Magnetic Effects of Vibration in Iron Bods. 



529' 



square, consisting of about 200 turns of insulated copper 

 wire and connected through a three-valve amplifier A to 



telephone receivers. The coil was brought near the cable 

 or rod in three typical positions: — 



Position C. The coil in the same plane as the conductor; 

 in this position it would detect any oscillating field 

 having a component whose lines are concentric with 

 the conductor. 

 Position P. Axis of coil parallel to conductor ; in this 

 position it would detect any oscillating field having a 

 component whose lines are parallel to the conductor. 

 Position R. Axis of coil at right angles to and passing- 

 through the conductor ; in this position it would 

 detect any component whose lines are radial to the 

 conductor. 

 During the observations the rod was placed roughly in 

 the magnetic meridian. The orientation of the bar, however, 

 did not appear to have much influence on the character of 

 the observation. 



General Observations. 



The following observations apply equally to all modes of 

 vibration of the bar. 



(a) Coil near cable. 



When the coil was placed near the cable in position 0, 



