Semi-weekly herald., 1912-12-26
SIMPLE EXPLANATIONS
OF ELECTRIC FACTS.

Whenever you ask an electrical en-
gineer a question he seizes a pad and
draws picture. This is getting the
cart before the horse. The picture is
a graphic representation of an idea.
You have to comprehend the idea be-
for you can grasp the significance of
the picture.
Electricity is far more definite
science than that of steam power. The
public has learned from constant repe-
tition that about 80 per cent Of the
energy liberated Ly burning coal to
run a steam engine is wasted. In an
electrical machine the waste is far
less and the amount of energy that is
generated can be measured far more
accurately.
| Electric generators. are machines
TO transform mechanical power into
electrical power. In other words, they
generate electric current when driven
by mechanical power. They are run
by steam engines, turbines, gas eng
ines, or some other form of mechanical
power called prime movers. The gen
orators is constructed to transform
the amount of mechanical power that
the prime mover running it supplies.
A generator run by a ten horse power
engine, for instance, will transform
! ten horse power of energy, less a
small PERCENTAGE (about 10 per cent?
lost in the process. Electrical engi-
nccrs don't usually say that gener-
al1f transform ten horse power. Their
measure Of energy or power is the
kilowatt which is equal to one and
one third horse power. So they say
that the generator transforms seven
and one-half kilowatts, which is the
equivalent of ten horse power. Why
should this change in nomenclature be
any more confusing than to say that
one inch is equal to two and one-half
ccntimeters?
Mention the action of electric cur
rent to neophyte, and he Immediately
assumes look of blank perplexity
Yet the fundamental facts about cleo
trio currents are extremely simple. An
electric current will not move unless
it can move in complete circuit and
get back where it came from. This
is why it is safer for a man working
with an electric current to work with
one hand behind his back. He is then
not likely to touch it in two places
and thus complete circuit through
himself. Electric current may be said
to have exactly the same intelligence
as child playing puss-in-the-corner
The child will not leave the corner it
occupies until it sees corner free for
it to go to. By likening the electric
circuit to the piping system which
leads the water to a wash basin and
away from it to a sewer, it is possible
to grasp the idea by noting the diff
ference in the action of the electric
current and of the water. In the case
of the electricity, if you open the
faucet the electricity will flow only
if the discharge pipe is free all the
way, and it has the power of finding
this out instantly even if the obstruc-
tion in the discharge pipe is very far
away. In other words, an electric
current acts physically like one con-
tinuous piece of material, such as a
hoop or an endless chain, one part of
which will not move unless the whole
of it moves. You cannot revolve one
part of a hoop without revolving the
whole hoop. You cannot move one
part of an endless chain without
moving the whole chain. In telegraph
ing from New York to Chicago the
action of electric current is precisely
similar to what it would be if you
had a long chain reaching this dis
tance and back, and you pulled upon
it intermittently to make the dots and
dashes. Only instead of pulling on
the chain you break and close the
electric circuit This can be done at
any point along the line, and the effect
/ is apparent at any other place or at
any number of places simultaneously
|, Sometimes the return part of the
, chain is by a second electric wire, and
sometimes the return is made through
the earth When the circuit is broken
at any point on the line the current
stops everywhere, to start again wher
the break is closed. But how does the
current in New York know when the
current is broken in Chicago? This
brings us to one of the really re-
markable facts about electric current
. It travels at the rate of 100000 mile.
. second, and can, so to speak, "se'
n ahead this distance which is longei
4 than any electric circuit that has evel
a been used. So an electric curren
stops in less than a second If thu