WINDMILLS AND PUMPS. 385 



after turning the wheel once around the engine can 

 take care of itself, and any child old enough to place 

 a shovelful of coal in the fire-box of a stove, and who 

 can be trusted to handle a fire can then operate the 

 engine an entire day. 



The cost of operating is small, and wood, coal, or 

 cobs can be utilized. A kerosene oil attachment is 

 always furnished. When oil is used the flow is self- 

 regulating, and after starting the engine it requires no 

 further attention for eight or ten hours. A special 

 pump is necessary, which is furnished with the engine. 

 The hot-air engine makes from 80 to 160 strokes a 

 minute, and its capacity ranges from a few gallons to 

 one- tenth of a second foot a minute, equivalent to two- 

 tenths of an acre foot a day of twenty-four hours, lim- 

 ited by the hight of lift which varies from a few yards 

 to 500 feet. The price of the hot-air engine, including 

 pump, etc. , is from $300 to $600, according to size of 

 cylinder, the former price being for a six-inch and the 

 latter for a ten-inch cylinder. As the six-inch cylinder 

 is as small as should be used for deep well pumping, 

 it is readily seen that the cost has prevented more 

 general introducftion of this device for pumping water 

 on the farms of the west. 



Compressed Air. — Modern science is ac5tively at 

 work endeavoring to employ air in raising water from 

 wells, and two or three feasible plans have already been 

 devised. One is the Chapman process, illustrated in 

 Fig. 90, which shows the apparatus as devised for a 

 well. By means of the proper machinery the injedled 

 air causes the well to flow. Air is forced down the 

 small pipe, comes up in a cone shape, filling the well- 



