502 CONSTRUCTION, FARM ENGINEERING, MECHANICS 



Electric appliances on the farm. 



Many electrically-operated machines and devices are now on the 

 market. The list is being added to rapidly. The following tabulation 

 will give some idea of the development along these lines, aside from 

 electric lighting and house wiring : 



Device Horse-power 



Required 



Cream separator ^ to 4 



Milking machine 3 to 5 



Grindstone % 



Bottle-washer ^ 



Water-pump 1 to 10 



Shredder 10 to 15 



Silage-grinder 10 to 20 



Feed-grinder 5 to 10 



Threshing . ^. * 10 to 20 



Wood-saw . . 3 to 5 



Corn-sheller 1 to 4 



Hay-press 4 to 25 



Refrigerating K to 25 



The motor power of a stream (Rose). 



The power of a stream may be calculated by the following formula : 

 P = Awh, in which A is the number of cubic feet of water falling in one 

 second of time, w is the weight of a cubic foot of water, and h is the head 

 or height through which the water falls. To reduce this to horse- 

 power the formula should read : H.P. = , in which e represents 



550 



the efficiency, in percentage, of the type of wheel to be used. The effi- 

 ciencies of the various types of water-motors run about as follows : 



Per 

 Cent 



Undershot water-wheels 35 



Poucelet wheels 60 



Breast wheels 55 



High breast wheels 60 



Overshot wheels 68 



Pelton wheels 75 



Turbines 60-80 



Water-pressure engines 80 



Rams 60 



These values are only approximate, and may vary either way sev- 

 eral per cent. 



