part of the neck of the Bottle that the shorter of the Pipes had its lower Orifice immerst beneath the surface of the Quick-silver and the longer Pipe reacht not quite so low as that Surface and so was immerst but in the Water by which contrivance we avoided the necessity of having two distinct vessels for our two stagnant Liquors which would have been inconvenient in regard of the slenderness of the upper part of our Receiver This done we conveyed the Bottle into a fitly shap'd Receiver formerly describ'd at the first Experiment and having begun to pump out the Air we took notice to what heights the Quick-silver and Water were impell'd up in their respective Tubes on which we had before made marks from inch to inch with hard Wax that they might not be remov'd by wet or rubbing and we observ'd that when the Quicksilver was impell'd up to two inches the Water was rais'd to about eight and twenty and when the Quick-silver was about one inch high the Water was about fourteen I say about partly because some allowances must be made for the sinking of the Superficies of the Stagnant Quicksilver and the greater subsidence of that of the stagnant Water by reason of the Liquors impell'd into the two Pipes partly because that the breadth of the Mark of wax was considerable when the Quick-silver was but about an inch high and so made it difficult to discern the exact height of the Metal when the water was fallen down to fourteen inches especially in regard that the Quick-silver never ascending so high as the neck of the Bottle which the water left far beneath it the thickness of the Receiver and that of so strong a Bottle made it difficult to discern so clearly the station of the Quick-silver as I could have wished EXPERIMENT XIV About the Heights answerable to their respective Gravities to which Mercury and Water will subside upon the withdrawing of the Spring of the Air. FOr the further illustration of the Doctrine propos'd in the last and some of the foregoing Experiments about the raising and sustentation of Liquors in Pipes by the Pressure of the Air I thought it not unfit to make the following Tryal though it were easie to foresee in this peculiar Experiment a peculiar difficulty We caus'd then to be convey'd into a fitly shap'd Receiver two Pipes of Glass very uneven in length but each of them seal'd at one end the shorter Tube was fill'd with Mercury and inverted into a small Glass Jarr wherein a sufficient quantity of that Liquor had been before lodg'd the longer Pipe was fill'd with common Water and inverted into a larger Glass wherein likewise a fit proportion of the same Liquor had been put Then the Receiver being closely cemented on to the Engine the Air was pump'd out for a pretty while before the Mercury began to subside but when it was so far withdrawn that its Pressure was no longer able to keep up a Mercurial Cylinder of that height that liquid Metal began to sink the Water in the other Tube though this were three times as long still retaining its full height But when the Quick-silver was fallen so low as to be but between three four inches above the surface of the Stagnant Quick-silver the Water also began to subside but sooner then according to the laws of meer Staticks it ought to have done because many Aerial Particles emerging from the body of the Water to the upper part of the Glass did by their Spring concurr with the Gravity of the water to depress this Liquor And so when the Quick-silver was three inches above the stagnant Mercury the water in the other Pipe was fallen divers inches beneath 42 and several inches beneath 28 when the Mercury had subsided an inch lower But this being no more then was to be expected after we had caus'd the Pumping to be a while continued to free the water the better from the latitant Air we let in the external Air and having thereby impell'd up again both the Liquors into their Pipes and remov'd the Receiver we took out those Pipes and inverting each of them again to let out the Air for even that wich held the Quick-silver had got a small Bubble though inconsiderable in comparison of the Air that had got up out of the Water we fill'd each of them with a little of the restagnant Liquor belonging to it and inverting each Tube once more into its proper liquor we repeated the Experiment and found it as it seem'd to require more pumping then before to make the Liquors begin to subside so that when the Mercury was fallen to three inches or two or one the water subsided so near to the heights of 42 28 or 14 inches that we saw no sufficient cause to hinder us from supposing that the litle differences that appear'd between the several heights of the Quick-silver and fourteen times as great heights of the Water which fell somewhat lower than its proportion in Gravity required proceeded from some Aerial Corpuscles yet remaining in spite of all we had done in the water and by their Spring though but faint when once they had emerg'd to the upper part of the Glass furthering a little the depression of it not now to mention lesser Circumstances particularly that the surface of the stagnant Water did not inconsiderably rise by the accession of the Water lately in the Pipe whereby the Cylinder of water rais'd above that surface became by so much the shorter However Your Lordship may if You think fit cause the Experiment to be reiterated which I could not so well do by reason of a mischance that befell the Receiver EXPERIMENT XV. About the greatest height to which Water can be rais'd by Attraction or Sucking Pumps SInce the making and the writing of the foregoing Experiments having met with an opportunity to borrow a place somewhat convenient to make a Tryal to what height Water may be rais'd by Pumping I thought not fit to neglect it For though both by the consideration of our Hypothesis to whose truth so many Phaenomena bear witness and though particularly by the Consequences deduceable from the three last recited Experiments I were kept from doubting what the event would be yet I thought it worth while to make the Tryal I know what is said to have been the Complaint of some Pump-makers But I confess the Phaenomenon 't was grounded on seem'd not to me to be certainly enough deliver'd by a Writer or two that mention what they complain'd of and their observation seems not to have been made determinately or carefully enough for a matter of this moment Since that which they complain of seems to have been in general that they could not by pumping raise Water to what height they please as the common Opinion of Philosophers about Natures fuga vacui made them expect they might And it may well have happen'd that as they endeavoured onely to raise it to the height their
to argue either that there was a vacuum in the cavity of the Syringe or else that if it were full of Aether that body vvas so subtle that the impulse it received from the falling Sucker vvould not make it displeace a very litle Thread perhaps not exceeding a Grain in Weight of Water that vvas in the slender Pipe though it appear'd by the bubbles that sometimes disclos'd themselves in the Water after the Receiver had been exhausted that far more Water vvould be displac'd and carried up by a small bubble consisting of such rarified Air that according to my Aestimate the Aerial particles of it did not before the Pump vvas begun to be set on vvork take up in the Water a five-hundredth part of the quantity of a Pins head But whilst we were considering what to do further in our Tryal a litle Air that strain'd in at some small undiscoverable Leak drove the Water into the emptied part of the Pipe and put an end for that time to our Tryal which had been too toylsome to invite us then to reiterate it I had indeed thoughts of prosecuting the Enquiry by dropping from the top of the exhausted Receiver light Bodies conveniently shap'd to be turn'd round or otherwise put out of their simplest motion of Descent if they met with any resistance in their fall and by making such Bodies move Horizontally and otherwise in the Receiver as vvould probably discover whither they were assisted by the medium and other contrivances and wayes I had in my thoughts whereby to prosecute our Enquiry but vvanting time for other Experiments I could not spare so much as was necessary to exhaust large Receivers so diligently as such nice Trials would exact and therefore I resolv'd to desist till I had more leisure than I then had or have since been Master of In the interim thus much we seem to have already discovered by our past Tryals that if when our Vessels are very diligently freed from Air they are full of Aether that Aether is such a body as will not be made sensibly to move a light Feather by such an impulse as would make the Air manifestly move it not onely whilst t is no thinner than common Air but when t is very highly rarified which if I mistake not it was in our Experiment so much as to be brought to take up above an hundred times more room than before And one thing more we gain'd by the Tryal made with water namely a clear confirmation of what I deliver'd in the 34 th Experiment about the cause of the Suction that is made by Syringes for Your Lordship may remember that at the close of the Experiment we have all this while been reciting I observ'd that when the external Air was so very well withdrawn the pulling up of the Sucker would not make the stagnant Water that the Pipe of the Syringe was immerst in to ascend one inch or so much as the tenth part of it EXPERIMENT XL. About the falling in the Exhausted Receiver of a light Body fitted to have its motion visibly varied by a small resistance of the Air. PArtly to try whether in the space deserted by the Air drawn out of our Receivers there would be any thing more fit to resist the motion of other light Bodies through it than in the former Experiment we found It to impell them into motion and partly for another purpose to be mention'd by and by we made the following Tryals We took a Receiver which though less tall than we would have had was the longest we could procure and that we might be able not so properly to let down as to let fall a Body in it we so fastned a small pair of Tobacco-Tongs to the inside of the Receivers Brass-Cover that by moving the Turning-key we might by a string tied to one part of them open the Tongs which else their own Spring would keep shut This being done the next thing was to provide a Body which vvould not fall down like a Stone or another dead Weight through the Air but would in the manner of its descent shew that its motion was somewhat resisted by the Air vvherefore that vve might have a Body that vvould be turn'd about Horizontally as it were in its fall we thought fit to joyn Cross-wise four broad and light Feathers each about an Inch long at their Quils with a litle Cement into vvhich vve also stuck perpendicularly a small Label of Paper about an 8 th of an inch in breadth and somewhat more in height by vvhich the Tongues might take hold of our light Instrument vvithout touching the Cement which else might stick to them By the help of this small piece of Paper the litle Instrument of vvhich it made a part vvas so taken hold of by the Tongs that it hung as Horizontal as such a thing could well be plac'd and then the Receiver being cemented on to the Engine the Pump vvas diligently ply'd till it appear'd by a Gage which had been conveyed in that the Reciver had been carefully exhausted Lastly our eyes being attentively fix'd upon the connected Feathers the Tongs were by the help of the Turning-key open'd and the litle Instrument let fall which though in the Air it had made some turns in its descent from the same height it now fell from yet now it descended like a dead Weight without being perceiv'd by any of us to make so much as one Turn or a part of it notwithstanding which I did for greater security cause the Receiver to be taken off and put on again after the Feathers were taken hold of by the Tongs whence being let fall in the Receiver unexhausted they made some Turns in their descent as they also did being a second time let fall after the same manner But when after this the Feathers being plac'd as before we repeated the Experiment by carefully pumping out the Air neither I nor any of the By-standers could perceive any thing of Turning in the descent of the Feathers and yet for further security we let them fall twice more in the unexhausted Receiver and found them to turn in falling as before whereas when we did a 3 d time let them fall in the well exhausted Receiver they fell after the same manner as they had done formerly when the Air that vvould by its resistance have turn'd them round vvas remov'd out of their vvay Note 1. though as I intimated above the Glass vvherein this Experiment was made were nothing near so tall as I would have had it yet it was taller than any of our ordinary Receivers it being in height about 22 inches 2. One that had had more leisure and conveniency might have made a more commodious Instrument than that we made use of for being accidentally visited by that Sagacious Mathematician D r Wren and speaking to him of this matter he was pleas'd with great dexterity as well as readiness to make me a little Instrument of Paper on which
urge that t is affirm'd not onely by the generality of our Chymists but by learned modern Physitians that when either Glass of Antimony or Crocus metallorum impregnate Wine with Vomative and Purgative Particles they do it without any decrement of their weight because the Scales in Apothecaries Shops and the litle accurateness wont to be imployed in weighing things by those that are not vers'd in Statical affairs make me though not deny the Tradition which may perchance be true yet unwilling to build upon observations which to be relyed on are to be very nicely made and therefore I shall rather take notice that though the Loadstone be concluded to have constantly about it a great multitude of Magnetical Effluvia which may be call'd its Atmosphere yet it has not been observed to loose any thing of its Weight by the recess of so many Corpuscles But because if the Cartesian Hypothesis about Magnetisms be admitted the Argument drawn from this instance will not be so strong as it seems and as it otherwise would be I shall add a more unexceptionable Example for I know you will grant me that Odours are not diffus'd to a distance without Corporeal Emanations from the Odorous body and yet though good Amber-Greece be even without being excited by external heat constantly surrounded by a large Atmosphere you will in one of the following Discourses find cause to admire how inconsiderable the wast of it is If it be said that in Tract of time a Decrement of weight may appear in Bodies that in a few hours or dayes discovers not any the Objection if granted overthrows not our Doctrine it being sufficient to establish what we have been saying if we have evinc'd that the Effluvia of some Bodies may be subtle enough not to make the Body by their avolation appear lighter in Statical Trials that are not extraordinarily and as it were obstinately protracted And this very Objection puts me in mind to adde that for ought we know the Decrement of Bodies in Statical Experiments long continued may be somewhat Greater than even nice Scales discover to us for how are we sure that the weights themselves which are commonly made of Brass a Metal very unfixt may not in Tract of time suffer a litle Diminution of their Weight as well as the Bodies counterpois'd by them and no man has I think yet tryed whether Glass and even Gold may not in tract of time loose of their Weight which in case they should do it would not be easily discover'd unless we had Bodies that were perfectly fixt by comparison to which we might be better assisted than by comparing them with Brass weights or the like which being themselves less fixt will lose more than Gold and Glass My third and last consideration is that there may be divers other wayes besides those furnish'd us by Staticks of discovering the Effluvia of solid Bodies and consequently of shewing that t is not safe to conclude that because their Operation is not constant or manifest such Bodies do never emit any Effluvia at all and so are uncapable to work by their intervention on any other Body though never so well dispos'd to receive their Action And this I the rather desire that you would take notice of because my chief though not onely design in these Notes is you know to illustrate the Doctrine of occult Qualities and it may conduce to explicate several of them to know that some particular Bodies emit Effluvia though perhaps they do it not constantly and uniformly and though perchance too they do not appear to emit any at all if they be examin'd after the same manner with other exhaleable Bodies but onely may be made to emit them by some peculiar way of handling them or appear to have emitted them by some determinate operation on some other single Body or at most small number of Bodies Perchance you did not think till you read what I lately told you about Glass that from a Body that had endured so violent a fire there could by so sleight a way as rubbing a litle while one piece against another be obtain'd such steams as may not onely affect but offend the Nostrils Nor should we easily believe if Experience did not assure us of it that a Diamond that is justly reputed the hardest known Body in the World should by a litle rubbing be made to part with Electrical Effluvia Nay that I may give some kind of confirmation to that part of the last Paragraph that seems most to need it I shall adde that I once had a Diamond not much bigger than a large Pen which had never been polish'd or cut whose Electrical virtue was sometimes so easily excited that if I did but pass my fingers over it to wipe it the virtue would disclose it self and if as soon as I had taken it out of my Pocket I applied a hair to it though I touch'd not the Stone with my fingers that I might be sure not to rub it that Hair would be attracted at some distance and many times one after an other especially by one of the sides of the Stone whose surface was made up of several almost triangular Planes and though this excitation of the Diamond seemed to proceed onely from the warmth that it had acquir'd in my Pocket yet I did not find that That warmth though it seem'd not to be alter'd had alwaies the same effect on it though the wiping it with my finger fail'd not that I remember to excite it Something like this uncertainty I always observ'd in another Diamond of mine that was much nobler than the first and very well polished and in a small Ruby that I have yet by me which would sometimes be considerably Electrical without being rubb'd when I but wore the Ring it belong'd to on my litle finger and sometimes again it seem'd to have lost that virtue of operating without being excited by friction and that sometimes within a few minutes without my knowing whence so quick a change should proceed But I must insist no longer on such particulars of which I elsewhere say something and therefore I prceed to take notice that we should scarce have dream'd that when a Partridg or a hunted Deer has casually set a foot upon the ground that part where the Footstep hath been though invisibly impress'd should continue for many hours a Source of Corporeal Effluxes if there were not setting Dogs and Spaniels and Bloud-hounds whose noses can take notice at that distance of time of such Emanations though not onely other sorts of Animals but other sorts of Dogs are unable to do so I saw a stone in the hands of an Academick an Acquaintance of mine which I should by the Eye have judg'd to be an Agate not a Blood stone and consequently I should not have thought that it could have communicated Medicinal Effluvia appropriated to excessive Bleeding if the Wearer of it had not been subject to that Disease and had