ping distances, and surmounting
obstacles, of proportion apparently overwhelming. Thus the Formica
Herculanea will lift in its mouth, and brandish like a baton, sticks
thicker than itself and six times its length, all the while
scrambling over crags of about the proportionate height of the
Cliffs of Dover, three or four in a minute. There is nothing
extraordinary in this, nor any exertion of strength necessarily
greater than human, in proportion to the size of the body. For it is
evident that if the size and strength of any creature be expanded or
diminished in proportion to each other, the distance through which
it can leap, the time it can maintain exertion, or any other third
term resultant, remains constant; that is, diminish weight of powder
and of ball proportionately, and the distance carried is constant or
nearly so. Thus, a grasshopper, a man, and a giant 100 feet high,
supposing their muscular strength equally proportioned to their
size, can or could all leap, not proportionate distance, but the
same or nearly the same distance--say, four feet the grasshopper, or
forty-eight times his length; six feet the man or his length
exactly; ten feet the giant or the tenth of his length. Hence all
small animals can, _coeteris paribus_, perform feats of strength
and agility, exactly so much greater than those to be executed by
large ones, as the animals themselves are smaller; and to enable an
elephant to leap like a grasshopper, he must be endowed with
strength a million times greater in _proportion_ to his size. Now
the consequence of this general mechanical law is, that as we
increase the scale of animals, their means of power, whether muscles
of motion or bones of support, must be increased in a more than
proportionate degree, or they become utterly unwieldy, and incapable
of motion;--and there is a limit to this increase of strength. If
the elephant had legs as long as a spider's, no combination of
animal matter that could be hide-bound would have strength enough to
move them: to support the megatherium, we must have a humerus a foot
in diameter, though perhaps not more than two feet long, and that in
a vertical position under him, while the gnat can hang on the window
frame, and poise himself to sting, in the middle of crooked stilts
like threads; stretched out to ten times the b