ROTATION OF BODIES NEAR MAGNETS. 33 



with the ends of the wire connected with a gold- 

 leaf electroscope, D. When the coil E is slipped 

 down over the pole 

 of a horse-shoe mag- 

 net, s, the electric 

 ether pervading the 

 spiral coil A, being 

 put in motion through 

 the circuit of the wire 

 ABE, traverses the 

 strip of gold-leaf be- 

 tween the two verti- 

 cal poles of another Fig. 7 . 

 magnet, N s, whereby the flexible gold-leaf is moved 

 toward the spectator during the continued descent 

 of the spiral coil A. An opposite deflection of the 

 gold-leaf occurs on lifting and taking away the 

 spiral coil. By alternately approaching and with- 

 drawing the spiral coil of conducting wire, corre- 

 sponding electric surges move back and forth in 

 tidal waves, and the gold-leaf swings back and 

 forth correspondingly. 



These movements, being made slowly, are less 

 effective than when made rapidly, by rotating 

 the spiral coils inclosing a piece of iron bended 

 to the same horse-shoe form, as represented in 

 Fig. 8. The iron is rendered magnetic when the 

 two ends pass by the opposite poles of a per- 

 manent horse-shoe steel magnet, N. A wheel 

 and band, w, are used to increase the velocity 



3 



