164 Whitehead and Hill — Measurement of Self- Inductance. 



lack of sensibility. Method 14, or more properly, the Obercleek 

 method, is without doubt the best method that we have for the 

 absolute measurement of self -inductance in terms of resistance. 

 It is easy to apply and if proper care be exercised results should 

 not differ from the mean by more than 2/10 per cent. Greater 

 accuracy than this is undoubtedly attainable and ought not to 

 be a matter of any great difficulty, for in the work here de- 

 scribed the frequency determination could have been improved 

 and the resistances much more accurately measured. Method 

 25 is better than the Rayleigh method as ordinarily used, is 

 very easy to work and has a very simple formula, involving 

 little calculation. Its accuracy is probably limited to about 

 one per cent. Method 3 for comparing self-inductance with 

 capacity is very sensitive and was found by Dr. Potts to be very 

 satisfactory. 



Johns Hopkins University, 

 Baltimore, Md. 



