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. 
66 66 66 66 ce 26 18 east. 
Armature partially detached, fs 7 east. 
Armature entirely detached, “6, I2edemer 
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. 
From 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 iron; and a cur- 
rent 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 induced 
electricity : all the helices were stationary while the iron rod revoly- 
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-electric current by a rotatory 
motion of the iron combined with its sudden magnetization. 
The same apparatus however furnished the means of measuring 
separately the relative power of motion and induction in producing 
electrical currents. The iron rod was first magnetized by currents 
