202 INDUCTIVE AFFINITY. 



filaments of iron, each of which has individually the properties 

 of a separate magnet. The displacement or separation of the 

 two attractive powers takes place only within these small par- 

 ticles, which are called the magnetic elements, and must be 

 supposed so minute, that they may be the ultimate particles or 

 atoms themselves of the iron. A magnetic bar may therefore 

 -p be represented (as in 



the figure) as composed 



riH~ ^ mmu ^ e portions, the 

 | right hand extremities of 

 * each of which possess one 



species of magnetism, and the left hand extremities the other. 

 The shaded ends being supposed to possess boreal, and the light 

 ends austral magnetism, then the ends of the bar itself, of which 

 these sides of the elementary magnets form the faces, possess re- 

 spectively boreal and austral magnetism, and are the boreal and 

 austral poles of the magnet. Such, then, is the polarized condi- 

 tion of a bar of iron possessing magnetism, of which the attractive 

 and repulsive powers residing at the extremities are the results. 

 Of the existence of such a structure, the breaking -of a magnet 

 into two or more parts affords a proof, for it forms as many 

 complete magnets as there are parts, new poles appearing at all 

 the fractured extremities. 



-p 5 Magnetical induction. When to the boreal pole 



B of a magnet (Fig. 5.), which may be of the horse- 

 shoe form, a piece of soft iron a b, wholly destitute 

 of magnetic powers, is presented, a similar dis- 

 placement of the magnetic forces of its elements 

 occurs as in the magnet itself; or a b becomes 

 a magnet by induction, and may attract and in- 

 duce magnetism in a second bar a 1 b 1 ; both of 

 which continue magnetic so long as the first re- 

 mains in the same position, and under the in- 

 fluence of A B. These induced magnets must 

 have the same polarized molecular structure as 

 the original magnet, but their magnetism is only temporary, 

 and is immediately lost when they are removed from the per- 

 manent magnet. The displacement of the magnetisms in these 

 induced magnets commences at the extremity a of a b, in contact 

 with B, which extremity has the opposite magnetism of B, (the 

 different kinds of magnetism being mutually attractive,) and is the 

 austral pole of a b; and b is its boreal pole. Of a 1 b', again, the 



