24 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XX.) 
*j[ ii. Action of magnets on heavy glass. 
2253. The bar of silicated borate of lead, or heavy glass already described as the 
substance in which magnetic forces were first made effectually to bear on a ray of 
light (2152.), and which is two inches long, and about 0*5 of an inch wide and thick, 
was suspended centrally between the magnetic 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 sus- 
pension, 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 bar 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 equa- 
torial position. 
2255. Neither did any change in the magnetism of the poles, by change in the di- 
rection 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 comple- 
tion 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 har arrives at the equa- 
torial position ; or if the bar be originally in the equatorial position, then the mag- 
netism 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 them, 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 excited. On allowing the mag- 
netism to pass away, the bar returns to the place due to it by its gravity. 
2260. Precisely the same effect takes place at the other pole of the magnet. Either 
of them is able to repel the bar, whatever its position may be, and at the same time 
the bar is made to assume a position, at right angles, to the line of magnetic force 
