On Electricity. 163 
By comparing the indents made in the tin-foil, it ap- 
pears that the two forces acting in contrary directions are 
nearly equal; but as no satisfactory conclusion could be 
drawn from these phevomena, I contrived an electrometer, 
by which these forces are compared to a3 great a degree of 
precision as the nature of the subject seems to require. 
In fig. 3. Plate I]. ABCD is a card placed in a vertical 
position upon a stand; EF, two thin pieces of mahogany 
which slide upon the card, by means of slits cut in them 
with a fine saw. 
px and nx two pieces of wire sliding through E and F; 
px is placed on one side of the card and 22 on the other, 
their ends being opposite to ong another at the point 2. 
G, a piece of wood fixed upon the top of the card, from 
which two pendulums of equal dimensions and weight are 
suspended at J, on opposite sides of the card, having the 
centres of their bobs covering the points of the wires at x. 
One of these pendulums az is suspended on this side of 
the card, upon the pin 0; but the other, being on the other 
side of the card, is not seen in the figure. The pendulum 
rods are made of very thin slips of mahogany, and the bobs 
of card paper. . 
~ When the instrument is adjusted, the ends of the wires 
are placed exactly between the two centres of the bobs at x, 
where a small circular opening is made, between the ends 
of the two pieces of wood, to give free passage to the elec- 
tric fluid. 
When a charge from a coated surface is passed through 
the wires, the card is perforated, and the pendulums are 
thrown off in contrary directions ; and, as far.as [ am able 
to judge by inspection, to equal distances from the perpen- 
dicular *. 
Hence it appears an established law of nature, that all 
electrical pheenomena are produced, by two distinct powers 
acting in contrary directions, and with equal energy. 
And these invisible agents seem to exist in every particle 
of matter, eliher in a state of rest or a state of action, ac- 
cording to their different modifications. But till that law 
which governs these modifications shall be perfectly un- 
derstood, we must be content with observing effects, with- 
out knowing their causes. 
To be continued in my next communication, 
Iam, dear sir, your obedient servant, 
Lynn, August 4, 1813. Ez. WALKER. 
* Asthe wires nxp and the point of suspension of the pendulums are 
adjustable, the same card may serve for many experiments. 
" La KXVIII. Mr. 
