WINDMILLS AXD PUMPS. 



550 



for the largest sized pump. Other forms of vacuum 

 pumps are the Pulsometer, Nye and Swan, the latter, 

 however, working by steam and 

 hot air combined, requiring high 

 pressure boilers and an air con- 

 denser, and making in all a 

 rather expensive plant. We are 

 not exactly satisfied thus far 

 with the operation of these vac- 

 uum pumps, and would rather 

 place dependence upon the du- 

 plex compound pumps with con- 

 densers. In these pumps the 

 steam works expansively, first 

 in the high pressure cylinders, 

 and then, by exhaust, into the FIG. 76. HIGH-LIFT VACUUM 

 opposite low pressure cylinders, PUMP. 



the high and low pressure cylinders being tandem on the 

 cylinder, and the condensers returning hot water to the 

 boiler and saving valuable fuel. 



Centrifugals. These pumps are worked by sta- 

 tionary engines and are quite generally used by sewer 



contractors. They are 

 good for low lifts, and 

 will throw sand and 

 gravel readily. On a 

 twenty-foot lift a No. 

 If Van Wie pump will 

 irrigate ten acres of 

 land and require a two 

 horse-power engine. A 



u * No. 2 pump will sup- 



FIG. 77. CENTRIFUGAL PUMP. p]y twenty acres re- 

 quiring three horse power. No. 3 pump, forty acres, 

 with six horse-power engine. No. 4 pump, eighty 

 acres, with ten horse-power engine. No. 6 pump, 160 



