tOL. XVI.] _ PHILOSOPHICAI- TKANSACTIONS. 34Q 



foot; I might make the wheel with the axis to make their revolution in one mi- 

 nute of time, and so order all things that the air under the ascending plugs 

 might come to be rarefied to such a degree, that by its elasticity it might not 

 counterpoise more than 7 feet of water, but at the same time the air in the recep- 

 tacles A A, B B, would even in its greatest dilatation be able to counterpoise 1 7 

 feet; so it is plain that the air will be driven from the receptacles into the pumps 

 by a strength equivalent to 10 feet of water; now if we compute after the method 

 published in the Transactions of the month of October last, what should be the 

 velocity of the air driven by such a pressure, we shall find that the said velocity 

 will be about 740 feet in a second ; so that in -^ minute, during which the 

 plug ascends, this air might pass above 2'2000 feet, although it were not 

 rarefied at all ; but being rarefied, as we suppose it to be, it might go a great 

 deal further. 



In great distances, there should be made as many pumps as receptacles, as X 

 had propounded in the first explication of my engine: and to raise water but 

 6o feet high, there should be required 13 or 14 receptacles, and as many 

 pumps. Some people may take this for a great difl[iculty. But I answer that 

 in this engine this is not so much as it seems at first; because the pressure 

 being all from without, there is no need of any great strength to resist it, and 

 so the metal for the pumps will cost but little. 



As for the third objection, wherein Mr. Nuis says that it does not appear how 

 the water in our engine may, by rarefaction, ascend higher than 32 feet. I 

 answer, that the water does not at any time ascend higher than from a lower re- 

 ceptacle into the next upper one, which is but I '2 feet high: so that it is plain 

 the pressure of the air may be sufficient to force it up. It is indifFere;it whe- 

 ther it be by rarefaction, or otherwise, that the water comes into the recepta- 

 cle; it is enough that the water is there, and that the air presses upon it with 

 such a strength, as will prevail against all that opposes it, as I have shown 

 above. 



To the fourth difficulty I answer: that although the use of the pipes be 

 merely for the conveying of air, they may nevertheless easily be filled with water 

 when need requires, and so the defects in them may as well be found out as in 

 the pipes that are used for the conveying of water. ^t 



An Answer of the same to the Author of the perpetual Motion. N° 186, p. 267. 

 I find, in the Nouvelles de la Republ. for December last, that the author 

 still persists to urge some new contrivances, which being added, he conceives 

 his engine must succeed. To this I answer, that I undertook only to show 

 that his first device would fail ; which I should scarcely have done, if I had 



