Were our strength in proportion to this, we could play
with weights equal to ten times that of a horse.
This seems, again, great kindness in Nature to the smaller animal. But
all these calculations leave out the elementary mechanical law: "What
is gained in power is lost in time." The elevation of a ton to a given
height represents an expenditure of an equal amount of force, whether
the labor is performed by flea, man, or horse. Time supplies lack of
strength. We can move as much as a horse by taking more time, and can
choose two methods--either to divide the load or use a lever or a
pulley. If a horse moves half its own weight three feet in a second,
while a June-beetle needs a hundred seconds to convey fifty times
its weight an equal distance, the two animals perform equal work
proportioned to their weights. True, the cockchafer can hold fourteen
times its weight in equilibrium (one small June-beetle sixty-six times),
while a horse cannot balance nearly his own weight.
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