without being able to guess the cause.

Care should be taken that the shock be not too strong; and regard
should be had to the constitution and disposition of the party, as a
shock that would hardly affect one person, might be productive of
very serious consequences to another.

Much entertainment may be derived from concealing the chain that
communicates with that which proceeds from the outside of the battery,
under a carpet, and placing the wire that communicates with the chain
from the inside, in such a manner that a person may put his hand on it
without suspicion, at the same time that his feet are upon the other
wire.

The whole company may be made to partake of the shock, by joining
hands, and forming a circle. The experiment may also be varied if they
tread upon each other's toes, or lay their hands upon each other's
heads. It might happen, by the latter method, that the whole company
would be struck to the ground; but it will be productive of no danger,
and very little inconvenience; on the contrary, it has happened that
they have neither heard nor felt the shock.

* * * * *

To exhibit the five following amusements in electricity, the room in
which they are performed must be darkened.

_The Miraculous Luminaries._

You must previously prepare the following phosphorus: Calcine common
oyster-shells, by burning them in the fire for half an hour; then
reduce them to powder; of the clearest of which take three parts, and
of flowers of sulphur one part; put the mixture into a crucible, about
an inch and a half deep. Let it burn in a strong fire for rather
better than an hour; and when it is cool, turn it out and break it in
pieces; and, taking those pieces into a dark place, scrape off the
parts that shine brightest, which, if good, will be a white powder.

Then construct a circular board, of three or four feet diameter, on
the centre of which draw in gum-water, or any adhesive liquid, a
half-moon, of three or four inches diameter, and a number of stars
round it, at different distances, and of various magnitudes. Strew the
phosphorus over the figures, to the thickness of about a quarter of an
inch, laying one coat over the other. Place this board behind a
curtain; and when you draw the curtain up or back, discharge one
electrifying jar or phial over each figure, at the distance of about
an inch, and they will become illuminated, exhibiting a very striking
resemblance of the