248 FRAGMENTS OF SCIENCE. 
a current through the helices, aud observing that the 
magnets swung perfectly free, it was first arranged that the 
bismuth cylinders within the helices had their central or 
neutral points opposite to the poles of the magnets. All 
being at rest the number on the scale marked by the cross 
wire of the telescope was 572. The cylinders were then 
moved, one up, the other down, so that two of their ends 
were brought to bear simultaneously upon the magnetic 
poles: the magnet moved promptly, and after some oscil- 
lations* came to rest at the number 612; thus moving 
from a smaller to a larger number. The other two ends of 
the bars were next brought to bear upon the magnet: a 
prompt deflection was the consequence, and the final 
position of equilibrium was 526: the movement being 
from a larger to a smaller number. We thus observe 
a manifest polar action of the bismuth cylinders upon 
the magnet; one pair of ends deflecting it in one direc- 
tion, and the other pair deflecting it in the opposite 
direction. 
Substituting for the cylinders of bismuth thin cylinders 
of iron, of magnetic slate, of sulphate of iron, carbonate of 
iron, protochloride of iron, red ferrocyanide of potassium, 
and other magnetic bodies, it was found that when the 
position of the magnetic cylinders was the same as that of 
the cylinders of bismuth, the deflection produced by the 
former was always opposed in direction to that produced by 
the latter; and hence the disposition of the force in the 
diamagnetic body must have been precisely antithetical to 
its disposition in the magnetic ones. 
But it will be urged, and indeed has been urged against 
this inference, that the deflection produced by the bismuth 
cylinders may be due to induced currents excited in the 
metal by its motion within the helices. In reply to this 
objection, it may be stated, in the first place, that the deflec- 
tion is permanent, and cannot therefore be due to induced 
currents, which are only of momentary duration. It has 
also been urged that such experiments ought to be made 
with other metals, and with better conductors than bismuth; 
for if due to currents of induction, the better the conductor 
the more exalted will be the effect. This requirement was 
complied with. 
* To lessen these a copper damper was made use of. 
