Daily tobacco leaf-chronicle. (Clarksville, Tenn.) 1890-1895, 1892-03-09
WHAT A DYNAMO IS.
Description OF the Iain Principle of an
Electrical Machine.

VI tuo 4 Ol III
Electrical Machine.
The collection of electricity or its gener-
NEion, as it is often called, is no more or
less mysterious than the generation of
heat For those who make no pretensions
to understand the governing principles I'M
DERIVING the generation of electricity by q
dynamo, we present the following brief ex-
PLANTATION, which we hope may be easily
grasped:
Perhaps every reader has played with q
common horseshoe magnet. No one can
have one on his hand, even for few mo-
ments, without noticing that the small
piece at the two ends called the armature
when brought close to these ends, not be-
ing allowed to touch them, is affected by
some invisible influence which tends to
draw it toward these ends. This mysteri-
GUS influence is called magnetism. On
laying horseshoe magnet on piece of
paper placed in horizontal plane and
loosely sprinkling iron filings around these
ends it can be seen that there is an appar-
ent current of this influence projecting
into space from the ends and running
across the space at the open ends of the
magnet. These imaginary projections or
currents of this mysterious influence are
called Zines of magnetic force"
Here we have the magnetic force, and
the next thing is to get the electricity. BY
moving an armature across these lines of
magnetic force at the ends of a magnet
we find it requires an expenditure of
energy In the case of dynamo we obtain
this energy from steam, water power or
some other source. The generation Of
electricity is us easily understood as the
method of getting power by steam en-
CINE. 1t is known that if we take q con-
ductor of electricity, like common cop
per wire, and by any means cause it to
move through lines of magnetic force in
q certain direction, that electricity will be
developed in this conductor. No one pre-
tends to explain why. This is the whole
mystery of the dynamo, with all its as
tonishing possibilities in the service of
man.
We know how to do it, but are as much
in mystery about the reason nature acts
in this way as we are to explain why an
apple goes down instead of up when rolled
from your open hand.
A dynamo consists principally of two
parts, one of which is large mass of soft
cast or wrought iron called the magnet,
and the other part is called the armature.
Soft iron does not remain permanently as
magnet except to very slight degree.
However, some magnetism always remains
stored up in the iron. There is germ of
magnetism great enough to be easily and
quickly increased when properly handled
by well known methods. The revolving
shaft, as seen in the ordinary dynamo, is
called the nature. The armature is
usually constructed by having hundreds
of insulated copper wires in it and is made
to revolve at a high velocity by some me-
chanical force, such as steam. Suppose
this speed is 1000 revolutions per minute,
which is not unusual, and that we have
500 wires ON this armature, then we will
have, as the armature revolves, what
would be equivalent to single wire cut
ting across al the lines of magnetic force
500, 900 times ach minute.
The magnet generally surrounds the
armature, and these magnetic lines of
force are shooting through the armature
in continuous stream at an inconceivable
velocity. Ali the wire conductors on the
revolving armature as they move through
these lines OF magnetic force are constant
ly picking up their little share of electric
ity and unloading it by means of ingen-
ious mechanical devices connecting with
the conducting wire that leads from the
dynamo, and receiving the returning cleo
tricity on another wire leading back into
the dynamo.
One of natures wonderfully mysterious
laws causes soft iron to become magnetic
when surrounded by current of cleo
tricity. In the ordinary dynamo this law
is of the greatest utility. AS the electrical
current is being collected by the revolving
armature it is led around the magnel and
thus the magnetic germ squicllly changed
into a mighty force, again feeding the
armature which transforms it from mag
netic to electrical force.-Mechanica and
Electrical Progress.