Year: 1877

How best to utilize human labor, and
Mt the same time to produce the least
fatigue, is one of those interesting prob
lens in industrial mechanics which every
inventor of machines based on man
power rs n motor is called upon to con-
slider, and to which every employer of
men for the sake of their brute muscular
strength is obliged to give some atten-
ton. It is a common error to believe
that, in order to produce given amount
of work, q man always expends given
amount of power, and to recognize this
is the first step toward a correct estima-
ton of mans muscular capability.
Appropriate rests are absolute necessi-
ties to the human machine, and it is by in
termittent, not continuous, effort that its
best work is produced. One man labor
ing ten hours and taking intervals of re-
pose will produce more force and accom-
plish more work with less fatigue than
another laboring eight hours with shorter
or less frequent rests, the actual time
spent in working in both cases being
equal. But on the other hand, during
the periods of absolute work regularity
is necessity, fact clearly shown by the
government of soldiers on long marches,
where the drum to which the feet keep
time is wonderful agent for repressing
fatigue, simply because it insures regu-
larity Of motion. So also in rowing in a
long race experience has proved the ad-
vantage of Il clockwork regularity of
stroke with brief breathing spell be-
tween each pull. In fact it appears that
men will naturally fall into this cadence,
us witness the blows delivered by labor
ers with sledge hammers upon rock drills,
and the peculiar timed "hup" which
each will aspirate rs his implement falls,
or the tendency which sailors have to
break into q cadenced singsong when
pulling a standing haul OH a rope. A
more curious instance in this regard is
found in the power of dancing +; nothing
but the repeated rests and the regular
movements will explain the ability OF
women, to whom ordinarily walk of a
mile in length is severe task, to dance
during n period of five or six hours, and
this at q time when nature is most ex-
hausted, owing to deprivation of sleep.


The best application man can make
of his power is through his legs, for the
muscles of those members are not only
absolutely but relatively stronger than
those of the arms. In other words, after
work, the fatigue producedin both sets OF
muscles being equal, the leg muscles will
have performed more useful labor than
those of the arms. And further, the
nearer we initiate natural movement
the better do we apply the power. there
fore walking motion of the legs, at q
velocity equal to that of m ordinary gait,
and applied to levers, is probably the
most ef1icacious application OF human
force for steady work.


As to the absolute power of man ex-
pressed in pounds to be lifted or in SINH
lar terms, exact data are obviously i'm
possible, even for IN average individual.
An interesting series of experiments were
conducted on this subject some. time ago
in France, and these, We believe, give a
fair approximation. The heaviest load a
man of strength can carry for short dis
tance is placed at 319 pounds All q man
can carry habitually-as q soldier his
knapsack- walking on level ground is 132
pounds, and this is an extreme load, We
should Judge. Or he can carry on aggre-
gate of ], ,51S pounds over 5000 feet as q
days work, under like circumstances. II
he ascend ladders or stairs-as do hod
carriers-then he can carry but 121
pounds continuously, and his days work
cannot exceed 1882 pounds raised 5000
feet high. With regard to the effort and
velocity which man can produce by
pulling or pushing with his arms, it has
been found that, under the most favor
able circumstances and for continuous
work, an effect exceeding from 26 to SO
pounds raised from 1.S to 81 feet per
second cannot begained, and this is equal
to about horse power.