Los Angeles herald., 1908-09-13

think an account OF what, can now pe uone
IN this direction viii be very interesting to
them, especially as I also intend to give them
explicit directions as to the production OF
the light ON a small scale for themselves.
Now, when we talk Of the Electric light"
we may mean one of two things-either the
sarc" light or the ssincandescent' system Of
lighting. The difference between these needs,
therefore, is to be explained.
The are light Is one of the most intense
lights known, the only light that can COM
pete with it being the light caused by burn
ing piece Of chalk in the mixture Of oxygen
and hydrogen gases known as the oxyhydrogen
blowpipe.
more Familiarity the '1imelight." 1t is much
used for Illuminating large magic lanterns,
and the gases are contained Desperately, or
common coal gas may be used instead of hy-
drogen) IN the large beIowsike gas-bag, which
is placed on the floor.
The electric "arc" light is caused by a very
strong current of electricity passing through
two pencils made of carbon. Suppose we
have very powerful current flowing through
two. wires, one of which is attached to each
OF the carbon pencils, and these are made to
touch each other.
AS long as they are touching nothing will
happen, but when they are separated at about
an inch distance the current has to jump
from one to the other if it is to go on, and If
it is very powerful current it will readily
do so.
But il not only jumps across from one to
the other, but in SO doing it carries with it
q number Of particles Of the carbon pencil
from which it Jumps and in jumping across
and tearing off the particles of carbon it gives
out so much heat that the points Of the pen
ellis and the detached particles are heated to
white heat; and this is the cause of the
brilliant white. light which we see.
This form of light needs such strong cur
rent that It would be quite beyond the power
OF any but experts to produce, and would be
very dangerous for young folks to work with
il they could do so.
light the pencils of carbon have to be kept
at an equal distance apart while they are
burning, and to do this a c1ockwork arrange
ment generally worked by the currently is
Necessary, as the carbons gradually burn away
The particles are carried across from one
pencil TO the other, one becoming sharpened
as it burns, and the other followed out into
a concave form
Owing to these various causes the arc light
Is very expensive TO set up and maintain, and
It 1t were not so, it could only be used in
large halls and in outdoor places on account
OF the brilliant light produced which would
be too firing to the eyes If used to light up
our houses.
But the other species of electric light gives
a much more subdued illumination, and lends
itself much more readily to the lighting up
of an ordinary house, for which it is there
fore always used when the electric light is
wanted.
The light in this case is produced by the
current passing through very thin wire, or
flament as it is called, inside small glass
globe. Two little pieces of platinum wire
globe, and between the ends that are inside
the globe is the thin wire or filament.
This flament is made of bamboo cane
which has been carbonized-i. e., converted
inventor of the lamps, havin~ tried many sub.
stances for. experiment, has hit on bamboo
cane as being the moet suitable
Now, if to the ends Of the platinum wire
that are outside. the globe we attach the
wires through which a strong current is pass
ing, the current win nave to fight its way
through the thin flament in the lamp If 4
means to get round. This it does accordingly
but in SO doing II makes the wire SO hot BY
struggling against the resistance which it op
bright white heat, and gives out very con.
siderable amount OF light
Now it may occur to some intelligent youth
to inquire how long this minute flament Of
carbon will Withstand the action of the cur
rent, when the thick, substantial pieces form.
ing the pencils in the arc lamp were burnt
in a few hours. Well, it sounds rather mys
FERROUS at first sight. but this little ilament
win stand tie action Of the current, which
heats it to wilderness for at least one thousand
hours. often for three thousand or four thou
sand and sometimes five thousand hours. while
the thick carbon pencils last at most for ter
or twelve hours at time. according to their
size. The explanation of this is easily under,
stood when the structure Of the lamps Is ex
nlained. Supposing that we take a lump d
charcoal and heat it to whiteness, or ever
redness. in ordinary air it disappears il q
very short time. Now suppose that, instead
Of heating IL in the air we heat it to the same
degree OF heat in a vessel from which all the
air has been taken out, we find that the char
coal does not d;sappear-for however long a
time we heat it.
The reason Of this is, that in the forne,
case it unites with the oxygen OF the air t.
disappears, becoming invisible. In the latter
case it has no oxygen to combine with, .and
consequently It cannot form the gas, and SC
simply becomes heated without disappearing
OF the ineandescent lamp withstands the eff
fe.A "a Laniirn ,uhile The larra nencila Of the