Year: 1877

at 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 as 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. 1t is common error to believe
that, in order to produce a given amount
of work, a man always expends a given
amount of power, and to recognize this
is the first step toward a correct estima-
ton of a 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 a necessity, fact clearly shown by the
government of soldiers on long marches,
where the drum to which the feet keep
time is a 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 adj
vantage of clockwork regularity of
stroke with brief breathing spell be-
tween each pull In fact it appears that
men will naturally fall into this cadence,
as witness the blows delivered by labor
ers with sledge hammers upon rock drills,
and the peculiar timed "hup" which
each will aspirate as his implement falls,
or the tendency which sailors have tc
break into cadenced singsong when
pulling standing haul on 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 o.
women, to whom ordinarily walk of {
mile in length is q severe task, to dance
during a period of five OF six hours, ant
this at q time when nature is most ex
hausted, owing to deprivation of sleep.


The best application a man can make
of his power is through his legs, for the
muscles of those members are not only
absolutely but relatively stronger thai
those of the arms. In other words, afte
work, the fatigue produced in both sets o
muscles being equal, the leg muscles vii
have performed more useful labor THAI
those of the arms. And further, tn


nearer we initiate q natural movemen
the better do we apply the power. there
fore a walking motion of the legs, at


ua1DnItxr an1a1 IN tho Of oY,p
and applied to levers, is probably tn


most efficacious application of humal
force for steady work.


AS to the absolute power Of a man eX
pressed in pounds to be lifted or in simi
lar terms, exact data are obviously i'm
possible, even for an average individual
An interesting series of experiments wer
conducted on this subject some time ag


in France, and these, we believe, give


fair approximation. The heaviest load


man of strength can carry for u short dis


tance is placed at 319 pounds. All a ma


can carry habitually-as a soldier hi


knapsack-walking on level ground is 13
pounds, and this is an extreme load W
should judge. Or he can carry an aggrt
gate of l, 518 pounds over 5000 feet as
days work, under like circumstances.


he ascend ladders or stairs-as do ho
carriers-then he can carry but 12
pounds continuously, and his days wor
cannot exceed l, 232 pounds raised 800
,; feet high. With regard to the effort an
velocity which man can produce b
pulling or pushing with his arms, it ha
been found that, under the most favol
able circumstances and for continuou


work, an effect exceeding from 26 to 8
,, pounds raised from 1.S to 81 feet pc
second cannot be gained, and this is equi
to about / horse power.