On a Development of Maxwell's Capacity Bridge. 1107 



we hope it may be possible to settle this question by 

 experiment *. 



It gives me great pleasure to express my best thanks to 

 Prof. M. Siegbahn of Lund and Prof. N. Bohr of Copenhagen, 

 for the great interest they have shown in my work. I am 

 also much indebted to my friend Mr. H. A. Kramers for his 

 valuable help in reading the manuscript. 



CXVI. On a Development of Maxwell's Capacity Bridge. 

 ByV. A. Bailey, M.A., The Queens College, Oxford f. 



TT is well known that one of the most accurate and con- 

 venient methods for determining Capacity in E.M. Units 

 is that devised by Clerk Maxwell, shown in fig. 1. 



Fiff. 1. 



reed. 



battery 

 res/'sta/7ce>. 



One side of the condenser is made to touch A nnd B 

 •alternately n times per second by means of an electrically- 

 driven tuning-fork or (as in the experiments of Thompson 

 and Searle) by means of a rotating commutator. The gal- 

 vanometer shows no deflexion when the following relation 

 holds : — 



p _ Q[( P + tQ(Q + R + Q) + Q(R + G)] 



nKj ~ [R(P + Q)+r(Q+R)][P<Q + R-i-ti) + QG] ' 



P, Q, R, and ? being the resistances of the conductors as 

 indicated in the diagram, and C the capacity of the condenser. 



* (Note added during- the proof.) — In this connexion attention maybe 

 ■called to a very interesting paper recently published by Mr. Wentzel 

 {Annalen der Physik, lxvi. p. 937 (1921)). In this paper Mr. Wentzel 

 -clearly showed that mobt of the non-diagram lines arise in an atom 

 •which has lost more than one electron. I intend to deal in particular 

 -with the non-diagram lines of the L-series in another paper. 



"f Communicated bv Prof. J. S. Townsend, F.R.S. 



4B 2 



