338 THE MAGNET. SECT. XXXIV. 



respect to the magnetic equator, and the higher or lower inten- 

 sity of its previous magnetic state. 



A comparison of the number of vibrations accomplished by the 

 same magnetised needle during the same time at different dis- 

 tances from a magnet gives the law of paramagnetic intensity, 

 which follows the inverse ratio of the square of the distance a 

 law that is not affected by the intervention of any substance 

 whatever between the magnet and the needle, provided the sub- 

 stance be not itself susceptible of magnetism. Induction and the 

 reciprocal action of magnets are therefore subject to the laws of 

 mechanics ; but the composition and resolution of the forces are 

 complicated in consequence of four forces being constantly in ac- 

 tivity, two in each magnet. Mr. Were Fox discovered that the 

 law of the paramagnetic force changes from the inverse square of 

 the distance to the simple inverse ratio when the distance between 

 two magnets is as small as from the fourth to the eighlh of an 

 inch, or even as much as half an inch when the magnets are 

 large ; and in the case of repulsion, that the change takes place 

 at a still greater distance, especially when the two magnets differ 

 materially in intensity. 



Without assuming any hypothesis of what magnetism is, or how 

 that force is originated or sustained, Dr. Faraday regards a 

 magnet as a source of power surrounded by curved lines of force 

 which are not only representants of the magnetic power in 

 quality and direction, but also in quantity an hypothesis which 

 accords perfectly with experiment, and with the action both of 

 electricity and magnetism. The nature and form of these lines 

 may be seen by placing a bar magnet upon a table, spreading a 

 sheet of stiff paper over it so as to be perfectly level and free 

 from creases, and then sifting very clean iron filings through 

 a fine sieve equably over it. The filings will instantly assume 

 the form of the curved lines represented by fig. 1, plate 7, in 

 consequence of the action of the magnet. These lines are the 

 true representatives of the magnetic forces, and being related to 

 a polar power, they have opposite qualities in opposite directions. 

 When a magnet is broken across the middle, each part is at once 

 converted into a perfect magnet ; the part that originally had a 

 south pole acquires a north pole at the fractured end ; the part 

 that had originally a north pole gets a south pole ; and as far as 

 mechanical division can be carried, it is found that each fragment 



