KFFECT OF bTllE^S üX MACiNETIZATlUX. 



'à 



iii;ii;iK'liziug coil which was one that liad l)eeii used in our previ- 

 ous cx])ei'iments, was placed in its vertical position. The length 

 and ilie constant of the coil were respectively 40 cm. and 392.6. 

 A secondary coil was wound on a glass tube (external diameter 

 1.5 cm.), consisting of 1246 turns of well insulated copper wire 

 (diameter=0.56 mm.) in 6 layers, the length of the coil being 

 14 cm. This secondary coil was fixed coaxially in the magnetiz- 

 ing coil, so that the former might lie in a uniform field excited 

 by the latter. 



To compensate for the induc- 

 tion due to the magnetizing field 

 alone, a similar secondary coil con- 

 nected in series with the above 

 secondary coil was inserted within 

 another coil equal to and connected 

 in series with the magnetizing coil, 

 so that by sliding the secondary 

 within the primary, the induction 

 could be compensated to any desired 

 degree. These two pairs of coils 

 were placed at a sufficient distance 

 from eacli other to prevent their 

 mutual action. The ballistic gal- 

 vanometer for measuring the 

 induced current due to the magne- 

 tization of the specimen was drum- 

 Ô shaped, with 0.8 -^«^ resistance ; a 

 mirror with a small magnet w^as 

 suspended in the center of the coil by a spider thread. Its 

 period of oscillation was about seconds. The galvauijuieter was 



