Mineral Point tribune. (Mineral Point, Wis.) 1869-1938, 1873-06-19
The Horse Power and the Power. of
the Horse.

SOME of our readers are finding great
difficulty in reconciling the definition of
horse power, as given by writers on en-
gineering 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
change of motion, in bodies. The force
of gravitation of electrical and magnetic
attraction, of heat repulsion, of steam
pressure, and of compressed spring, are
illustrations. 1t is measured by the weight
which will counterpoise it.
Work 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 a resistance of
pounds through a space Of z feet does 30
"foot pounds" of work" A weight of
2 tons is raised feet, or 60 inches, by the
expenditure Of 10 foot pounds" or its
equivalent 100 Inch tonsn
P0loer, 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 SO, 900
| 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 rate of work.
| A horse cannot usually exert a great
| power; but the term was first introduced
! by James Watt, and since its actual value
| is 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 good draft horse
| is about three quarters of horse power
| but it can only be sustained about eight
| hours a day The same morse drawing in
a gin or a mill would exert power which
would average for eight hours work a trifie
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 load as the horse, but
moves more slowly, and hence does less
work in a 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 a
of As of horse power. The ass rates
at about Il of the power of the horse, or
| Il of 34-3-16 horse power.
On direct pull, the average lift which
a horse can exert in steady work over a
single pulley is about 100 pounds. The
maximum is probably double this figure
Professor R. H. Thurston, in the paper on
Traction Engines" of which we gave an
abstract some months ago, says: Expert
ments made by Captain Robert Merry, at
the Jackson Iron Nine Negaunee, Mich,
and the observations and experiments OF
the writer, indicate the maximum direct
traction force of 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:-333,-
OO0-19, 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 q
| very short space of time. The estimates
! before given were for average work, kept