ON STANDARDS FOR USB IN ELECTRICAL MEASUREMENTS. 



147 



APPENDIX. 



On the Values of some Standard Resistance Coils. By the Secretary and 



T. C. Fitzpatrick. 



In the last report the values of the Standard Legal Ohm Coils of the 

 Association are given. For the one-ohm coils the temperatures range 

 from 11° to 18°, while the coils of higher resistance were examined only 

 at tenaperatures near 17°. It was necessary in all cases to extend the 

 range of temperatures in order to determine the temperature coefficient. 

 The observations were made by the methods already described in the 

 Reports, and the values found are given in the following tables in which 

 the previous results are included : — 



Resistance Coil, .IS*. 100. 



Mean value 

 Temperature coefficient 



•999510 at 1418°. 

 •000271 per 1° C. 



Mean value 

 Temperature coefficient 



Mean value of whole series . 

 Temperature coefficient 



■998401 at 1010°. 

 •000274 per 1° C. 



•998770 at 1228°. 

 000272. 



These results are represented graphically in Plate IV. by the 

 curve ^j 100, which is drawn through the means derived from the two 

 series, and represents within the limits of accuracy of the experiments all 

 the observations of the two series, the mean error from the curve, omitting 

 one observation, being about '00002. 



In the diagram the circles indicate the observations of 1884-5 ; the 

 dots those of 1885-6. 



