of Magneto-Electricity. 



351 



slowly, they were bright and snapping*; increasing the rapi- 

 dity of revolution, they decreased in brightness : until at a 

 velocity of about 370 per minute they ceased altogether. 

 They were plainly visible again when the velocity reached 

 600 per minute. 



The results of the preceding series of experiments are col- 

 lected in the following table along with theoretical results 

 calculated in precisely the same manner as those of Table I. 

 The correction for heat evolved by the iron of the revolving 

 electro-magnet is estimated at 0°*18, the product of 0, 28 by 



/ — \ ; because in the above experiments the large electro- 

 magnet was excited by §■ of the battery used when 0, 28 was 

 obtained. No correction is needed for the series in which the 

 steel magnets were used, because they remained in their places 

 during the interpolating experiments. 



Table J I. 



In all these experiments, as well as in those collected in 

 Table I, the time occupied by the platinum wires in crossing 

 the divisions of the commutator was found to be exactly £ of 

 that occupied by an entire revolution. Hence the multipli- 

 cation by \ in order to obtain true theoretical results on the 

 supposition that the current flows uniformly during £ of a 

 revolution. It will be observed that these theoretical results 



* The most splendid sparks are obtained when the voltaic is assisted by 

 the magneto-electricity, by turning an electro-magnetic engine in a direc- 

 tion contrary to the attractive forces. 



