But this does not
measure the amount of oscillatory motion induced by the respective
pulls. For this, both should operate against a spring.
A small beetle can escape from under a piece of cardboard a hundred
times its weight. Pushing its head under the edge and using it as a
lever, it straightens itself on its legs and moves the board just a
little, but enough to escape. Of course, we know a horse would be
powerless to escape from a load a hundred times its own weight. His head
cannot be made into a lever. Give him a lever that will make the time he
takes equal to that taken by the insect, and he will throw off the load
at a touch. The fact is that in small creatures the lack of muscular
energy is replaced by time.
Of two muscles equal in bulk and energy the shortest moves most weight.
If a muscular fiber ten inches in length can move a given weight five
inches, ten fibers one inch long will move ten times that weight a
distance of half an inch. Thus smaller muscles have an absolutely
slower motion, but move a greater proportional weight than larger.
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