FE. L. Carney—LHffect of Vibrations upon Electro-magnets. 208 
to the left 40°, and upon breaking the circuit it is deflected 
40° to the right. The signs in our table denote this change 
of direction. When the poles are reversed and the circuit 
ing upon each second and succeeding passages of the current 
to constant deflections. The following are the results when a 
bar of steel was substituted for the soft iron. 
TasBLE II. 
Distances of C from the middle of the bar in 
imeters. 
Constant deflections on making and breaking) +|—|+|—)+)—|+ 
circuit. /20/ 20/30/30 40/40/50 50/60/60 70/70 
Deflections on the first passage of the current 
after changing the poles. 7 
Return to constant deflections on second and)/—}+ } + ol ie aad ak 
i sages of the current. 120120 30'30.40'40'50'50 60'60'70'70 
In the case of steel, when the coil C stands at a distance of 
five centimeters from zero, the galvanometer needle swings 
+20° to —20°. 
No. XIL—On the Effect of Longitudinal Vibrations upon Electro- 
magnets; by HE. L. CARNEY. ; 
Ir a bar of iron or steel which is rendered magnetic by a 
magnetizing spiral receives a sharp blow or shot 
current is generated in a coil of fine wire, which is slipped upon 
the bar and is connected with a galvanometer. This current 
is opposite in direction to that of the magnetizing current. 
(Wiedemann, Galvanismus und Elektromagnensmus, 1863, pp. 
375, 897. Also Dr. Emil Villari, Veber den transversalen Magne- 
tismus des Eisens und des Stahles, Pogg. Ann., exxxvii, 1869, pp. 
569-591.) This investigation was.undertaken to ascertain the 
