FARM SANITATION 623 



the power unless required to do other work while running the 

 generator. If pumping, churning, and other forms of light 

 work are contemplated, a two-horsepower engine will usually 

 be found very satisfactory. The storage battery must con- 

 tain 56 cells, and if they are of the 20-ampere-hour size they 

 will furnish all of the lamps with current for four hours. 



Fig. 318. Engine, dynamo, storage battery, and switchboard of an elec- 

 tric lighting plant. 



The Cost of the Plant. The total cost of plant may be 

 estimated as follows: 



1 2-horsepower gasoline engine $125 



1 ^-kilowatt generator 60 



1 storage battery,, 20-ampere-hour, 56 cells at $2.50 140 



1 complete switchboard 75 



17 tungsten lamps 7 



12 carbon lamps 3 



Wiring 50 



Fixtures 30 



Total cost $490 



The Cost of Light. The cost of operating the plant will 

 be principally that of gasoline, which, at the usual price, will 



