THE HYDRAULIC RAM. 281 



In the vertical section (Fig. 81), AB is the descending 

 and FG the ascending column of water, which is sup- 

 plied from a reservoir at A. V is a valve opening down- 

 wards, and V is a valve opening upwards into the air- 

 vessel C ; H is a small auxiliary air-vessel with a valve K 

 opening inwards. 



The Action of the Machine. As the valve V at first 

 lies open by its own weight, a portion of the water, descend- 

 ing from A, flows through it ; but the upward flow of the 

 water towards the valve V increases the pressure tending to 

 lift the valve, and at last, if the valve is not too heavy, lifts 

 and closes it. The forward momentum of the column of 

 water ABD being destroyed by the stoppage of the flow, 

 the water exerts a pressure sufficient to open the valve V 

 and to flow through it into the air-vessel C, condensing the 

 air within; the reaction of the condensed air forces water 

 up the pipe FG. As the column of water ABD comes to 

 rest, the pressure of the water diminishes, and the valves 

 V and V both fall. The fall of the former produces a 

 rush of the water through the opening V, followed by an 

 increased flow down the supply pipe AB, the result of which 

 is again the closing of V, and a repetition of the process 

 just described, the water ascending higher in FG, and 

 finally flowing through G. 



The action of the machine is assisted by the air-vessel H 

 in two ways first, by the reaction of the air in H, which is 

 compressed by the descending water, and, secondly, by the 

 valve K, which affords supplies of fresh air. When the 

 water rises through V, the air in H suddenly expands, and 

 its pressure becoming less than that of the outer air, the 

 valve K opens, and- a supply flows in, which compensates 

 for the loss of the air absorbed by the water and taken up 

 the column FG, or wasted through V. About a third of 

 the water employed is wasted, but the machine once set in 

 motion will continue in action for a long time, provided the 



