the Laws of Magnetic Forces. 297 



further magnetic developement is induced by neutralizing a por- 

 tion of the opposing force. 



The force thus neutralized will, from what has been stated 

 (29), depend on the inductive force of the magnet, and its dis- 

 tance from the iron ; so that the increased attractive power of 

 the magnet at its opposite pole, is still a measure of the induc- 

 tive effect. 



31. The fact itself (30) is very well illustrated by placing a 

 short magnetised piece of steel b c, Fig. 5, to act on the suspend- 

 ed cylinder x at a constant distance ; and, after observing the at- 

 tractive force ; by subsequently opposing a mass of soft iron m very 

 near the inferior pole, in which case the index will be found to 

 advance. The effect is more decided when the iron m is brought 

 into contact. The law of this action is, as in the former case, 

 directly proportionate to the power of the magnet, and inverse- 

 ly proportional to the distance. Thus, a small magnetised piece 

 of hardened steel b c, Fig. 5, three inches long, eight-tenths of an 

 inch wide, and three-tenths of an inch thick, being caused to act on 

 the suspended cylinder x at four-tenths of an inch distance, the 

 indicated attraction amounted to 12. On approximating a si- 

 milar mass of iron m, within two-tenths of an inch of its inferior 

 pole, the index moved forward 1 ; on diminishing the distance 

 to the one-tenth of an inch, the index moved forward another 

 degree. 



32. The effect thus produced by approximating a mass of iron 

 toward the opposite pole of a magnet, has not any relation to 

 the dimensions of the iron, all other things remaining the same ; 

 thus furnishing an additional confirmation of the curious fact 

 before mentioned (27), that the proximate poles of magnets by 

 induction are of equal intensity. 



