450 



THE STEAM-ENGINE. 



factures, the motion of the piston was subject to more or less variation of 

 peed, and the quantity of steam admitted to the cylinder was subject to a 

 corresponding change. The quantity of steam, therefore, drawn into the con- 

 denser was subject to variation, and required a considerable change in the 

 quantity of cold water admitted through the jet to condense it. To regulate 

 this, the valve or cock by which the water was admitted into the condenser 

 was worked in the double-acting engine by a lever furnished with an index, 

 by which the quantity of condensing water admitted into the condenser could 

 be regulated. This index played upon a graduated arch, by which the engine- 

 man was enabled to regulate the supply. 



