u&longs;e of Re&longs;pi<lb/>ration were to cool, it would be more <lb/>hurtful then beneficial to breath; and the <lb/>&longs;u&longs;pending of the Re&longs;piration, may &longs;up-<pb pagenum="349"/>ply the place of tho&longs;e very hot Medicines <lb/>that are wont to be employ'd in &longs;uch Di<lb/>&longs;tempers: That Nature might much bet<lb/>ter have given the Heart but a moderate <lb/>heat, then &longs;uch an exce&longs;&longs;ive one, as needs <lb/>to be perpetually cool'd, to keep it from <lb/>growing de&longs;tructive; which the gentle, <lb/>and not the burning heat of an Animals <lb/>Heart, &longs;eems not inten&longs;e enough &longs;o indi<lb/>&longs;pen&longs;ably to require. </s>

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