192 PROCEEDINGS OF THE AMERICAN ACADEMY 



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

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

 which is independent of phj^sical 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. 



Teot, June 7, 1875. 



