192 PROCEEDINGS OF THE AMERICAN ACADEMY 



nients as these give no data whatever for a physical theory of magnet- 

 ism, and can all be deduced from the ordinary mathematical theory, 

 which is independent of physical hypothesis, combined with what is 

 known with regard to the magnetizing function of iron. This will be 

 shown in the paper I am rewriting. 



It seems to me that M. Jamin's method is very defective ; and I 

 know of no method of experimenting, which is theoretically without 

 objection except that of induced currents, and this I have used in all 

 my experiments on magnetic distribution for the last four or five years, 

 and have developed into a system capable of giving results in absolute 

 measure. Mr. Jacques is to be congratulated on pointing out these 

 errors in M. Jamin's conclusions. 



Tkot, June 7, 1875. 



