must be coated on the
inside; and while it is charging, at every spark taken from the
conductor into the inside, a flash of light is seen to dart at the
same time from every part of the external surface of the phial, so as
to quite fill the receiver. Upon making the discharge, the light is
seen to run in a much closer body, the whole coming out at once.

_The Illuminated Cylinder._

Provide a glass cylinder, three feet long, and three inches diameter;
near the bottom of it fix a brass plate, and have another brass plate,
so contrived that you may let it down the cylinder, and bring it as
near the first plate as you desire. Let this cylinder be exhausted and
insulated, and when the upper part is electrified, the electric matter
will pass from one plate to the other, when they are at the greatest
distance from each other that the cylinder will admit. The brass plate
at the bottom of the cylinder will also be as strongly electrified as
if it were connected by a wire to the prime conductor.

The electric matter, as it passes through this vacuum, presents a most
brilliant spectacle, exhibiting sparkling flashes of fire the whole
length of the tube, and of a bright silver hue, representing the most
lively exhalations of the aurora borealis.

_The Electric Aurora Borealis._

Make a Torricellian vacuum[G] in a glass tube, about three feet long,
and hermetically sealed.[H] Let one end of this tube be held in the
hand, and the other applied to the conductor; and immediately the
whole tube will be illuminated from one end; and when taken from the
conductor will continue luminous, without interruption, for a
considerable time, very often about a quarter of an hour. If, after
this, it be drawn through the hand either way, the light will be
uncommonly brilliant, and, without the least interruption, from one
end to the other, even to its whole length. After this operation,
which discharges it in a great measure, it will still flash at
intervals, though it be held only at the extremity, and quite still;
but if it be grasped by the other hand at the same time, in a
different place, strong flashes of light will dart from one end to the
other. This will continue for twenty-four hours, and often longer,
without any fresh excitation. Small and long glass tubes, exhausted of
air, and bent in many irregular crooks and angles, will, when properly
electrified, exhibit a very beautiful representation of vivid flashes
of lightning.