East and West^ traversed hy an Electric Current. 323 



therefore, a horizontal wh*e perpendicular to the magnetic 

 meridian, if connected first in one way with a Yoltaic battery, 

 and then in the opposite way, should have its weioht altered ; 

 for in the one case it would tend to pass in a circle downwards 

 and in the other upwards. This alteration should take place 

 differently in different parts of the world. The effect is actu- 

 ally produced by the pole of a magnet ; but I have not suc- 

 ceeded in obtaining it, employing only the polarity of the 

 earth." ■ 



In a subsequent paper, of January 1822 *, he examines the 

 point experimentally, saying, after a description f of the mode 

 in which he demonstrated the lateral motion of a wire parallel 

 to itself under the influence of the earth's magnetism : — " Re- 

 verting now to the expectation I entertained of altering the 

 apparent weight of a wire, it was founded on the idea that the 

 wire, moving towards the north round the pole, must rise, 

 and, moving towards the south, must descend ; inasmuch as a 

 plane perpendicular to the dipping needle ascends and descends 

 in these directions. In order to ascertain the existence of 

 this effect, I bent a wire twice at right angles, as in the first 

 experiment described in this note, and fastened on to each 

 extremity a short piece of thin wire amalgamated, and made 

 the connexion into the basins of mercury by these thin wires. 

 The wire was then suspended, not, as before, from the ceiling, 

 but from a small and delicate lever, v/hich would indicate any 

 apparent alteration in the weight of the wire. The connexions 



* Quarterly Journal of Science, xii. 416. 



t " A piece of copper wire, about '045 inch thick, and 14 inches long, 

 had an inch at each extremity bent at right angles, in the same direction, 

 and the ends amalgamated ; the wire was then suspended horizontally, 

 by a long silk thread from the ceiling. A basin of clean, pure mercury 

 was placed under each extremity of the wire and raised until the ends 

 just dipped into the metal. The mercury in both basins was covered 

 by a stratum of diluted pure nitric acid, which, dissolving any film, 

 allowed free motion. Then, connecting the mercury in one basin with 

 one pole of Hare's calorimotor, the moment the other pole was con- 

 nected with the other basin, the suspended wire moved laterally across 

 the basins till it touched the sides : on breaking the connexion, the 

 wire resumed its first position; on restoring it, the motion was again 

 produced. On changing the position of the wire, the eifect still took 

 place ', and the direction of the motion was always the same relative 

 to the wire, or rather to the current passing through it, being at right 

 angles to it. Thus, when the wire was east and west, the east end to 

 the zinc, the west end to the copper plate, the motion was towards the 

 north ', when the connexions were reversed, the motion was towards 

 the south. When the wire hung north and south, the north end to 

 the zinc plate, the south end to the copper plate, the motion was to- 

 wards the west ; when the connexions were reversed, towards the east ; 

 and the intermediate positions had their motions in intermediate 

 directions." 



Y2 



