THE HISTORY OF 



[SECT. i. 



effected. It consisted of a boiler B, provided with a safety valve V ; and a cylinder 

 G H, connected to the boiler by a steam pipe S. The cylinder was closed at the 



FIG. 3. 



top, and contained a floating piston P ; and the base of the cylinder terminated in 

 a curved tube T, which ascended into a cylinder M ; the bent tube had a pipe Y, 

 from a reservoir of water communicating with it, and it was provided with a valve 

 at r. Now suppose the cylinder G H, to be filled with cold water by the pipe Y, 

 from the reservoir, and the boiler to contain strong steam ; by opening the cock E, 

 the steam would be admitted, and, pressing on the floating piston P, cause the 

 water to ascend into the cylinder M : its return is prevented by the valve K, and 

 the steam cock E being shut, and the cock R opened, to let the condensed steam 

 escape at the pipe R, the water from the reservoir refills the steam cylinder through 

 the pipe Y, and it is ready for repeating the operation. The water raised to be 

 directed to any useful object by the pipe D. 1 



A reference to the Marquis of Worcester's plan will show, that Papin did no 

 more than repeat his experiments. The scheme of adding to the effect by the 

 introduction of red hot irons into the cylinder G H, is too absurd to insert; but it is 

 in some measure redeemed by the suggestion, that the water raised by the engine 

 might be applied to drive a water wheel ; thus giving the idea of a steam engine 

 being applicable to impel machinery. 



9. In 1699, Mr. Amontons published a description of a machine, designed to 

 be moved by the spring of air when expanded by heat, and afterwards condensed 

 by contact with cold water. 2 The continual access of heated air to water would 



1 Belidor's Archi. Hydrau. ii. p. 328. 



2 Prony's Nouvelle Archi. Hydrau. ii. p. 89 (note), where it is described. 



