a 
Researches in Magnetic Electricity. 369 
necessary to make a few brief preliminary observations, and to 
advert to the discoveries which led to its invention. When a 
piece of soft iron enclosed in a helix of wire, is rendered a mag- 
net, by the approach of a magnetized bar, a current of electricity 
flows through the helix (during the development of magnetism) 
in a direction contrary to that of a galvanic current, which would 
render the piece of soft iron a magnet of the same character. 
Withdraw the inducing magnet, and during its withdrawal, or 
the neutralizing process in the piece of soft iron, the direction 
of the electric current in the helix will be the same as that of 
a galvanic current which would render the soft iron a magnet 
of similar polar arrangement. Similar momentary currents are 
excited when the exciting cause is a galvanic current. Comple- 
ting the galvanic circuit with the helix, determines a current 
flowing against the battery current. Breaking the circuit, deter- 
mines a current flowing in the same direction with the battery 
current, which produces the bright spark. Any disturbance of 
Magnetic forces is accompanied with a disturbance of electric 
equilibrium. It is well known, that an electro-magnet possessing 
an immense lifting power when its poles are joined by an arma- 
ture, exerts a comparatively feeble action at a distance. The 
reason i is this: the two magnetic forces or poles are tending con- 
stantly to neutralize or disguise each other, the softness of the 
iron favors this mutual action, and the whole amount of magnet- 
ism developed cannot be perceived, until the magnetic forces are 
insulated or determined towards the poles by the application of 
an armature. The application then of the armature must occa- 
sion a considerable disturbance or movement of magnetic forces, 
and give rise to an electrical current in the wires. ‘The direc- 
tion of this current can easily be predicted, from what has been 
before said. The application of the armature is equivalent to the 
_ further development or separation of magnetic forces: hence the 
‘New current will flow against the battery current. When the ar- 
~ Mature is pulled off, the new current is in the same direction as 
that of the battery. And if the magnet-wires be so arranged that 
the galvanic circuit may be broken at the instant of pulling off 
armature, it will be found that the magneto-electric spark and 
shock will be far greater, than can be obtained by simply break- 
ing the circuit, without the aid of this operation. ‘Thus we have 
~& new method a augmenting to a great degree the magneto-elec- 
47 
Vou. XXXIV.—No. 2. 
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