218 ROSA, DORSEY AND MILLER: INTERNATIONAL AMPERE 



100,000 a quantity equal to twice the average deviation from the 

 mean. 



The value given by the combination iV4 L3 L4, which was 

 omitted from the mean, was 1.01825 2 . 



The weight to be attached to the final mean is considerably 

 increased on account of the fact that three pairs of fixed coils, 

 two large and one small, and two moving coils, of different radii, 

 have been used. The possibility of the occurrence of appreciable 

 constant errors in the work is thereby very much diminished. 



Other observers in England, France and Holland have recently 

 published results obtained by means of various types of instru- 

 ments. When reduced to the same basis as used above, the values 

 obtained are as follows: 



The absolute value of the electrochemical equivalent of silver 

 as obtained from the current balance of the Bureau of Standards 

 and 159 silver deposits made by Rosa, Vinal and McDaniel in 

 this laboratory with two types of voltameters is 1.11804 mg. per 

 coulomb. The value adopted by the London Conference in 

 1908 was 1.11800. In other words, the international ampere as 

 defined by means of the silver voltameter, as used at the Bureau 

 of Standards, differs from the absolute ampere as realized there 

 by means of the current balance by only four parts in 100,000. 



When the absolute value of the international ohm is as accu- 

 rately known as the absolute value of the international ampere is 

 now known, the watt can be realized with high precision from the 

 international watt, by applying as a correction the small dif- 

 ference between them. Even now the most accurate way of 

 measuring energy or power absolutely is by means of electrical 

 instruments. 



