8 Professor Faraday [Jan. 19, 



it to the prominent corners ; bismuth moved up into it ; and a third like 

 pole on the opposite side made the place of weak force still weaker 

 and larger ; another pole or two made it very weak ; six poles 

 brought it to the condition above described. Even four poles, put 

 with their longer edges together, produced a lengthened chamber 

 with two entrances ; and a little needle being carried in at either 

 entrance passed rapidly through spaces of weaker and weaker force, 

 and found a part in the middle where magnetic action was not 

 sensible. 



Other very interesting results were obtained by making chambers 

 in the polar extremities of electro-magnets. A cylinder magnet, 

 whose core was 1 * 5 inches in diameter, had a concentric cylindrical 

 chamber formed in the end, 0*7 in diameter, and 1"3 inches 

 deep. When iron filings were brought near this excited pole, they 

 clung around the outside, but none entered the cavity, except a very 

 few near the outer edge. When they were purposely placed inside 

 on a card they were quite indifferent to the excited pole, except that 

 those near the mouth of the chamber moved out and were attracted 

 to the outer edges. A piece of soft iron at the end of a copper 

 wire was strongly attracted by the outer parts of the pole, but 

 unaffected within. When the chamber was filled with iron filings 

 and inverted, the magnet being excited, all those from the bottom 

 and interior of the chamber fell out ; many, however, being caught 

 up by the outer parts of the pole. If pieces of iron, successively 

 increasing from the size of a filing to a nail, a spike, and so on to a 

 long bar, were brought into contact with the same point at the 

 bottom of the inverted chamber, though the filing could not be 

 held by attraction, nor the smaller pieces of iron, yet as soon as 

 those were employed which reached to the level of the chamber 

 mouth, or beyond it, attraction manifested itself; and with the 

 larger pieces it rose so high that a bar of some pounds weight could 

 be held against the very spot that was not sufficient to retain an iron 

 filing. 



These and many other results piove experimentally, that the 

 magnetic dualities cannot appear alone ; and that when they are 

 developed they are in equal proportions and essentially connected. 

 For if not essentially connected, how could a magnet exist alone ? 

 Its power, evident when other magnets, or iron, or bismuth is near 

 it, must, upon their removal, then take up some other form, or exist 

 without action: the first has never been shown or even suspected ; 

 the second is an impossibility, being inconsistent with the conserva- 

 tion of force. But if the dualities of a single magnet are thrown 

 upon each other, and so become mutually related, is that in right 

 lines through the magnet, or in curved lines through the space 

 around ? That it is not in right lines through the magnet (it being 

 a straight bar or sphere) is shown by this, that the proper means as 

 a helix round the magnet, shows that the internal disposition of the 

 force (coercitive or other) is not affected when the magnet is exert- 



