Section III., 1914 [89] Trans. R.S.C. 



On the Use of the Kelvin-Varley Slide Potentiometer. 

 By A. Norman Shaw, M.Sc, 



Macdonald College, McGill University. 



Presented by Prof. H. T. Barnes, F.R.S., F.R.S.C. 



Read May 27, 1914. 



The Kelvin-Varley Slide has been described in many electrical 

 works, 1 and is well known as a valuable and accurate instrument. It 

 has been found that an exceptional accuracy can be obtained if refined 

 calibrations are occasionally performed. After making several trials 

 of various methods, Prof. Callendar, in connection with his research 

 on "Continuous Electrical Calorimetry", 2 briefly outlined the one 

 which he considered to bë the most convenient and accurate. It was 

 thought that a more detailed account and slight extension of the 



theory and practice of this calibration would be of service, and these 

 notes are recorded therefore for the purpose of assisting anyone to 

 perform it in a short and simple manner. 



1 Price — "Measurement of Electrical Resistance", p. 106. 



Fleming — "Handbook for the Electrical Laboratory and Testing Room", 



Vol. I., p. 273. 

 Munro and Jamieson — "Pocket Book of Electrical Rules and Tables", p. 158. 

 Kempe — "Handbook of Electrical Testing", p. 219. 

 Aspinall Parr — "Practical Electrical Testing", p. 321. Etc., etc. 



2 Phil. Trans. A., Vol. 199, 1902, p. 65. 



