The suburban citizen., 1900-06-23
POWERINA 0'C0AL
WORK THAT CAN DE- GOT OUT or A
HANDFUL OF BLACK DIAMONDS.

III YOU raise $50 pounds lJO leet
high in one minute, you have done
33, 900 foot-pounds of work in a min
ute. and this is called one-horse
power. When we have weight, dis.
tance and time we have the three ele-
ments which constitute a measure of
work by which two men or two horses
or two machines can be compared.
This had been done for some time be-
fore men began to realize that there
was a distinct relation between such
units Of work and quantities Of heat.
Count Rumford FIRST attempted to
measure this by determining the guam
tity of heat which was involved in the
boring of a cannon at the arsenal at
Munich, Germany. Other observers
followed him, and finally adopted
what is known as the mechanical
equivalent of heat, namely, 77S foot
pounds.
When the chemist wants to de-
termine the power contained in one
pound Of coal, he simply crushes his
coal to a fine powder and takes a
small quantity of it, which he care
fully weighs, and by chemical means,
burns under water. Having previ-
ously determined the exact weight
and temperature of this water, he
finds its temperature after this guam
tity of coal has been burned in it,
and then figures out that if the small
pinch of coal which he burnt adds so
much temperature to the small guam
tity of water, pound of the coal will
add a proportionate quantity to a
larger weight of water.
Let us, for the purpose Of what
follows, take pound of what we will
call average coal, containing, say,
10000 heat units. This would be
somewhat smaller in size than a mans
fist. Il we could burn this pound OF
coal completely and entirely under
water and let all its heat go into the
water, we could raise the temperature
of 625 pounds of water sixteen de-
grees.
Picture to yourself that you have a
bathtub five feet long, two feet wide,
and filled one foot deep with water,
and that this water has a temperature
of sixty-four degrees. If the pound
of coal could be completely burned in
that water and all the heat thereby
involved could be impaired to this
body of water, the later would have
become sixteen degrees hotter, i. O.,
it would be comfortable bath at
eighty degrees Fahrenheit. This
does not seem like very much work,
but it gives a fair measure of the
quantity of heat which slumbers in
the lump of coal.
The TO-, 900 heat units in this one
pound of coal which we found suti-
eient to warm our bath, if expended
in mechanical work, would give us
236 horse power. Watt, the father of
the modern steam engine, found that
a strong brewers horse could, during
eight hours, do work sufficient to
raise $50 pounds 100 feet high in one
minute, and hence he called this
quantity Of work performed in this time
one horse power. We must remem-
Der, however, that the horse will not
be raising constantly, for after eac h
hoist the rope and hooks must be
again lowered, so that scarce four out
of the eight hours are actually spent
in the active work Of hoisting. We
have, therefore, hidden away in this
one pound of coal the full days work
of strong Percheron horse,
The snowfall in winter often seri-
ously impedes travel on city streets,
as we'll as on railways. This has led
inventors to study out and patent a
number of devices intended to melt
away the snow. The fallacy of this
mode or proceeding becomes apparent
as soon as we figure out what pound
of coal can do in that way. 1t takes
142 heat units to melt one pound OF
ice or snow when this ice or ,snow is
already at thirty-two degrees. If it is
colder, it will take as many more heat
units as are required first to bring
the snow to this melting temperature,
known as the freezing point. There
fore, when the snow is just ready to
melt, the heat in the pound of coal is
Just sufficient to melt seventy-one
pounds of snow. This is less than
one-third of an ordinary cart load.
But we have just seen that this pound
of coal carries within it the power of
236 horses, each of which could cas-
lily pull thirty times as much snow, il
loaded in a wagon, as this one pound
of coal can melt.
Again, the 236 horse power of po-
tential energy which we know to be
slumbering in this pound of coal
would do the work of an express loco
motive for one-dfth of minute. In
other words, it is enough to haul a
train of eight cars, including Pullman
sleeping cars aud dining cars, at the
rate of fifty miles an hour one-sixth
of mile. 1t is enough to haul a
train at the rate OF nine miles an hour,
including the grip car, the trailer, and
it's quotum of moving cable, distance
of nearly two miles; and it is enough
also to pull an electric motor car.
loaded with passengers, at the rate Of
ten miles an hour, two and one.half
miles.
oL 80 oa,,-evo l, ,,o,,ot. -,