HYDRAULICS. 433 



the cock b, and the valve a will fall down, and hinder 

 the water from being pushed out that way, by any force 

 that presses on its surface. All the internal part of the 

 vessel above b, will be full of common air, when the 

 water rises to b. 



Shut the cock c, and open the cocks d and e; then 

 pour as much water into the boiler JB (through the fun- 

 nel G) as will about half fill the boiler ; and then shut 

 the cock d, and leave the cock e open. 



This done, make a fire under the boiler E, and the 

 heat thereof will raise steam from the water in the 

 boiler ; and the steam will make its way thence, through 

 the pipe F, into the vessel A ; and the steam will com- 

 press the air (above b) with a very great force upon the 

 surface of the water in A. 



When the top of the vessel A feels very hot by the 

 steam under it, open the cock c in the pipe C ; and the 

 air being strongly compressed in A, between the steam 

 and the water therein, will drive all the water out of the 

 vessel A, up the pipe B C, from which it will fly up in 

 a jet to a very great height. In my fountain, which is 

 made in this manner, after Mr. Blakey's, three tea-cup- 

 fulls of water in the boiler will afford steam enough to 

 play a jet 30 feet high. 



When all the water is out of the vessel A, and the 

 compressed air begins to follow the jet, open the cocks 

 b and d to let the steam out of the boiler E and vessel 

 A, and shut the cock e to prevent any more steam from 

 getting into A ; and the air will rush into the vessel A 

 through the cock b, and the water through the valve a ; 

 and so the vessel will be filled up with water to the cock 

 b as before. Then shut the cock b and the cocks c and 

 </, and open the cock e ; and then, the next steam that 

 rises in the boiler will make its way into the vessel A 

 again ; and the operation will go on, as above. 



When all the water in the boiler E is evaporated, and 

 28. F f 



