Chemistry and Physics. 419 
iron rods whilst under the influence of electric currents. This 
effect is by no i i 
ceed, in some cases, a twist of a quarter of a circle, the end of a 
suitable index moving through a space of eighty centimeters. It 
Is always attended by emission of sound. 
wire surrounding the bar or wire, and the 
oe through the iron itself. The cause of them is the com- 
torsion, i. e., in the directio 
unless the latter has been previously magnetized by the eras 
zine m brass or German silver, or with a 
thick rod of zine, or a cord of gutta-percha.— Nature, Jan. 19th. 
pap 
imitated. But on comparing the velocities requi those 
obtained istering the motion of the wings of real birds, 
