INDUCTIVE AFFINITY. 



203 



upper extremity a', in contact with b', is the austral, and the 

 lower extremity Z>', the boreal pole, or b b' have the same kind 

 of magnetic power as the pole B of the original magnet, from 

 which they are dependent. A third bar of soft iron placed at 

 b' is likewise polarized, and the series of induced magnets irfay 

 be still farther extended, but the attractive powers developed 

 in the different members of the series, become less and less 

 with their distance from the pole B of the original magnet. 



FIG. 6. FIG. 7- 



A similar set of bars may be con- 

 nected with A (Fig. 6.), which become 

 temporary magnets also according to the 

 same law, the lower extremities of this 

 set being austral. On now uniting the 

 lower extremities of both sets by another 

 bar of soft iron a" b", (Fig. 7-)> e i tner 

 set renders a" b 11 a magnet, having its 

 austral pole at a" and its boreal pole at 

 b 1 ' ; and acting together, they commu- 

 nicate a degree of magnetism to the 

 uniting bar, greater than either set pos- 

 sessed before they were united. By this 

 connexion also the inductive actions of each set of bars is 

 brought to bear upon the other, and the attractive forces at 

 all their poles are thereby greatly increased. In the most fa- 

 vourable conditions as to the size and connexion of the tem- 

 porary, magnets, with relation to the primary magnet, the 

 former, however numerous, should each acquire powers equal 

 to those of the original magnet. This general enhancement of 

 power in the induced magnets, has been acquired by com- 

 pleting the circle of them between A and B. 



It is also important to observe, with a view to the future 

 application of the remark, that a single bar of soft iron, or 

 lifter, as b a, (Fjg. 8.), connecting the poles of a magnet 

 A B, not only acquires at a and b equal, though opposite 

 FIG. 8. powers to the contiguous poles of the magnet, but 

 also reacts by induction on these poles themselves, 

 and increases their magnetism. The original mag- 

 netic forces of A and B are therefore increased, 

 by the opportunity to act inductively, which the con- 

 necting bar affords them. The threads of steel 

 filings which are taken up by a magnet, (see figure 

 9) illustrate the inductive action of magnetism, 



B 



