212 



ELEMENTS OF GENEBAL SCIENCE 



in figure 104. In the following list of common devices for 

 the use of electricity there are also given the number of 

 watts and amperes consumed per hour and the approximate 

 cost per hour for each device. 



COST OF OPERATING HEATING DEVICES 



(Computed oil a cost basis of ten cents per kilowatt hour) 



DOMESTIC DEVICES 



COMMERCIAL DEVICES 



222. Electric advertising signs. The electric sign is one 

 of the wonders of modern life. Lamps are arranged so as 

 to spell the name of the article or firm advertised. Switches 



