Dec. 1845.] Action of Magnets on Heavy Glass. 401 



excited. On allowing the magnetism 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, what- 

 ever 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. 



2261. If the bar be equidistant from the two poles, and in 

 the axial line, then no repulsive effect is or can be observed. 



2 62. But preserving the point of suspension in the equa- 

 torial line, i. e. equidistant from the two poles, and removing 

 it a little on one side or the other of the axial line (2252.), then 

 another effect is brought forth. The bar points as before 

 across the magnetic line of force, but at the same time it re- 

 cedes from the axial line, increasing its distance from it, and 

 this new position is retained as long as the magnetism conti- 

 nues, and is quitted with its cessation. 



2263. Instead of two magnetic poles, a single pole may be 

 used, and that either in a vertical or a horizontal position. 

 The effects are in perfect accordance with those described 

 above ; for the bar, when near the pole, is repelled from it in 

 the direction of the line of magnetic force, and at the same 

 time it moves into a position perpendicular to the direction of 

 the magnetic lines passing through it. When the magnet is 

 vertical (2246.) and the bar by its side, this action makes the 

 bar a tangent to the curve of its surface. 



2264. To produce these effects, of pointing across the mag- 

 netic curves, the form of the heavy glass must be long ; a cube 

 or a fragment approaching roundness in form, will not point, 

 but a long piece will. Two Or three rounded pieces or cubes, 

 placed side by side in a paper tray, so as to form an oblong 

 accumulation, will also point. 



2265. Portions, however, of any form, are repelled; so if 

 two pieces be hung up at once in the axial line, one near each 

 pole, they are repelled by their respective poles, and approach, 

 seeming to attract each other. Or if two pieces be hung up 

 in the equatorial line, one on each side of the axis, then they 

 both recede from the axis, seeming to repel each other. 



2266. From the little that has been said, it is evident that 

 the bar presents in its motion a complicated result of the force 

 exerted by the magnetic power over the heavy glass, and that 

 when cubes or spheres are employed, a much simpler indica- 

 tion of the effect may be obtained. Accordingly, when a cube 

 was thus used with the two poles, the effect was repulsion or 

 recession from either pole, and also recession from the mag- 

 netic axis on either side. 



