17: 



McCLELLAN— USE OF OSCILLOGRAPH. 



[April 14, 



To obtain it we have the following derivation : 



i\ _ _ sin ,5 sin (<p -f- 0) 

 t\ sin sin 



r = sin (f cot — cos <p, 



r 



cot = . cot cr, 



sin y 



. *. a = cot -1 I cot I + a> + d. 



\ sin v r ' / 



Before we can determine a, therefore, we have to determine 8 



(2) 



Fig. 5. 



The latter may be obtained by putting a non-inductive resistance 

 in place of L. This is shown in Fig. 5, from which as before 



3 = cot -1 I - ; - — cot if' I 4- a' 

 \ sin e' / 



(3) 



where 



r' = 



5MM 



To illustrate, and provide a test, arrangements were made as in 

 Fig. 6. An alternator which was under the control of the oper- 



