4 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXIV.) 
form of cylinders, three-fourths of an inch in diameter and 24 inches long, were 
dropped through it, or else raised through it with an accelerated velocity; but in 
neither case was any effect produced. Rods of copper, bismuth, glass, shell-lac and 
sulphur were employed. Occasionally these rods were made to rotate rapidly 
before and during their fall ; and many other conditions were devised and carried 
into effect, but always with negative results, when sources of error were avoided or 
accounted for. 
2711. On further consideration of the original assumption, namely, a relation be- 
tween the forces, and of the effects that might be looked for consequent upon a con- 
dition of».tension in and around the particles of the body, which, as we know, are at 
the same moment the residence of both gravitating and electric forces, and are sub- 
ject to the gravitation of the eartli, it seemed probable that the stopping of the up 
and down motion (2703. 2704.) in the line of gravity would produce contrary effects 
to the coming on of the motion, and that, whether the stopping was sudden or 
gradual; also that a motion downward quicker than that which gravity could com- 
municate, would give more effect than the gravity result by itself, and that a corre- 
sponding increase in the velocity upwards would be proportionally effectual. In such 
case a machine which could give a rapid alternating up and down motion, might be 
very useful in producing many minute units of inductive action in a small space and 
moderate time; for then, by proper commutators, the accelerated and retarded parts 
of each half-vibration could be separated and recombined into one consistent current, 
and this current could be sent through the galvanometer during the time its needle 
was swinging in one direction, and afterwards reversed for the time of a swing in the 
other direction ; and so on alternately until the effect had become sensible, if any 
were produced by the assumed cause. 
2712. The machine which I had 
made for this purpose is that de- 
scribed in the last Series of these 
Researches (2643.), the electro- 
magnet, the experimental core and 
the rod which carried them being 
removed ; — a, b, c frame-board ; 
d,d,dwooden lever, of which e is the 
axis ; /'the crank-wheel, and g the 
great wheel with its handle h ; i the 
barconnecting the crank-wheel and 
lever ; q the galvanometer ; r the 
commutator ; w, connecting wires ; 
s, s springs of brass or copper ; t a 
copper rod connecting the two arms of the lever to give strength ; u the hollow helix 
fixed, or moveable at pleasure. The plan is to a scale of one-fifteenth. Being on a 
