Action of Magnets on Copper and good Conductors. 463 



ness, intervene between the poles and the copper bar, the 

 same results occur. 



2322. If one magnetic pole only be employed the effects 

 occur near it as well as before, provided that pole have a face 

 large in proportion to the bar, as the end of the iron core 

 (2246.) : but if the pole be pointed by the use of the conical 

 termination, or if the bar be opposite the edge of the end of 

 the core, then they become greatly enfeebled or disappear 

 altogether; and only the general fact of repulsion remains 

 (2295.). 



2323. The peculiar effects which have just been described 

 are perhaps more strikingly shown if the bar of copper be 

 suspended perpendicularly, and then hung opposite and near 

 to the large face of a single magnetic pole, or the pole being 

 placed vertically, as described (2246. 2263.), anywhere near 

 to its side. The bar, it will be remembered, is two inches in 

 length by 0'33 of an inch in width, and 0*2 of an inch in 

 thickness, and as it now will revolve on an axis parallel to its 

 length, the two smaller dimensions are those which are free to 

 move into new positions. In this case the establishment of the 

 magnetic force causes the bar to turn a little in accordance 

 with the effects before described, and the removal of the mag- 

 netic force causes a revulsion, which sends the bar spinning 

 round on its axis several times. But at any moment the bar 

 can again be caught and held in a position as before. The 

 tendency on making contact at the battery is to place the 

 longest moving dimension, i. e. the width of the bar, parallel to 

 the line joining the centre of action of the magnet and the bar. 



2324. The bar, as before (2311.), is extremely sluggish and 

 as if immersed in a dense fluid, as respects rotation on its own 

 axis ; but this sluggishness does not affect the bar as a whole, 

 for any pendulum vibration it has continues unaffected. It is 

 very curious to see the bar, jointly vibrating from its point of 

 suspension (2249.) and rotating on its axis, when first affected 

 by the magnetic force, for instantly the latter motion ceases, 

 but the former goes on with undiminished power. 



2325. The same effect of sluggishness occurs with a cube 

 or a globe of copper as with the bar, but the phaenomena of 

 the first turn and the revulsion cease (2310. 2315.). 



2326. The bars of bismuth and heavy glass present no ap- 

 pearance of this kind. The peculiar phaenomena produced by 

 copper are as distinct from the actions of these substances as 

 they are from ordinary magnetic actions. 



2327. Endeavouring to explain the cause of these effects, 

 it appears to me that they depend upon the excellent con- 



