524 AGRICULTURAL ENGINEERING 



be between 1J^ and 2 cents per hour. Twenty 25-watt lamps 

 will furnish 400 candle-power. Thus the cost per candle- 

 power-hour might be at a minimum .00375 to .005 cents. As 

 the plant will seldom be operated at full capacity, the aver- 

 age cost will be much greater, perhaps double. 



Operation. The electric plant is not difficult to operate 

 by one who has some knowledge of electrical machinery. 

 The engine and the dynamo will not require a great amount of 

 attention. The storage must be supplied with electrolyte 

 from time to time. The battery is also the least durable part 

 of the entire plant. Perhaps a new set of electrodes for the 

 battery will be needed at the end of five years. A good engine 

 ought to last at least ten years. 



QUESTIONS 



1. What improvements have made the electric lighting plants 

 practical for farm homes? 



2. What are the advantages of electric light? 



3. Discuss the most serious objections to electric light. 



4. Is it generally practical to install an electric lighting plant large 

 enough for power service? 



5. Discuss the various sources of power for electric lighting plants. 



6. Define voltage. Amperage. 



7. What is a watt? A kilowatt? 



8. What is the relation between watts and candle power with tung- 

 sten lamps? 



9. What are the advantages of a low- voltage system? 



10. What are its disadvantages? 



11. Itemize the cost of an electric lighting plant. 



12. Discuss the cost of electric light. 



13. Discuss the care and maintenance of an electric lighting plant. 



