is a forcible argument against the mechanical theory of positive
and negative electricity; because then the flame should be blown
towards the point in one case, and from it in the other.

So the electric fly, as it turns horizontally, recedes from the
direction of the points of the tangents, whether it be electrised with
vitreous or resinous electricity; whereas if it was supposed to
receive electricity, when electrised by resin, and to part with it
when electrised by glass, it ought to revolve different ways; which
also forcibly opposes the theory of positive and negative electricity.

As an electrised point with either kind of electricity causes a stream
of air to pass from it in the direction of the point, it seems to
affect the air much in the same manner as the fluid matter of heat
affects it; that is, it will not readily pass through it, but will
adhere to the particles of air, and is thus carried away with them.

From this it will also appear, that points do not attract electricity,
properly speaking, but suffer it to depart from them; as it is there
less attracted to the body which it surrounds, than by any other part
of the surface.

And as a point presented to an electrised conductor facilitates the
discharge of it, and blows the flame of a candle towards the
conductor, whether vitreous or resinous electricity be accumulated
upon it; it follows, that in both cases some electric matter passes
from the point to the conductor, and that hence there are two electric
ethers; and that they combine or explode when they meet together, and
give out light and heat, and occupy less space in this their combined
state, like the union of nitrous gas with oxygen gas.

IV. _Accumulation of Electric Ethers by Contact._

The electric ethers may be separately accumulated by contact of
conductors with nonconductors, by vicinity of the two ethers, by heat,
and by decomposition.

Glass is believed to consist in part of consolidated resinous ether,
and thence to attract an electric atmosphere round it, which consists
of a greater proportion of vitreous ether compared to the quantity of
the resinous, as mentioned in Proposition No. 4. This atmosphere may
stand off a line from the surface of the glass, though its attractive
or repulsive power may extend to a much greater distance; and a more
equally mixed electric atmosphere may stand off about the same
distance from the surface of a cushion.

Now when a cushion is forcibly