INDUCED MAGNETISM IN SOFT IRON. 131 



force to take a position other than north and south (as 

 for instance, if suspended by two threads as in the ap- 

 paratus for measure of small changes of horizontal force, 

 Article 85), the presentation to it of a bar of soft iron 

 end-on to the center will slightly disturb it : but to a 

 degree very much less than that of which we shall speak 

 in the next article. 



57. Experiments on the induction of magnetism in 

 Soft Iron by the action of a Steel Magnet. 



In Figures 46 and 48, suppose that A is a steel magnet 

 Fig. 46. m a vertical position (it matters little whether 

 the red end is upwards or downwards : in the 

 diagram it is supposed that the red end is up- 

 wards). In Figure 46 suppose that G is a small 

 bar of soft iron (as a small nail) lying on a table 

 so far below A that the action of A will not 

 . c . sensibly disturb G. Suppose that B in Figure 47 

 Fio . 47 is a bar of soft iron (as a larger nail) which, alone, 

 would not disturb G. Now let the bar B be 

 placed under A as in Figure 48 (in which case 

 the magnet A if sufficiently powerful will sup- 

 port By the reason of which we shall hereafter 

 1 explain), and B will immediately lift the small 



bar G. If the bar B be held in the left hand, and A 

 in the right, then, upon detaching A from B, G will 

 immediately drop off. On the other hand, if the con- 

 nexion of A, B, and G, be maintained, G will support a 

 piece of iron wire D, as in Figure 48. And this series 

 may sometimes be continued through several steps. 



92 



