of Magneto-Bledricity. 



m 



Although any considerable development of electrical cur- 

 rents in the iron of the revolving electro-magnet was prevented 

 bj f its disposition in a number of thin plates insulated from each 

 other, I apprehended that they might, under a powerful in- 

 ductive influence, exist separately in each plate to such an 

 extent as to produce an appreciable quantity of heat. To as- 

 certain the fact, the terminals of the wire of the revolving 

 electro-magnet were insulated from each other, while the latter 

 was subjected to the inductive influence of the large electro- 

 magnet excited by ten cells in a series of five double pairs. 

 The experiments were interpolated with others in which con- 

 tact with the battery was broken. As we shall hereafter give 

 in detail experiments of the same class, it will not be necessary 

 to do more at present than to state that the mean result of the 

 present series, consisting of eight trials, gave o, 28 as the 

 quantity of heat evolved by the iron alone. 



We are now able to collect the results of the preceding 

 experiments so as to discover the laws by which the develop- 

 ment of the heat is regulated. The fourth column of the 

 following table, containing the heat due to the currents cir- 

 culating in the iron alone, is constructed on the basis of a law 

 which we shall subsequently prove, viz. the heat evolved by a 

 bar of iron revolving between the poles of a magnet is propor- 

 tional to the square of the inductive force. Column 5 gives 

 the heat evolved by the coils of the electro-magnet alone. No 

 elimination is required for the results of series Nos. 5 and 6, 

 because in them the iron of the revolving electro-magnet was 

 subject to the influence of the steel magnets in the interpo- 

 lating, as well as in the other experiments. 



Table I. 



Phil. Mag. S. 3, Vol. 23. No. 152. Oct. 1843. 



