322 MAGflETO-ELECTrmCITY. SECT. XXXlli. 



SECTION XXXIII. 



Magneto-Electricity Volta-Electric Induction Magneto-Electric Induc- 

 tion Identity in the Action of Electricity and Magnetism Description 

 of a Magneto-Electric Apparatus and its Effects Identity of Magnetism 

 and Electricity. 



FROM the law of action and reaction being equal and 

 contrary, it might be expected that, as electricity pow- 

 erfully affects magnets, so, conversely, magnetism ought 

 to produce electrical phenomena. By proving this veiy 

 important fact from the following series of interesting 

 and ingenious experiments, Dr. Faraday has added 

 another branch to the science, which he has named 

 magneto-electricity. A great quantity of copper wire 

 was coiled in the form of a helix round one half of a 

 ring of soft iron, and connected with a galvanic battery ; 

 while a similar helix connected with a galvanometer was 

 wound round the other half of the ring, but not touching 

 the first helix. As soon as contact was made with the 

 battery, the needle of the galvanometer was deflected. 

 But the action was transitory ; for when the contact 

 was continued, the needle returned to its usual position, 

 and was not affected by the continual flow of the electri- 

 city through the wire connected with the battery. As 

 soon however as the contact was broken, the needle of 

 the galvanometer was again deflected, but in the con- 

 trary direction. Similar effects were produced by an 

 apparatus consisting of two helices of copper wire coiled 

 round a block of wood, instead of iron, from which Dr. 

 Faraday infers that the electric current passing from the 

 battery through one wire, induces a similar current 

 through the other wire, but only at the instant of con- 

 tact, and that a momentary current is induced in a con- 

 trary direction when .the passage of the electricity is 

 suddenly interrupted. These brief currents or waves 

 of electricity were found to be capable of magnetizing 

 needles, of passing through a small extent of fluid, and 

 when charcoal points were interposed in the current of 

 the induced helix, a minute spark was perceived as often 



