48 PHILOSOPHICAL TRANSACTIONS. [aNNO I672. 



CH, with a void space about it, as HD. For the issue of this experiment seems 

 very proper for determining this doubt; which therefore I am not willing to pre- 

 judge. There is yet another way of 'explaining the same hypothesis, without 

 allowing this subtile matter to pierce the glass, which is this: our common air 

 being an aggregate of very heterogeneous parts, we may well suppose some of 

 them to be springy, and others not to be so. The springy parts we may conceive 

 to be so many consistent bodies, like small hairs or springy threads, wrapped up 

 in different forms and variously entangled, and so as to form many vacuities capa- 

 ble of admitting some fluid matter, which may insinuate into those vacuities, as 

 water in a bundle of bushes, without disturbing the texture of those springy 

 'parts ; and which may press as a weight, but not as a spring. Now if in the Tor- 

 ricellian tube, there be a quantity of such springy matter, the spring hereof will 

 be of equal strength with that of external air, and therefore able to counter- 

 balance it, though its weight be much less, because admitted with such a tensure. 

 But if only an unspringy fluid, which presses only as a weight, not as a spring, 

 and this defended by the glass tube from any other pressure, save that of its own 

 weight ; it will still be too weak to force its own way, till its single weight be 

 equivalent to that with which it is to encounter ; which is, not only the springy 

 part of the air, but also that fluid unspringy part; which though it would give 

 way to a springy body pressing through it ; yet not to this fluid, like itself, and 

 destitute of such a spring; and is therefore able to keep it up to a much greater 

 height than it could do if uncleansed of springy air: so long at least as till some 

 springy body be admitted, or some concussion, equivalent to it, put it in motion ; 

 but being once in motion, it will so continue, as a bullet impelled by gunpowder, 

 or an arrow out of a bow, till stopped by some positive equiv^alent force. 



I do not deny, but that this explication may be subject to some difliculties 

 and exceptions ; but I think fewer than that of allowing the glass penetrable by 

 this subtile matter. But the best way to settle this business, being some suitable 

 experiments; I should recommend these, or some of these experiments, to 

 those of the Royal Society, who are in that kind better provided than I am. 



1 . That hinted by my Lord Brouncker, whether a large low tube, of less 

 height than the common standard, of about 29 inches English, or 27 inches 

 French, might be made to stand top-full of quicksilver, though a small hole be 

 left open at th^top; at least under water? I am apt to think, that it will rather 

 sink slowly and with a hifling noise, than fall suddenly and silently. 



2. Whether of two polished marbles, or metalline plates, the lower will be 

 found to stick to the upper, in the exhausted receiver, longer than is account- 

 able for from the ordinary counter- balance In the TorriceUian experiment. For 

 though M. Huygens now, and Mr. Boyle, have long since intimated this from 



