102 



THAT'S IT ; 



which is supported on the up- 

 right, 12, and moves upon the 

 axis, 14, works a pump by the 

 connecting chain, 16, and raises 

 water from mines — which was 

 the first application of the steam 

 engine. 



The water injected to cool the 

 steam in the cylinder, 2, is drawn 

 off through the pipe, 4, and 

 steam being again admitted, the 

 same actions are repeated as be- 



fore. This engine was far from 

 perfect, being slow in its opera- 

 tion, and requiring the constant 

 labour of an attendant to open 

 and shut the valve, 5, and the 

 stop-cocks. 



This was called the atmospheric engine, be- 

 cause it was worked chiefly by the pressure ol 

 the atmosphere, acting against the sudden con- 

 densation of steam. The steam was used to give 

 effect to the atmospheric pressure. In the true 

 steam engine, the steam forces the piston both 

 up and down, by beautiful mechanical con- 

 trivances. 



380. 



Another view of the toiler, 

 379, exhibits some recent im- 

 provements. This boiler is pro- 

 vided with a float, 1, which 

 regulates the supply of water, in 

 connection with the lever, 6, and 

 the weight, 7, the water being 

 supplied hot through the feed- 

 pipe*, 4 ; steam passes from the 

 boiler to the engine, 380, through 

 { the steam-pipe, 5 ; and the boiler 



is provided with gauge pipes, 2, 

 and a safety valve, 3. 



In the improved steam engine, 

 380, the steam is introduced to 

 the iron cylinder, 8, by its elastic 

 force, alternately above and below 

 the piston, 15, and forces the 

 piston up or down accordingly. 

 The steam used for this purpose 

 is of much higher pressure than 

 that employed in the atmospheric 



