Wood County reporter. [volume] (Grand Rapids [i.e. Wisconsin Rapids], Wis.) 1857-1923, 1873-07-10
The Horse Power and the Power of
the Horse.

difficulty in reconciling the definition of
horse pow er, as given by writers on en-
cheering subjects, with their own knOWl-
edge of the power of the horse. There
are three terms which we must define with
precision, before attempting to place the
subject before our readers in such man
ner as shall give them an accurate notion
of the meaning of the term first referred
to.
Force is defined to be anything which
produces or tends to produce motion, or
ehange of motion, in bodies. The force
OF gi~vitation, of electrical and magnetic
attraction, of heat repulsion, of steam
pressure, and of compressed spring, are
illustrations 1t is measured bv the weight
which Will counterpoise it.
W0rk is force acting through space. and
is measured by multiplying the measure
of the force by the measure of the space.
a force which overcomes resistance of )
pounds through space Of 7 feet, does 30
foot pounds" Of work" A weight of
tons is raised feet, or so inches, by the
expenditure of 10 foot pounds" or its
equivalent, 1870 Inch tons''
Po1cer, as the term is only properly used
by engineers, is the amount of work done
in any given example, in some known
time. Its unit is called the "horse
power" Thus, a machine doing $4,000
foot pounds of work in minute devel-
| opes one horse power. The same ma
chine, working in the same manner, would
do $50 pounds OF work in each second, or
10000 foot pounds during each hour that
it might be continuously worked The
horse power, therefore, is a rate of work
y horse cannot usually exert great
power; but the term was first introduced
VT =,
is a matter Of no consequence so long as
it is we'll understood what that value is,
engineers have not thought it advisable to
change it. The actual power of horses
| varies immensely, being sometimes more
| than horse power, and often much less
The average power of a good draft horse
is about three quarters of a horse power,
| but 1t can only be sustained about eight
| hours day. The same horse drawing in
| gin or mill would exert power which
would aN erage for eight hours work tritie
more than a half horse power. An OK is
said to have about two thirds the power
| OF a horse, or to be capable of exerting
about half horse power. The OK can
pull as heavy a load as the horse, but
moves more slowly, and hence does less
work in given time, and rates less horse
power.
The mule pulls about one half the load
of strong draft horse, at about the same
speed. He may therefore be rated at 4
OF 24-ss Of a horse power. The ass rates
at about a of the power of the horse, or
ID of 54-3-16 horse power
On direct pull the average lift which
| a horse can exert in steady work over
single pulley is about 1870 pounds. The
maximum is probably double this figure.
p,nf II ~,
"Traction Engines" of which we gave an
abstract some months ago, says: expert
ments made by Captain Robert Merry, at
the Jackson Iron Mine, Negaunee, Mich,
and the observations and experiments of
the writer, indicate the maximum direct
traction force of a good horse to be about
$50 pounds" This weight, raised at the
rate Of $50 feet per minute or about three
miles per hour. would give 250X250.33,-
OOO-19, nearly two horse power for the
power Of such an exceptionally strong ami
NAL; but we should not expect any horse
to keep up such eXertion for more than a
very short space of time. The estimates
before given were for average work, kept
up eight hours day for days and weeks
together.
British engine builders use a term, in
giving the size Of steam engines, which is
known as nominal horse power and is
much smaller than the actual power of
the engine, which is usually known as the
indicated horse power" or the dynamo
metrical horse power" according as it is
determined by the indicator or the dyna-
mometer Thus the engines of the British
iron clads, Devastation and Thunderer, if
driven at the low speed and with the low
steam used in the time Of James Watt,
would be of about 800 horse power. They
still are said to be of 800 nominal horse
power, but the Thunderer, in her recent
trial, developed 800 indicated horse pow
err. In this country, this unfortunate and
confusing application of the term nom
inal' horse power is almost unknown,
and we indicate the size of an engine by
specifying its diameter of cylinder and
length Of stroke. The engines of the
Thunderer, for example, have two cylin-
ders for each of her twin screws, which
are SO inches diameter and ~ inches
stroke-.Scientifc american.
TO Destroy the Cabbage Worm.-l
have been entirely successful during the
past season with the following: DILUTED
mackerel brine applied on and around the
plants three or four times per week until
the cabbages begin to head. In my gar
den all that | treated in this way made
good sound heads, and others in the same
patch were destroyed. "-RuratN Ne" York