400 Dr. Faraday's Researches in Electricity. [Series xx. 



and which is two inches long, and about 0*5 of an inch wide 

 and thick, was suspended centrally between themagnetic poles 

 (2247.)» and left until the effect of torsion was over. The 

 magnet was then thrown into action by making contact at the 

 voltaic battery : immediately the bar moved, turning round its 

 point of suspension, into a position across the magnetic curve 

 or line of force, and after a few vibrations took up its place of 

 rest there. On being displaced by hand from this position, it 

 returned to it, and this occurred many times in succession. 



2254". Either end of the bar indifferently went to either side 

 of the axial line. The determining circumstance was simply 

 inclination of the bar one way or the other to the axial line, 

 at the beginning of the experiment. If a particular or marked 

 end of the b#r were on one side of the magnetic, or axial line, 

 when the magnet was rendered active, that end went further 

 outwards, until the bar had taken up the equatorial posi- 

 tion. 



2255. Neither did any change in the magnetism of the 

 poles, by change in the direction of the electric current, cause 

 any difference in this respect. The bar went by the shortest 

 course to the equatorial position. 



2256. The power which urged the bar into this position 

 was so thoroughly under command, that if the bar were 

 swinging it could easily be hastened in its course into this 

 position, or arrested as it was passing from it by seasonable 

 contacts at the voltaic battery. 



2257. There are two positions of equilibrium for the bar; 

 one stable, the other unstable. When in the direction of the 

 axis or magnetic line of force, the completion of the electric 

 communication causes no change of place ; but if it be the least 

 oblique to this position, then the obliquity increases until the 

 bar arrives at the equatorial position ; or if the bar be origi- 

 nally in the equatorial position, then the magnetism causes no 

 further changes, but retains it there (2298. 2299. 2384.). 



2258. Here then we have a magnetic bar which points 

 east and west, in relation to north and south poles, i. e. points 

 perpendicularly to the lines of magnetic force. 



2259. If the bar be adjusted so that its point of suspension, 

 being in the axial line, is not equidistant from the poles, but 

 near to one of then), then the magnetism again makes the bar 

 take up a position perpendicular to the magnetic lines of force ; 

 either end of the bar being on the one side of the axial line, 

 or the other, at pleasure. But at the same time there is 

 another effect, for at the moment of completing the electric 

 contact, the centre of gravity of the bar recedes from the pole 

 and remains repelled from it as long as the magnet is retained 



