i8o 



OUR PHYSICAL WORLD 



device worked slowly, for the chamber had to be heated by the 

 flow of steam for some time, else the steam would condense 

 as rapidly as it entered. The cocks were operated by hand by 

 an attendant. Savery later improved this by adding a second 

 chamber in order that while the steam was flowing into one it 

 could be condensing in the other. 



Newcomen built a vertical cylinder closed at its lower end 

 and connected at the same end with a steam pipe from the 



water -fcuik 

 cylinder 



valves 

 outlet pipe 



steam boiler 



FIG. 70. Diagram of Newcomen's engine 



boiler (see Fig. 70). In this pipe there was a valve. Three other 

 pipes also connected with this cylinder, each having a valve. 

 One of these connected with a water tank so cold water could be 

 sprayed into the cylinder, another was an outlet pipe for water, 

 and the third an outlet pipe for air. The disk was connected 

 by a chain to one end of a lever to the other end of which beyond 

 the fulcrum there was attached another chain that fastened to a 

 weight and to a pump. The attendant would open the air vent 



