152 



KEPORT — 1892. 



Two observations were made at a much lower temperature, and these 

 would seem to indicate a slightly less temperature-coefiBcient than is 

 shown by the observations between 10° C. and 20° C. 



The values of the two new coils in B.A. units between temperatures of 

 10° and 20° are given by 



J=l + -000260(^-14). 

 K=l + •000261(^-14-15). 



"We may thus conclude that during the past two years there has been 

 no relative change in the values of the platinum silver unit standards of 

 the Association. 



Four of these are the original standards made in 1865-67 ; two 

 others v^ere made by Messi-s. Elliott Bros, in 1885, and the last two by the 

 assistant at the Cavendish Laboratory from wire supplied by Messrs. 

 Elliott in 1889. 



APPENDIX VII. 



On the Standard Condensers of the Association, and on Certain Resistance 

 Coils. By R. T. Glazebrook, F.B S. ■ 



The report of the Committee for 1890 contains as an appendix a very 

 full account of the tests on the air condensers belonging to the Associa- 

 tion. It was there stated that while the insulation resistance of No. I. 

 was very high, that of No. II. was not completely satisfactory ; No. II. 

 was therefore taken to pieces and set up fresh. Its capacity and also that 

 of No. I. were determined afresh, using the commutator method described 

 in the previous paper. 



The following values wei^e found : — 



Table XII. 



Mean of the -whole, •021391 microfarad. 



The different values in each series correspond to different rates of 

 revolution of the commutator. 



