178 



But the lag between the induced counter 

 electromotive force in the primary and 

 the secondary current was also 180°, 

 and therefore the phases of terminal 

 electromotive force, induced electromo- 

 tive force, and current in the primary, 

 must very nearly coincide, which was 

 only possible if there was practically no 

 self induction. He wished to offer an 

 explanation with regard to the units used 

 in the paper. His reason for adopting 

 these units was that they were convenient, 

 and since he first brought them forward 

 many others had adopted them. All 

 knew that the scientifically correct unit 

 was inconvenient for the shop, and as 

 the object of practical engineers was to 

 build machines in the easiest way, he had 

 adopted that system of units which many 

 years' practice had shown him to be the 

 most convenient. Professor Forbes had 

 objected to the parallel working of dyna- 

 mos, chiefly on the ground that it was 

 necessary to cut out certain districts in 

 case of fire. Mains might be joined in 

 parallel at the stations, but they need not 



