STEAM AND GASOLINE ENGINES 



179 



within would be condensed to water and a vacuum would tend 

 to form. The pressure of the atmosphere on the disk would 

 then drive it back toward the closed end. But it remained 

 for an Englishman, Newcomen, to devise (1705) a means of 

 making practical application of this idea. 



Before this was 

 accomplished, how- 

 ever, Thomas Savery 

 devised a scheme for 

 pumping water by 

 the use of steam 

 (Fig. 69). A pipe 

 some 30 feet long 

 dipped into the water 

 at its lower end. At 

 its upper end was a 

 chamber that could 

 be cut off from the 

 pipe by a stopcock 

 and that also had a 

 vent pipe and a steam 



pipe both capable 

 of being closed by 

 stopcocks. Steam 

 was let into the 

 chamber, and the air 



FIG. 69. Diagram of Savery's improved steam 

 pumping engine. Steam generated in a flows into b 

 and fills it, after which the valve is closed and cold 

 water from pipe d pours over the outside of b. Thus 

 the steam condenses and water comes up through pipe 

 e, which extends down into well or mine and fills b. 

 Vessel c has been so filled, and now steam is entering 

 it, forcing the water up pipe/ toward the surface. 



let out while the cock 



to the water pipe was closed. When the chamber was full of 

 steam, vent pipes and steam pipes were closed by the cocks. 

 Then cold water was sprayed on the outside of the chamber until 

 the steam inside condensed making a vacuum. The cock in the 

 water pipe was then opened and the air pressure drove the water 

 up the pipe into the chamber, when the water-pipe cock was 

 closed and the vent pipe opened so the water could run out as 

 steam was let in. So the process started all over again. This 



