70 



Dr. McLachlan on Elective Inductance, Effective 



capacity is fixed. There are two cases which arise : (a) the- 

 armature out of the housing, (b) the armature in the housing. 

 The measurement of the damping, i. e. the ratio of the 

 amplitude of the first positive to that of the first negative 

 oscillation, is conducted in the manner described in a former 

 paper *. It should be mentioned that both the wave form 

 and the separate frequencies of the two oscillations alter with 

 the added inductance. We are at the moment, however, only 

 interested in the above ratio. 



Fig. 18. — Showing the effect on the Peak Voltage and the Damping 

 of adding air-core inductance to the primary winding*. A. 

 current of 1 ampere broken by using a separate contact- 

 breaker. 



6000 



5750 



4250 



I 2 3 



Added Inductance (Millihenries). 

 Armature out ol housing, with core of stalloy sheets 0*38 mm. thick. 

 Current broken in primary == 1*0 ampere. 



Some experiments of the above nature resulted in the 

 curves of fig. 18. It is seen at once that not only do 

 * McLachlan, Proc. Phys. Soc. Feb. 1919. 



