Evening star. [volume] (Washington, D.C.) 1854-1972, 1905-04-26
HOUSEHOLD ELECTRICITY.
The Dry Cell on the Battery, the Cur
rent and Call Bell.
From Harper's Weekly.

From Harpers Weekly.
Even should your household otherwise
lack electrical appliances, you are sure to
have an electric call-bell. The generator of
the electric current, which is stored away
in some out-of-the-way corner, IS probably
small so-called dry CELL" which you
could readily carry around in your pocket;
or it may consist of receptacle holding a
pint or two of liquid in which some metal
plates are immersed. Such an apparatus
seems scarcely more than toy when we
contrast it with the gigantic dynamOs of the
power house; yet, within the limits of its
capacities, one is as surely a generator of
electricity as the other. If we are to ac-
cept the latest theory, the electrical current
which flows from this tiny cell is precisely
the same in kind that which flows from
the 5,OOO-horSe- power dynamo The differ
enCe is only of quantity
To understand the operation of this ia
miliar household appliance must bear in
mind two or three familiar experimental
facts in reference TO the action of the voltaic
cell. Briefly, such cell consists of two
plates of metal-for example, one of copper
and the other of Zinc-with connecting
medium, which is usually a liquid but
which may be a piece of moistened cloth or
biotting paper. So long the two plates of
metal are not otherwise connected there is
no electricity in evidence, but when the two
are joined by any metal conductor. as, for
example, piece of wire thus, in common
parlance completing the circuit cur
rent OF electricity flows about this circuit
passing from the first metal plate to the
second, through the liquid and back from
the second plate to the first through piece
of wire. The wire may be of any length.
In the case of your call bell, for example,
the wire circuit extends to your door, and is
there broken, shutting off the current. When
You press the button you connect the broken
ends of the wire, thus closing the circuit as
the saying is, and the re-established cur
rent acting through a little electromagnetic
rings the bell. In another case the wire
may be hundreds of miles in length, to
serve the purposes of the telegrapher, who
transmits his messages by opening and
closing the circuit precisely as you operate
your door bell. For long distance teleg-
raphy, of course, large cells are required
and numbers of them are linked together to
give a cumulative effect, making a strong
current; but there is no new principle in
volved.
The simplest study of this interesting
mechanism makes IL clear that the cell Is
the apparatus primarily involved in gener
ating the electric current; yet it is equally
obvious that the connecting wire plays an
important part, since, as we have seen,
when the wire is broken there is no current
in evidence. Now, according to the electron
theory, as previously outlined, the electric
current consists of an actual flow along a
wire of carriers of electricity which are I'M
able to make their way except where
course is provided for them by what is
called a conductor. Dry air, for. example,
is, under ordinary circumstances, quite i'm
perviOus to them. This means, then, that
the eectrons flow freely along the wire
when it is continuous, but that they are
powerleSs to proceed when the wire Is cut.
When you push the button of your call bell.
therefore, you are virtually closing the
switch which enables the electrons to pro-
coed on their interrupted journey.