WINDMILLS AND PUMPS. 257 



The chamber is bolted onto a frame which forms, 

 at one end, an entrance into the ram for the supply of 

 water, and connected at the other end with the outside, 

 or impetus valve. This frame also contains, placed at 

 right angles with the supply passage, outlets for the 

 water discharged to the reservoir. There is an opening 

 just above the supply-water passage into the air chamber 

 through its valve. The outside or impetus valve is so 

 arranged by bending upward the end of the supply pas- 

 sage that when it is closed by being forced or held up 

 against its seat no water can escape; and when it falls 

 clown of its own weight or is held down, the water can 

 flow freely from the ram. This is all there is to a hy- 

 draulic ram, and as there are but two valves to wear it 

 will last a lifetime. 



The operation, in forcing the water, is as simple as 

 the means. The water is brought to the ram through a 

 supply pipe laid on an incline. Through this the water 

 flows downward and out at the impetus valve until it 

 has acquired power, by its velocity, to throw the valve 

 up and close it. The momentum, or force of this fall- 

 ing stream of water continues, and it finds an outlet 

 through the valve in the air chamber, which opens. 

 The water continues to pour into the air chamber until 

 the pressure of the air is equal to that of the head of 

 water. This closes the air chamber valve and confines 

 the water which has been let in. At the same time the 

 impetus valve opens of its own weight, as the pressure 

 of the water in the supply pipe has been overcome by 

 the pressure of the air in the air chamber, and the water 

 commences to waste as before. While the water is wast- 

 ing at the impetus valve, the expansion of the air in the 

 air chamber forces the water out through the discharge 

 pipe. This operation will continue as long as the work- 

 ing parts keep in good condition and the water supply 

 lasts. 



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