FARM SANITATION 



495 



and suitable piping. As water is forced in at the bottom of 

 this tank, the air within is compressed, thus driving the 

 water from the tank to any part of the system. As the 

 effective capacity of the tank may be increased by having 

 an initial pressure of air within it, and as the water con- 

 tinually absorbs a part of the air, an air pump or a pump 

 to supply the air with the water must be provided. 



As the water is thoroughly protected by being tightly 

 inclosed, the tank may be placed where a freezing tempera- 

 ture is not reached. The cellar is the usual location. It 

 may, however, be buried in the ground, which has the advan- 

 tage that the water is kept at quite a uniform temperature 

 throughout the entire year. 



The air pressure tank for a water supply of small capacity 

 is very economical in first cost. Where the storage capacity is 

 large, however, the cost is so great as to be almost prohibitive. 

 A ten-barrel tank with a 

 water storage capacity of 

 six barrels will cost about 

 $00, and larger tanks a 

 correspondingly greater 

 amount. 



A more recent water- 

 supply system is known 

 as the Perry pneumatic 

 water-supply system. It 

 consists in a power-driven 

 air compressor, a storage 

 tank for the air under 



pressure, and an air- Fig. 306. A satisfactory method of install- 

 i . i . i ing exposed hydrants. 



driven water pump which 



pumps the water as required, maintaining a pressure upon 



the entire system. There is no storage of the water at all, 



Outer ceasin 

 vitt? screw c& 



Supply Pipe jjjjg 

 below frosf line , 



