152 Revolution of a Magnet without Visible Support. 
such a manner that a pencil of light may be seen passing to one 
extremity, and then the leather be so inclined that the distance 
from the other extremity to the band is but half the distance of 
that receiving the electricity, the jet still continues to flow in its 
first direction in preference to taking the shorter path offered by 
the opposite end. There is evidently a tendency in the fluid to 
follow in the direction first commenced. 
For the pu of ascertaining whether metallic particles 
would become luminous in an atmosphere highly charged with 
electricity, very minute particles of metallic dust were projected. 
against the belt, but I was unable to detect any light either during 
their ascent or descent. The passage of a jet of steam through 
the same atmosphere was not attended with light. 
Let two imperfect conductors be placed at equal distances from 
the band, their points directed towards it and separated a few 
inches from each other, then if air be blown violently from a 
glass tube upon one of the jets, it will disappear; the other now 
conveying a larger quantity of the fluid becomes brighter; let 
the tube be directed to this and it is extinguished, the light ap- 
pearing again upon the first, thus changing from one to the other 
as rapidly as the tube can be moved. 
It hence appears probable, that the flickering of the Auroral 
columns may, to a certain extent, be attributable to the motion 
of the air. 
es 
Arr. X XIX.—Revolution of a Magnet on its own Axis without 
the use of Mercurial Conductors, and also without Visible 
Support ; by Cuas. G. Pace, M. D., Prof. Chem., Columbian 
College, Washington, D, C. 
Tue rotation of a magnet upon its own axis is among the most 
interesting of all the phenomena connected with the reciprocal ac- 
tion of magnets and currents, and various ingenious improvements 
have been made upon the original device of Ampére for its illus- 
tration. 'The use of mercurial conductors—a feature common to 
them all—is objectionable for several reasons. ‘T'o dispense with 
the mercurial cells, and substitute for them solid conductors, seem- 
ed to require some other changes in the arrangement, by which 
greater magnetic power should be employed, than can be impart- 
ed to bars of steel of the dimensions usually adopted. The fric- 
tion of a platinum wire attached to the magnet in the usual man- 
ner, and revolving in a circular cell of mercury, though very triv- 
ial in itself, operates considerably to retard the motion of the 
rs sade for the reason that the point of resistance is very far from 
e centre of motion. By the substitution of solid connexions 
+. 
