OP ARTS AND SCIENCES. 137 



Capacity. 



Mf. 



Line of No. 13 copper on 30 ft. poles (.0119 X 96 X 1.5) 1.71 

 Cable of No. 18 insulated with kerite to No. 10, .15 X 6 . .90 

 Switchboard 10 



Total capacity 2.71 



Product of total resistance by total capacity = 732 X 2.71 = 1984. 



If this line be reasonably free from extraneous noises, it will allow 

 of good business conversation with Blake transmitters. If, however, 

 it should be found to be a noisy line, we should have to return it 

 by means of a similar and parallel line, making a metallic circuit, 

 instead of through the earth. 



It is evident that, by using a cable of lower capacity and resistance, 

 we could have used a smaller pole wire, or, by choosing a larger pole 

 wire, we could have used a cable of greater resistance and capacity. 



It is also evident that our formula enables us to say which of 

 these alterations will give us the desired ease of conversation at the 

 minimum expense. 



