Evening star. [volume] (Washington, D.C.) 1854-1972, 1892-01-02
WHAT A DYNAMO is.
Popular Description of the Main Principle Of
An Electrical Machine.

Electrical Machine.
J. A. Grer in Mechanical and Electrical Progress.
The collection of electricity, or its genera
ton 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 underlying the gen.
GRAFTON of electricity by a dynamo We present
the following brief explanation, which We hope
may be easily grasped:
Perhaps every reader has played with a COM
mon horseshoe magnet No one can have one
OIL his hand, even for few moments, without
noticing that the small piece at the two ends
called the armature, when brought close to
these ends, not being allowed to touch them, is
affected by some invisible influence which tends
to draw 1t toward these ends. This mysterious
influence is called magnetism. On laying a
horseshoe magnet on u piece of paper placed
in horizontal plane and loosely sprlnkling
iron filings around these ends it can be seen
that there Is an apparent current of this infiu-
ence 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
LINES 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 a dynamo we obtain
| this energy from steam, water power OF some
other source. The generation of electricity is
as easily understood as the method OF getting
power by a steam engine. 1t is known that if
we take a conductor OF electricity, like o COM
mon copper wire, and by any means cause it to
move through lines Of magnetic force in a
certain direction that electricity will be de-
veloped in this conductor. No one pretends
to explain why. This Is the whole mystery of
de Ill ,Ha al.
bilities 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 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 a magnet except to a
very slight degree. However, some magnetism
alwaysremains 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 re-
volyiag shaft, as seen in the ordinary dynamo,
Is Called the armature. The armature is
| usually constructed by having hundreds of in
sulatec copper wires In 1t and Is made to re-
volve al a high velocity by some mechanical
| force such steam. Suppose this speed
Is lUOO revolutions per minute, which is not
unusual, and that We have 500 wires on
this immature, then We will have as the
armatu,e revolves, what would be equivalent
to single wire cutting across all the lines of
magnetic force SOC, 900 times each minute
The magnet generally surrounds the arm
allure and these magnetic lines OF force are
shooting through the armature in con-
tinuous stream at an uncomfortable velocity.
All the wire conductors on the revolving
armatUre as they move through these lines Of
magnetic force are constantly picking up their
little share Of electricity AID unloading it by
means Of Ingenious mechanical devices con-
Meeting with the conducting wire that leads
from tie dynamo and receiving the returning
electricity ON another wire leading back into
the dynamo.
One Of natures wonderfully mysterious laws
Causes sctt iron to become magnetic when sur
rounded by a current of electricity. In the
ordinary dynamo this law is of the greatest
utility. AS the electrical current Is being col
iected by the revolving armature it Is led
| around the magnet and thus the magnetic
germ is quickly changed into mighty force,
again feeding the armature which transfer nus il
/ from m In electrical fnrce