ON STAKDARDS FOR USE IN ELECTRICAL MEASUREMENTS. 119 



The Committee regret that the insulation of some of the coils referred 

 to in their last Report, which had been selected for the new standards of 

 resistance, as defined by the resolutions adopted at Edinburgh, has proved 

 defective. Traces of acid have been discovered in the paraffin with which 

 the coils were filled. The two one-ohm standards of the Association,' 

 as well as two of the one-ohm standards of the Board of Trade,^ were 

 found in January last to have so low an insulation resistance between the 

 coil and the case as to be useless. 



Thus the labour spent in the testing of these coils has been wasted ; 

 much of it will need to be done again. The insulation of some of the 

 other standard ohm coils is not satisfactory. The single ohm standards 

 have therefore been remade, and the others are being refilled with carefully 

 selected paraffin. The original B.A. units have not, so far as comparisons 

 between them can show, changed their values during the year, and one 

 set of new ohm standards also has shown no sign of change. 



The Committee print, as an appendix to the Report, the report of the 

 proceedings at the International Congress at Chicago, presented to the 

 Secretary of State at Washington by the American delegate to the 

 Conference. 



During the j'ear Professor J. V. Jones has determined, by the aid of 

 his Lorenz apparatus, the absolute resistance of certain wire coils of 

 about -1 ohm. These have been compared with the standards of the 

 Association by the Secretary. An account of these experiments is con- 

 tained in Appendices II. and III. The resistance standards of the 

 Association have been compared with those of the Board of Trade by 

 Mr. Rennie and the Secretary. Details of this comparison will be found 

 in Appendix IV., while in Appendix V. is given, by Mr. E. O. Walker, 

 an account of a comparison between five coils belonging to the Indian 

 Government, which have been for twenty-four years in India, and Dr. 

 Muirhead's standards. Mr. Fitzpatrick has continued his work on the 

 specific resistance of copper, and has drawn up a table (see Appendix 

 VI.) reducing to the same units experimental results recently obtained 

 by various observers. Appendix VII. contains the Final Report of the 

 Electrical Standards Committee of the Board of Trade and the Order in 

 Council relating to Standards for Electrical Measurement. 



In consequence of the difficulty met with in the insulation of some of 

 the coils, it was thought well to defer the purchase of other coils for 

 which the grant of 25^. was obtained last year. The Committee are of 

 opinion that it is desirable to complete their set of standards by obtaining 

 from Germany certified copies of the standards of the Reichsanstalt. 

 They recommend, therefore, that they be reappointed, with the addition 

 of the name of Mr. Rennie, and with a grant of 251. ; that Professor G. 

 Carey Foster be Chairman and Mr. R. T. Glazebrook Secretary. 



APPENDIX I. 



Report of the Action of the International Electrical Congress held in 

 Chicago, August 1893, in the Matter of Units of Electrical Measxire. 



Washington, D.C. : Noremher 6, 1893. 

 The Hon. W. Q. Gresham, Secretary of State, Washington, D.C. 



Sir, — The undersigned, having been designated by you on May 12, 

 1893, as delegates to represent the United States in the International 

 ' lte])ort, 1893, p. 129. ^ /jj^^ 1392, p. 134. 



