406 Electro-Magnetic Experiments. 
flection, it was again deflected in the same direction by partially de- 
taching the armature from the poles of the magnet to which it.con- 
tinued to adhere from the action of the residual magnetism, and in 
this way, a series of deflections, all in the same direction, was pro- 
duced by merely slipping off the armature, by degrees, until the con- 
tact was entirely broken. The following extract from the register of 
the experiments exhibits the relative deflections observed in one ex- 
periment of this kind. 
At the instant of immersion of the battery, deflec. 40° west. 
sé “cs 6 oe 174 oe 18 
east. 
Armature partially detached, sg 7 east. 
Armature entirely detached, ss 42 east 
The effect was reversed in another experiment, in which the nee- 
dle was turned to the west in a series of deflections by dipping the 
battery but a small distance into the acid at first and afterwards im- 
mersing it by degrees. 
rom the foregoing facts, it appears that a current of electricity is 
produced, for an instant, in a helix of copper wire surrounding a piece 
of soft iron whenever magnetism is induced in the irons and a cur- 
rént in an opposite direction when the magnetic action ceases; also 
that an instantaneous current in one or the other direction accompa- 
nies every change in the magnetic intensity of the iron. 
Since reading the account before given of Mr. Faraday’s method 
of producing electrical currents I have attempted to combine the ef- 
fects of motion and induction; for this purpose a rod of soft iron ten 
inches long and one inch and a quarter in diameter, was attached to 
a common turning lathe, and surrounded with four helices of copper 
wire in such a manner that it could be suddenly and powerfully mag- 
netized, while in rapid motion, by transmitting galvanic currents 
through three of the helices; the fourth being connected with the 
distant galvanometer was intended to transmit the current of indueed 
electricity : all the helices were stationary while the iron rod revolv- 
ed on its axis within them. From a number of trials in succession, 
first with the rod in one direction then in the opposite, and next in a 
state of rest, it was concluded that no perceptible effect was produ- 
ced on the intensity of the magneto-electrie current by a rotatory 
motion of the iron combined with its sudden magnetization. 
~The same apparatus however furnished the means of measuring 
eparately the relative power of motion and induction in producing 
‘eurrents. The iron rod was first magnetized by currents 
