THE MASTER WORKER 



tively high pressure, and that sometimes this pressure 

 becomes enormous. 



COMPOUND ENGINES 



As to the compound engine, that also, as has been 

 pointed out, was invented by a contemporary of Watt, 

 Jonathan Hornblower by name, whose patent bears 

 date of 1781. In Hornblower's engine, steam was 

 first admitted to a small cylinder, and then, after per- 

 forming its work on the piston, was allowed to escape, 

 not into a condensing receptacle, but into a larger 

 cylinder where it performed further work upon another 

 piston. This was obviously an instance of the use of 

 steam expansively, and it has been pointed out that, in 

 consequence, Hornblower was the first to make use 

 of this idea in practise, although it is said that Watt's 

 experiments had even at that time covered this field. 

 The application of the idea to the movement of the 

 second cylinder, however, appears to have been original 

 with Hornblower. Certainly it owed nothing to Watt, 

 who refused to accept the idea, and continued through- 

 out his life to frown upon the compound engine. 



Nevertheless, the device had great utility, as subse- 

 quent experiments were very fully to demonstrate. 

 The compound engine was revived by Woolf in 1804, 

 and his name rather than Hornblower 's is commonly 

 associated with it. The latter experimenter demon- 

 strated that the compound engine has two important 

 merits as against the simple engine. One of these is 

 that the sum of the two forces exerted by the joint ac- 

 tion results in a more even and continuous pressure 



