Los Angeles herald., 1907-04-21
EXPERIMENTS,

touch the table while the experiment is per
formed. Let him place his hand on the tray
while the paper is heated rubbed and placed
thereon.
He will then become charged with electri
city, and If he approaches his hand to any
one elscs, a spark will pass between them.
(This should not be done with susceptible
parts of the body, the eyes. for example, as
it would be rather painfully Let some one
De provided with spoon in which little
methylated spirit is heated: if the charged
person holds his knuekle to this spirit, it
VIII instantly be ignited. Small pieces of
paper-comlc paper fgures-will dance up and
down briskly if he holds his hand outspread
over them while lying on the table
The same thing will happen if the pieces
OF paper are placed between the tray and the
table when the former is charged by the hot
paper, or if the brown paper in the tray be
held above them when excited.
=. Now. take needle and place it on the tray,
Its point projecting over the edge. If the
room is now darkened, on placing the ex-
cited paper on the tray, the point of the
needle will be seen to glow brilliantly for
some seconds
This is caused by the electricity escaping
into the air from the point of the needle,
and is known as the brush discharge" The
tray will consequently speedily lose its electric.
spark from the tray as long as the needle is
on it, as the electricity vastly prefers to
escape by the point. The escape of the elect ric-
ity may be rendered still more evident by
means of the following piece Of apparatus:
Take two pieces of thin wire about two
inches long, and bend each at right angles
about an eighth of an inch from each end,
both the bent portions being in the same di-
rection. These two pieces of wire are now
to be joined together at the middle at right
angles by means of piece of finer wire
twisted around them.
This finer 1Uira oop with l;+tla ooro bo
caused to form small cap, i'll which the
point of a needle is inserted, the needle act
ing as pivot, so that the bent wires turn
freely on the top of it Gig. ~.
The needle is supported by thrusting it
into large cork to act as a stand A fine
wire is then twisted several times round the
bottom of the needle, and the whole appara-
tus is placed on the tray, the end of the wire
attached to the needle being carefully ar
ranged SO as to touch the tray, metallic con-
nection with the tray being essential to sue
cess.
If the needle can be soldered to a metal
stand, or the cork covered with tinfo, the
wire is not needed.
On rubbing the paper and placing it on
the tray the electricity passes up the wire
into the needle, thence into the wire cross,
and escapes by the bent portions of the
wires, each of which should be fled to a
point.
In escaping it electrifes the surrounding
air, and this, according to the law that ''hke
electricities repel each other" has reacting
force on the wire arms. Accordingly the
windmill begins to turn, and may attain
tolerable rate of speed if the tray is strongly
charged.
Another very anusing experiment is that
known as the electrical head of hair"
The head of wooden doll is taken, and
either provided with a real head of hair, which
must be combed out straight, or a quantity
OF cotton is fastened to it to resemble hair.
and placed on the tray when the excited paper
is laid upon it, the hairs become charged, and
consequently repel each other, causing the
whole head of hair to stand erect, each hair
separate from the rest, thus presenting most
remarkable appearance