376 IRRIGATION FARMING. 



because more runners are added as the depth is 

 increased. This compounding of the runners increases 

 the efficiency of the pump, for whatever number of 

 pounds pressure is exerted on the water by one runner 

 in lifting it at a given rate of speed is repeated by each 

 of the runners. For example, if one runner running 

 at a given rate of speed gives ten pounds pressure to a 

 square inch, then two runners would give twenty 

 pounds; three, thirty pounds, and so on. For this 

 reason water may be elevated higher above the dis- 

 charge with this pump than can be done with a centri- 

 fugal. These pumps are provided with ball-bearings 

 so arranged as to hold the shaft and runners suspended 

 in the well, and to carry the entire weight of all the 

 movable parts of the pump, . and also the entire 

 weight of the column of water, thereby making a 

 great saving of power. For extreme deep lifts, cone 

 roller-bearings are used in place of the ball-bearings. 

 One of these pumps in fourteen hours raised 1,190,000 

 gallons of water, 100 feet through a lo-inch casing 

 with a thirty horse-power engine. Another pump 

 raised 190 miner's inches 50 feet with twenty horse- 

 power. 



Hydraulic Rams. — These machines have been 

 very much improved of late years, and are now quite 

 extensively depended upon for domestic and irrigating 

 water-supply in the west and south. The principle 

 on which the hydraulic ram works is simple and easily 

 understood. A hydraulic ram consists of three parts — 

 two valves and an air-chamber. In Fig. 86 will be 

 seen the working parts of a ram exposed to view. / 

 is the air-chamber; P, delivery pipe; N, overflow; A, 



