INDUCTION ON A STEEL MAGNET. 



161 



there is attraction, opposed to the magnetic repulsion : 

 and the total repulsion is diminished. The same holds 

 if the blue pole of the first is presented to the blue pole 

 of the second. 



The most accurate information which we possess on 

 the subject is given by Mr W. Ellis, Assistant of the 

 Royal Observatory, Greenwich, in a paper published in 

 The Philosophical Magazine, May 1863, page 325. A 

 magnet 5 J inches long was attached to a clock-pendulum, 

 and a similar magnet was so fixed in the clock-case that 

 one pole of the swinging magnet passed over one pole 

 of the fixed magnet : when there was attraction, the 

 clock was accelerated ; when there was repulsion, the 

 clock was retarded ; and both effects could be measured 

 with extreme accuracy. The following results (ex- 

 tracted from a series) will shew the difference of the 

 effects : 



and these may be thus divided ; 



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