Montpelier examiner. [volume] (Montpelier, Idaho) 1895-1937, 1912-01-26
THE GENERATION And APPlI-
CATION OF ELECTRIC POWER
BY ARTHUR JOBsoN

If a body weighing 1000 pounds is
raised to a height of 500 feet above
the earth's surface and held in this
position it is said to possess potential
energy with reference to the earth's
surface. The quantity of potential
energy which it possesses at this
height is equal to the amount of work
done in raising the body, which, in
this particular case, is 100000 foot
pounds. Evidently the body in NOV
ing back down to the earth can be
made to do this amount of work.
Let us assume that a rope is attached
to the weight while it is being held
at the height of 800 feet, and that this
rope is passed over a grooved pulley
just above the weight to the earth's
surface below the weight. Let MS
further assume that about 500 feet of
this rope is wound on drum so that
as the weight descends the drum will
rotate. Now If we permit the weight
to descend at the rate of 100 feet per
minute it will be doing work at the
rate of of 100000 foot-pounds per min
ute Q,0OO multiplied by 1907, and it
will generate about H. P. If we
neglect the weight of the rope all this
power will be delivered to the drum
upon which the rope is wound. This
is an example of the power which may
be generated by body of definite
weight descending from higher to
a lower elevation, and is the principle
upon which power is generated from
water. The water must of course be
"harnessed" differently before it can
be made to do the work
The heat of the sun eyaporates
water daily from the earth's surface.
This water rises in the form of
moisture, and at certain elevations
above the earth's surface it is con-
densed and falls in the form of rain
or snow. That portion of the water
which is deposited on the higher ele
vations of the earth's surface exists
in the form of potential energy with
respect to the lower elevations, and
possesses the quality of doing work,
Just as the weight of 1000 pounds
| 500 feet above the earth's surface
, could be made to do work. The heat
of the sun does work in raising the
water to the higher elevations and
therefore man, in utilizing watei
power, obtains a portion of the suns
heat energy. twill now be seen that
In case of water power developments
the light derived from electric lamps
! and the heat derived from electric
heaters is simply the suns light and
heat delivered to us through various
, transformations.
In engineering practice the uni
2 volume of water is usually taken a,
] the cubic foot, and the unit of tiInt
, in measuring water as the second
, Hence the unit of flow or discharg,
! would be the product of these TIVE
e quantities, or the cubic foot per sec
: ond. TO obtain clear idea of cubi
: foot of water flowing per second lie
p us assume q fiume or channel of an.
p length, having depth of exactly on
. foot and width of one foot. Suppos
this fiume is running level full o
r water, and that the mean velocity j
i one foot per second. The fiume viii
= then be carrying exactly one cubi
n foot Of water per second, or what i
e commonly termed, one second foo
o A velocity of one foot per secon
n means that II . float was placed !
tfa ranHing water 1t would move