384 IRRIGATION FARMING. 



are expelled through the exhaust-pipe, which is con- 

 duc^led to the outer air. 



It has been found that the cost of a twenty horse- 

 power gasoline engine is about $1,450, and a thirty 

 horse-power about $2,000. The cost of running the 

 first will be about forty cents an hour, and the second 

 sixty cents. The amount of water raised will depend 

 upon the lift, the kind of pump used, and the general 

 arrangement of the plant. Assuming a lift of ten 

 feet, a twenty horse-power engine should lift about 

 five hundred inches, and a thirty horse-power about 

 seven hundred and fifty inches. For engines to raise 

 one or two inches continuous flow the expense would 

 be somewhat greater in proportion. The cost of oper- 

 ating these engines in localities where seventy-four 

 degree gasoline can be obtained in quantities at ten 

 cents a gallon, is one cent for each exerted horse- 

 power per minute. 



Hot-Air Engines. — These are construdled almost 

 wholly for pumping purposes, the motive power and 

 pumping apparatus being combined in one machine 

 inseparably connecfted in one frame. As its name im- 

 plies, the power is furnished by the heating of air, 

 which being forced into a cylinder when cold, expands 

 with the application of heat, and the alternate heating 

 and cooling of the air as it passes in and out of the 

 cylinders furnishes the motive power. The hot-air 

 engine is not adapted to heavy work, such as the 

 steam-engine. After fire has been applied for a short 

 time, and the air in the chamber has expanded, it is 

 necessary before the engine will start to turn the bal- 

 ance-wheel. This requires the strength of a man, but 



