458 Dr. Faraday's Researches in Electricity. 



face c l\ inches in diameter. A small indicating sphere (2266.) 

 of bismuth hung over the centre of this face and close to it, 

 does not move by the magnetism. If the ball be carried out- 

 wards, half way, for instance, between the centre and the edge, 

 the magnetism makes it move inwards, or towards the axis 

 (prolonged) of the iron cylinder. If carried still further out- 

 wards, it still moves inwards under the influence of the mag- 

 netism, and such continues to be the case until it is placed 

 just over the edge of the terminal face of the core, where it 

 has no motion at all (here, by another arrangement of the ex- 

 periment, it is known to tend in what is at present an upward 

 direction from the core). If carried a little further outwards, 

 the magnetism then makes the bismuth ball tend to go out- 

 wards or be repelled, and such continues to be the direction 

 of the force in any further position, or down the side of the 

 end of the core. 



229.9. In fact, the circular edge formed by the intersection 

 of the end of the core with its sides, is virtually the apex of 

 the magnetic pole, to a body placed like the bismuth ball close 

 to it, and it is because the lines of magnetic force issuing from 

 it diverge as it were, and weaken rapidly in all directions from 

 it, that the ball also tends to pass in all directions either in- 

 wards or upwards, or outwards from it, and thus produces 

 the motions described. These same effects do not in fact all 

 occur when the ball, being taken to a greater distance from 

 the iron, is placed in magnetic curves, having generally a 

 simpler direction. In order to remove the effect of the edge, 

 an iron cone was placed on the top of the core, converting 

 the flat end into a cone, and then the indicating ball was 

 urged to move upwards, only when over the apex of the cone, 

 and upward and outwards, as it was more or less on one side 

 of it, being always repelled from the pole in that direction, 

 which transferred it most rapidly from strong to weaker points 

 of magnetic force. 



2300. To return to the vertical flat pole : when a horizontal 

 bar of bismuth was suspended concentrically and close to the 

 pole, it could take up a position in any direction relative to 

 the axis of the pole, having at the same time a tendency to 

 move upwards or be repelled from it. If its point of suspen- 

 sion was a little excentric, the bar gradually turned, until it 

 was parallel to a line joining its point of suspension with the pro- 

 longed axis of the pole, and the centre of gravity moved inwards. 

 When its point of suspension was just outside the edge of the 

 flat circular terminating face, and the bar formed a certain 

 angle with a radial line joining the axis of the core and the 

 point of suspension, then the movements of the bar were un- 



