12 General Laio of' Magneto-Electric Induction. 



on the conductor will, as Mr. Faraday has shown, take place 

 in the opposite direction. 



2. If two conductors, having electricity induced on them 

 in the same direction by means of an elementary battery, be 

 placed parallel to one another, they will be mutually attracted. 

 Hence, if we remove one of the batteries and connect the ends of 

 the wires as in the first experiment, and then imitate attraction, 

 by making the wires rapidly approach each other in a parallel 

 position, the same electric influence will be induced on the 

 closed circuit as it had when connected with the battery. If 

 the conductors, when connected with the batteries, have their 

 electricities induced in opposite directions, they will mutually 

 repel each other. Hence, if we remove one of the batteries, 

 connect the wires as before, and imitate repulsion, by re- 

 moving the wires rapidly from each other, the electric influ- 

 ence or current will be induced in the same direction as it was 

 when the wires were connected with the battery. 



S. If a voltaic conductor be made to revolve round the 

 pole of a magnet, as in Mr. Faraday's first experiment on ro- 

 tation, and if the battery be removed and the ends of the con- 

 ductors brought into metallic contact, the same electric state 

 will be induced on the closed circuit, by turning the wire ra- 

 pidly round the pole of the magnet by mechanical force. 



4. If we produce all the rotations described in works on 

 electro-magnetism, and if we remove the battery, and bring 

 the ends of the conductors into metallic contact, and then 

 continue the rotation by mechanical means, the same electric 

 state will be induced on the conductor which it had when 

 connected with the battery. v 



In a paper of mine read before the Royal Society on the 

 21st of March 1833*, I first described the method of making 

 a piece of soft iron or electro-magnet, either straight or in 

 the form of a horse-shoe, revolve rapidly round its centre, 

 either by the action of the earth or of a horse-shoe magnet, 

 by changing its poles twice in every revolution. Hence Irom 

 the general law it follows, that if- the soft iron be made to re- 

 volve by mechanical force, the same electric state will be in- 

 duced on the conductor as it had when the ends of the wires 

 were connected with the battery. 



These facts were known, and the experiments publicly exhi- 

 bited, months before the large revolving electro-magnet was 

 exhibited in the Adelaide Rooms. The general law at which 

 we have arrived may be thus expressed : " If a wire conducting 

 voltaic electricity, produce by its action on magnets or con- 

 ductors certain motions, as attractions, repulsions, or continued 

 • Slc Lund, and Edinb. Phil. Mag., vol. iii. p. 145.— Edit. 



