228 



GREENHOUSES 



electric motor. Usually, a hand pump of 

 large size is used, and power is applied by 

 means of a pumping jack. 



A very efficient but somewhat delicate 

 pumping device is the combined hot-air- 



and 



MANHOLE 



hi 



i 



ItV 



T 



f.i 



engine ana pump. 

 These pumps give 

 very good satisfac- 

 tion where the water 

 is reasonably close 

 to the surface, or 

 when it does not 

 have to be pumped 

 against too great a 

 pressure. Improved 

 types of large size 

 are now available, 

 and are very econ- 

 omical of fuel, but 

 the engine is not as 

 well adapted for 



general power pur- 

 Fig. 121. Diagram showing 



installation of an auto- pOSCS as are gas en- 

 pneumatic pump gines 



A form of pump, which is becoming quite 

 popular for domestic use is the auto-pneu- 

 matic pump. It is designed to be used in 

 an open well or a cased well of large bore, 

 as the pump proper is placed entirely be- 



