new phenomenon of electro-magnetism. 1 55 
the action of the magnet ; and that the appearances which I 
have described were owing to a composition of forces. 
I endeavoured to ascertain the existence of these motions 
in the mercury, by covering its surface with weak acids ; and 
diffusing over it finely divided matter, such as the seeds of 
lycopodium, white oxide of mercury, &c. but without any 
distinct result. It then occurred to me, that from the position 
of the wires, currents, if they existed, must occur chiefly in 
the lower, and not the upper surface of the mercury : and I 
consequently inverted the form of the experiment. I had two 
copper wires, of about one-sixth of an inch in diameter, the 
extremities of which were flat and carefully polished, passed 
through two holes three inches apart in the bottom of a glass 
basin, and perpendicular to it ; they were cemented into the 
basin, and made non-conductors by sealing-wax, except at 
their polished ends ; the basin was then filled with mercury, 
which stood about a tenth or twelfth of an inch above the 
wires. The wires were now placed in a powerful voltaic 
circuit. The moment the contacts were made, the phenomenon , 
which is the principal object of this paper, occurred : the mer- 
cury was immediately seen in violent agitation ; its surface 
became elevated into a small cone above each of the wires ; 
waves flowed off in all directions from these cones ; and the 
only point of rest was apparently where they met in the centre 
of the mercury between the two wires. On holding the pole 
of a powerful bar magnet at a considerable distance ( some 
inches) above one of the cones, its apex was diminished 
and its base extended : by lowering the pole further, these 
effects were still further increased, and the undulations were 
feebler. At a smaller distance the surface of the mercury 
