388 Connexion between Magnetism and Electricity. 



N S a wire of iron attached transversely to it, the latter be- 

 comes permanently magnetic. — Sir H. Davy. 



3. If we suppose a second conjunctive wire parallel to, 

 and similarly situated with, the first, as in this figure, those 



PC <N 



P r — i N 



wires will attract each other; but if one conjunctive wire be 

 traversed by the electric fluid in one direction, and another 

 in an opposite direction, as in the following wood-cut, those 



N r a p 



wires will repel each other. In this circumstance, the dis- 

 similarity of the electro-magnetic and of simple electric 

 phenomena is observed : for bodies similarly electrified re- 

 pel each other, and, dissimilarly electrified, attract each 

 other; but here the horizontal wires, similarly electro-mag- 

 netized, attract ; and, dissimilarly electro-magnetized, re- 

 pel each other. — M. Ampere. 



4. The shock of a Leyden jar, or battery, passed through 

 a wire, confers upon it, at the moment of its passage, prop- 

 erties precisely similar to those of the Voltaic apparatus. 



To render a steel bar magnetic, it is not necessary that 

 it should touch the conjunctive wire, to which it is attached 

 at right angles, for the electro-magnetic influence is convey- 

 ed to some distance, and is not excluded by the interposi- 

 tion of a plate of glass, of metal, or of water. — Sir H. Davy, 



5. The phenomena, exhibited by the electro-magnetic 

 or conjunctive wire, may be explained upon the supposition 

 of an electro-magnetic current passing round the axis of 

 the conjunctive wire, its direction depending upon that of 

 the electric current, or upon the poles of the battery with 

 xvhich it is connected. — Dr. Wollaston. 



