Evening star., 1922-05-21
\ Ut to an electrical engineer a
question concerning the force
with which he deals and gen.

- question concerning tne 1ofce
with which he deals and gen.
orally he seizes a pencil and
paper and begins to draw a picture.
/ The picture is graphic representa-
| tion of an idea One must compre-
hend the idea before being able to
Electricity is far more definite
thing in the way Of science than is
steam power. The public has
| learned from constant repetition
that about 80 per cent of the energy
| liberated by burning coal to operate
a steam engine IL wasted. In an
electrical machine the waste is far
can be generated can be measured
with far greater accuracy. Electric
| generators are machines to trans
| form mechanical power into cleo
trical power. In other words, they
| generate electric current when
driven by mechanical power. They
are run by steam engines. turbines.
gas engines or some other form of
mechanical power called prime
movers" The generator is construct
ed to transform the amount of me-
chanical power that the prime NOV
er running it supplies. A generator
operated by a ten-horse-power en-
| gine. for instance, will transform
| ten horsepower of energy, less a
small percentage. about 10 per cent.
lost in the process,
ELECTRICAL engineers do hot usu-
ally state that generator
transforms a certain horsepower.
Their measure of energy. or power.
is the kilowatt, which is equal to one
and one-third horsepower. So they
say that the generator transforms
seven and half kilowatts, which is
the equivalent of ten horsepower.
Why should this change in nomen-
| clature be any more confusing than
to say that one inch is equal to two
| and one-half millimeters?
Mention the action of electric cur
rent to a novice. and he Immediately
assumes a look of blank perplexity.
| Yet the fundamental facts about
electric current are extremely sim
pie. An esectric current will not
| move unless it can move in a COM
| plete circuit and get back where it
| came from. This is why IT is safer
| for a man handling an electric cur
| rent to work with one hand behind
i his back. He is then not likely to
| touch 1t in two places and thus
complete a circuit through himself.
Electric current may be said to have
| exactly the same sort of ''intelli-
| gence" as a child playing "puss-in-
| the-corner." The child will not leave
| the corner it occupies until it sees
| q corner free for it to 60 to.
BY likening the electric circuit to
the piping system which leads the
water to a wash basin and away from
it to the sewer it is possible to grasp
this idea, at the same time noting the
| difference in the action of the electric
current and of the water. In the case
of electricity, if you open the faucet
the electricity will flow only if the
discharge pipe is free all the way, and
lit has the power Of finding this ou,
| instantly, even if the obstruction in
the, discharge pipe is very far away
In other words, an electric current
iiacts physically like one continuous
piece of material, such as a hoop OF
an endless chain. one part of which
moves.
You cannot revolve one part OF .
hoop without revolving the whole
hoop. You cannot move one part OF
an endless chain without moving the
whole chain. In telegraphing from
the electric current is precisely simi-
lar to what it would be IL you had a
long chain reaching that distance and
back, and you pulled upon il inter.
4 mittently to make the dots and
dashes. Only. instead Of pulling on
the chain. you break and close the
lelectric circuit. This, can be done al
any point along the line. and the ef.
feet is apparent at any other place oil
at any number of places simulta.
neously. Sometimes he return part
of the chain is by a second electric
iwire, and sometimes thereturn is made
Through the earth. And when the cir
cult is broken at any point on the
line the current stops everywhere. ts
start again when the break is closed
J.. X ~
lDUT how does the current in Bos-
ton know that the circuit is
broken In San Francisco? This bring,
us TO one Of the really remarkable
facts about electric current 1t trav-
els at the rate OF two hundred thou
sand miles a second. and, can. 30 q
tspeak. "see ahead" this distance
which 10 longer than any. electric cir
cult that has ever been used. So an