nal biped.

Considering, as it is proper to do, that in a condition of health each
separate biped and each individual leg is required to perform an equal
and uniform function and to carry an even or equal portion of the weight
of the body, it will be readily appreciated that the result of this
distribution will be a regular, evenly balanced, and smooth displacement
of the body thus supported by the four legs, and that therefore,
according to the rapidity of the motion in different gaits, each single
leg will be required at certain successive moments to bear the weight
which had rested upon its congener while it was itself in the air, in
the act of moving; or, again, two different legs of a biped may be
called upon to bear the weight of the two legs of the opposite biped
while also in the air in the act of moving.

To simplify the matter by an illustration, the weight of an animal may
be placed at 1,000 pounds, of which each leg, in a normal and healthy
condition, supports while at rest 250 pounds. When one of the fore legs
is in action, or in the air, and carrying no weight, its 250 pounds
share of the weight will be thrown upon its congener, or partner, to
sustain. If the two legs of a biped are both in action and raised from
the ground, their congeners, still resting in inaction, will carry the
total weight of the other two, or 500 pounds. And as the succession of
movements continues, and the change from one leg to another or from one
biped to another, as may be required by the gait, proceeds, there will
result a smooth, even, and equal balancing of active movements, shifting
the weight from one leg or one biped to another, with symmetrical
precision, and we shall be presented with an interesting example of the
play of vital machanics in a healthy organization.

Much may be learned from the accurate study of the action of a single
leg. Normally, its movements will be without variation or failure. When
at rest it will easily sustain the weight assigned to it without
showing hesitancy or betraying pain, and when it is raised from the
ground in order to transfer the weight to its mate it will perform the
act in such manner that when it is again placed upon the ground to rest
it will be with a firm tread, indicative of its ability to receive again
the burden to be thrown back upon it. In planting it upon the ground or
raising it again for the forward movement while in action, and again
replanting it upon the earth, each