NEW ENGINE. 175 



cut while putting in, before the gathering hand has collected 

 the stems together, and consequently many drop and are 

 lost; which is not the case with Mr. Hutton's new-invented 

 reep-hook, which does not cut before the stems are collected 

 together in the gathering hand. 



III. 



Report 0/ Messrs. De Prony, Charles, Montgolfikr, 

 and Carnot, to the French lusiitute, on the Invention of a 

 new Engine, by Mr» Cagniard-Latour, /ormer/y Pupil 

 at the Polytechnic School*, 







T is known, that all bodies immersed in a fluid lose a Principle o£ a 

 part of their weight equal to that of the fluid they displace, ^^^ engine. 

 On this principle Mr. Cagniard's new engine is founded. 



The first mover in this engine is not the vapour of boiling f<i„t nxover, 

 water, as in common steam engines, but a volume of air, 

 which, being conveyed cold to the bottom of a vessel full of 

 hot water, is there dilated ; and, by the effort it then makes 

 to rise to the surface, acts in the manner of a weight, but in 

 a vertical direction, agreeably to the principle mentioned 

 above. 



This mover, once discovered, may be employed in differ- 

 ent ways: the following is that of Mr. Cagniard. 



His machine, properly speaking, is composed of two The machine 

 others, which have perfectly distinct functions. The object compoicdof , 



of the first is to convey to the bottom of the vessel of hot * . 



11 /» 1 1 . rr^, /. 1 answenng diP- 



water the volume of cold air necessary. That of the se- ferent pur« 



cond, to apply the efibrt, which this air, once dilated by P***^^- 



heat, makes to reach the upper surface of the fluid, to the 



eff^ect required to be produced. 



For the first purpose Mr. Cagniard employs the screw ofThe first the 



Archimedes, If such a screw cause a fluid to ascend by ^^[j^gj^^'^" 



turning it in one direction ; it is obvious, that it will cause it 



te descend, if turned in the contrary direction. If then it 



• Journal d« Mines, vol. XXVI, p» 465. 





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