ON STANDARDS FOR. USE IN ELECTRICAL MEASUREMENTS. 



129 



tenth-ohm coils were weighted so as to press firmly on to the copper 

 bottoms. No variation was produced by shifting the ten-ohm coil in 

 its cup. 



One or two Leclanche cells wore used in the various experiments : the 

 coils were in water-baths and the temperatures read by a standardised 

 Kew thermometer. 



The standard coils used were^ 



Elliott 264= l-f-000.312(^-15-45). 

 Nalder3715= 1 f -000260 (<- 14-9.^). 

 Elliott 289 = 10 + -002600 {t - 15-40). 



The results of the experiments are given in the following table. 



In the results of the experiments made after January 15 the two 

 values given correspond to the two positions of the coil in the mercury 

 cup. They are included to show the magnitude of the error, which may 

 be due to the resistance of the copper bottoms of the cup. 



Tables fjivin/j Values of Nalder No. 4274 ^ No. 389 in terms of the Ohm 



Standards of the Association. 



Thus, the values of the coils at 15° -2 are respectively for 



;^ 389 . . -100050 ohm, 

 and for 



^ 390 . . -100053 ohm, 



while in each case the resistance introduced by placing the contact pieces 

 of the tenth- ohm coils at some distance from those of the other coila is 

 -000004 ohm 



1894. K- 



