378 IRRIGATION FARMING. 



and when it falls down of its own weight, or is held 

 down, the water can flow freely from the ram. This 

 is all there is to a hydraulic 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 fcjrce, 

 of this falling 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 wasting 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 working parts keep in good 

 condition and the water supply lasts. 



The supply must be from four to twelve feet higher 

 than the location of the ram, and from twelve to one 

 hundred and fifty feet distant from it. In locating a 

 ram, not only the fall and distance must be taken into 

 consideration, but some means of draining the waste 

 water from the ram must be provided. If the ram must 

 be located in a pit to get the desired fall, a drain must 



