ON PRACTICAL STANDARDS FOR ELECTRICAL MEASUREMENTS. 39 



delegates were Professor W. Jaeger, Professor F. Laporte, and Mr. 

 F. E. Smith. 



Professor S. W. Stratton kindly offered the facilities of the Bureau 

 of Standards for the investigation, and, in his capacity as Treasurer of 

 the International Committee, was able to secure the funds to defray 

 expenses. Towards this object the governing bodies of the American 

 Institute of Electrical Engineers, the National Electric Light Asso- 

 ciation, the Association of Edison Illuminating Companies, and the 

 Illuminating Engineering Society most generously subscribed 100L 

 each. Some smaller contributions were also received. 



The primary object of the meeting was to determine the electro- 

 motive force of the Weston normal cell in terms of the international 

 units of resistance and current. At the same time it was necessary 

 to clear up certain outstanding problems on the standard cell and the 

 silver voltameter. Previous to the meeting a great deal of experimental 

 work had been done at each of the four institutions, and the results 

 obtained were compared before deciding on a programme of experi- 

 mental work. 



The European delegates took with them from their own laboratories 

 a considerable quantity of apparatus and chemicals, together with stan- 

 dards of electromotive force, resistance, and mass. The results of the 

 meeting are very valuable, and a full report is in process of preparation. 



Another careful research on the silver voltameter has been made 

 during the year by Professor F. Laporte at the Laboratoire Central 

 d'Electricite. Professor Laporte shows that the result obtained in 

 1908 by Professors Janet, de la Gorce, and himself, is subject to an 

 appreciable error, owing to the use of silver nitrate, now known to be 

 impure. With carefully prepared nitrate, and using the Eayleigh form 

 of voltameter, he obtains 1/11829 milligram per coulomb for the 

 electro-chemical equivalent of silver, the current being measured in 

 terms of the Weston cell as 1'01830 volt at 17° C. and the inter- 

 national ohm as realised at the National Physical Laboratory. The unit 

 of current was, therefore, the same as that used by Smith, Mather, 

 and Lowry in 1908, and the value for the electro-chemical equivalent 

 found by Professor Laporte is in very close agreement with the value 

 1"11827 obtained by the British investigators. 



The General Committee at Winnipeg accepted the recommendation 

 of the Council and the Committee of Section A in favour of the republi- 

 cation of all the Eeports of the Electrical Standards Committee. Suit- 

 able arrangements for the work have, therefore, been made, and the 

 material is now with the printer, but in consequence of the absence 

 of Mr. F. E. Smith in America, and the work of preparation required, 

 progress has necessarily been slow. 



With regard to progress in electrical standardising work at the 

 National Physical Laboratory, the Lorenz apparatus is practically com- 

 plete, and some preliminary electrical measurements will, it is hoped, 

 be made in October of the present year. 



The Ayrton-Jones current balance continues to work most satis- 

 factorily, and small and gradual changes in e.m.f. of Weston cells, 



