36 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XX.) 
2321. When plates of copper or bismuth, an inch in thickness, 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 termi- 
nation, 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 remem- 
bered, is two inches in length by 0‘33 of an inch in width, and 02 of an inch in thick- 
ness, and as it now will revolve on an axis parallel to its length, the two smaller di- 
mensions 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 magnetic 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 phenomena of the first turn and the revulsion cease (2310. 2315.). 
2326. The bars of bismuth and heavy glass present no appearance of this kind. 
The peculiar phenomena 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 conducting power of copper for electric currents, the 
gradual acquisition and loss of magnetic power by the iron core of the electro-mag- 
net, and the production of those induced currents of magneto-electricity which I de- 
scribed in the First Series of these Experimental Researches (55. 109.). 
2328. The obstruction to motion on its own axis, when the bar is subjected to the 
magnetic forces, belongs equally to the form of a sphere or a cube. It belongs to 
these bodies, however, only when their axes of rotation are perpendicular or oblique 
