Chap. 6.] DireStiw Power of Magnets. 41 



the fame principles, a magnet is cut through the axis, 

 the parts or fegments of the (lone, which before were 

 united, will now repel and avoid .each other *. If two 

 magnets of a fpherical form are freely fufpended, 

 one will conform itfelf to the other, as to the poles of 

 the earth. This influence of one magnet over another 

 is termed the directive power, and this directive power 

 2<5ts at a greater diftance than that of attraction. This 

 may be proved by placing one magnet at the bottom 

 of a fcale, and holding the other at the fame diftance 

 at which it acts in altering its direction : in this cafe 

 no degree of attraction will be produced f. Jf a 

 ^quantity of iron filings are gently dufted on a magnet, 

 they will arrange themfelves around it in a very whim- 

 fical manner : this effect is only to be accounted for 

 from the directive power of the magnet, for the filings 

 by contact with the magnet afiume the magnetic vir- 

 tue, that is, become each of them a fmall magnet, and 

 arrange themfelves according to the polarity of the 

 original magnet J. 



Neither the directive nor the attractive power of the 

 magnet is diminiflied by the interpofition of a foreign 

 body. Steel filings fcattered on a plate of metal, or 

 of wood, or of any body not magnetic, will be affected 

 by the motions of a magnet under the plate 5 and fer- 

 rugineous bodies are attracted with the fame eafe, and 

 at the fame diftance, in the vacuum of an air-pump, 

 as in the open air . 



Natural magnets are frequently found to have more 

 than two poles. That is, the poles of another mag- 

 net of the regular form will frequently be attra&ed by 

 different parts of the furface. This circumftance de- 

 pends on the form and heterogeneous nature of thefe 



* Adams on Mag. p. 444. f Cav. p. 98. { Ib. 



Nicholfon's Phil. ii. p. 296. $ Enfidd's Inftit. p. 340. 



irregular 



