RELATION OF GRAVITY TO ELECTRICITY. 
5 
moveable frame, it could be placed in any position. The cylinder of metal or other 
substance to be submitted to its action, was 5^ inches long and three-fourths of an 
inch in diameter, and was firmly held between the ends d, d of the lever arms. The 
extent of the alternating motion was 3 inches. A hollow cylindrical helix u, 2^ 
inches in length, and of such internal diameter that the cylinders could complete 
their rapid journeys to and fro within it without any danger of striking against its 
sides, was constructed, containing 516 feet of covered copper wire ; this cylinder could 
be either fixed immoveably or attached firmly to the cylinder under experiment so as 
to move with it. The wires from this helix passed to the commutators and from 
them to the galvanometer. Part of the momentum of this machine was taken up by 
springs s, s (2648.), and converted into the contrary motion ; but so much remained 
undisposed of thus, that great care was required in fixing and strutting to render the 
action of the whole very steady, or else derangement quickly occurred at the cylinder 
and helix, and electro-currents were frequently produced. 
2713. The employment of cylinders of iron, copper and other substances in this 
machine, was competent to produce electro-currents in various ways. Thus, iron 
might produce magneto-electric currents consequent upon its polar condition under 
the influence of the earth ; these it would be easy to detect and separate by the use 
of adjusted magnets, which should neutralize or reverse the lines of magnetic force 
passing through the iron. Currents like those induced in copper cylinders and good 
conductors (2663. 2684.), might be produced by the earth’s action; but as the lines 
of gravitating force and of terrestrial magnetic force are inclined to each other, these 
might be separated by position ; and it appeared that there was no source of error 
that might not by care be eliminated. 1 will not occupy time by describing how this 
long lesson of care was learned, but pass at once to the chief results. 
2714. The copper cylinder (2712.) was placed in the machine, and the helix fixed 
immoveably around it, the whole being in such a position that the cylinder should be 
vertical, and move up and down parallel to the line of gravitating force within the 
helix. However rapidly the machine was worked, or whatever the position of the 
commutator, there was no result at the galvanometer. Cylinders of bismuth, glass, 
sulphur, gutta percha, &c., were also employed, but with the same negative conclu- 
sion. 
2715. Then the helix was taken from its fixed support and fastened on to the 
copper cylinder so as to move with it, and now very regular and comparatively large 
effects were produced. After a while, however, these were traced to causes other than 
gravity, and of the following kind. The helix was fixed at one end of a lever, at a 
point 22 inches trom its axis, and being 2 inches in diameter its wires on one side 
were only 21 inches, and on the other side 23 inches from this axis. Hence, in vibra- 
ting these parts travelled with velocities and through spaces which are as 21 : 23. 
When therefore their paths were across the lines of magnetic force of the earth, 
electro-currents tended to form in these different parts proportionate in amount or 
