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, hj the approach of a magnetized bar, a current of electricity 

 flows through the helix (dming 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 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 ofi", 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" 

 the 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 

 a new method of augmenting to a great degree the magneto-elec- 

 VoL. XXXIY.— No. 2. 47 



