The silver state news. [volume] (Winnemucca, Nev.) 1907-1909, 1909-01-23

was then in it's infancy. Today, the
humber of central stations in this
country alone number 5577. But it
is not my purpose in this article 70
speak of central stations nor of the
equally interesting topic, electric dis
tribution, any more than to define
few descriptive terms.
BY "Central Station" is meant the
engines and dynamos which supply
current to the lighting circuit together
with the building in which they are
housed. The "mains' are the wires
wires by which the current is led from
the central station to the transformers
located at various points near where
the current is used for lighting. The
wire leading from the transformer to
the house and the return wire from
the house to the transformer are
called "lcads.'' Smaller wires from
the leads to individual lamps are
called distributing wires. -
The use of poorly insulated wire for
inside wiring or careless planning and
bad workmanship in putting in the
wire may be the occasion of a fire, but
if tbe wiring is properly done, fires
caused by electric lighting wires are
almost impossible. What danger there
is comes from the possibility of the
leads getting connected directly (for
instance, by having their insulation
abraded, thus allowing them to come
in contact with each other or with
metal fixtures or wet walls) the cur.
rent will then pass through this short
circuit because it offers less resist
anee than the lamps. With the les
sened resistance the current may be
come so great as to heat the wires
themselves to temperature that will
cause them to set fire to the woodwork
of the building. AS precaution
against -eyerheating in the leads, a
short piece of lead wire called "a
fuse" is made to form part of the
circuit. In case, then, of accidental
"short circuit the suddenly in
creased current Immediately melts or
elbows out'' this fuse, thus opening
the circuit and stopping the current
before the wires become heated enough
to do any damage.
Electrical contact between the
lamps and distributing wires is made
through the bases of the lamps and
the sockets on the distributing wire.
nectted to two contacts in the base
which, in turn, connect up with two
contacts in the socket. Unless ar
ranged to be controlled by wall
switches, the sockets contain switches
to turn on or off the current.
The incandescent lamp is a thing of
gradual growth, so much so, that no
one can be said to be its "inventor. -
But we owe our present lamp princi-
pally to the work of Edison and Swan
between the years 1877 aand 1850.
Platinum wire served as filament
for the earliest lamps but it was liable
to sudden rupture if overheated. The
great improvement came with the use
of carbon filaments of high resistance
enclosed in vacuum. OF late years
other filaments have been found that
are superior to carbon.
TO better appreciate these changes
1t may be well to briefly discuss the
general subpect of illumination, trae-
ing its relation TO heat radiation. !
suppose no one who has ever given
the matter any thought at all imagines
that it is leetricity he sees when he
looks at the incandescent flament OF
lamp. Electricity is invisible, con
sequently we cannot perceive electric
ity itself, but only the effects which ~
produces.
The electric energy used in over
coming the resistance of the lamp fiji
through it is converted into heat. The
heat produced in the filament is pro
portional to the current squared times
the resistance of the filament. Bui
this is equal to the watts expended IN
the filament or to the difference OF
potential at its terminals (volts) mul.
tiplied by the current flowing in il
(amperes.)
The ordinary lamp of 16 candle
power consumes 55 watts. On the 10
volt circuitfi the current is one.fourtl
ampere (220xh equals 55). With ]
voltage Of 110, to secure current OF
ne-half ampere, the resistance of thF
flament has to be 220 ohms.
A carbon flament having this re
sistance, and sufficient cross-section tc
give mechanical strength, should be
a n fUyl i -