*0t MBLE ENGINEERING 2<) 



a stroke watch it work. When we start 



tlu- pump we must open the little pet cock between the 

 :/.ontal check valves. The globe valve must be 

 open so as to let the water in. A check valve, whether it 

 il or horizontal, will allow water to pass through 

 it one way only, if it is in good working order. If the 

 11 pass through both ways, it is of no account. 

 . the engine starts on the outward stroke and draws 

 lunger out of the chamber. This leaves a space in 

 the barrel which must be filled. Air cannot get into it, 

 because the pump is in perfect order, neither can the air 

 get to it through the hose, as it is in the water, so that 

 ir pressure on the surface of the water causes it to 

 up through the pipes, through the first check 

 and into the pump barrel. If the engine has a 12-inch 

 stroke, and the plunger is i inch in diameter, we h;. 

 colun in the pump 12 inches long and I 



in di 



The engine has now reached its outward stroke and 



starts back. The plunger comes back with it and takes 



the space occupied by tl which must get out of 



the way for the plunger. The water came up through the 



check valve. I nit it can's get back that way, as we 



ted. There is another live just ahead, 



and as the plunger travels back it drives the v. 



through this second check. When the plunger reaches 



