Secondly, the obliquity with which the tendons run to their insertions is increased by this arrangement; and the velocity of the movements to which they minister is increased also. True, a loss of strength is involved in such a disposition, but the gain in velocity is of more importance. If (to refer again to the diagram, fig. 15) the tendon ran in a straight course from the front of the leg to the great toe, the angle at which it joined the toe would enable it to act with more strength; but the movements connected with it could not be so quick as they now are.
We find in the construction of the human frame many instances in which strength is sacrificed to rapidity of movement in this and other ways. Scarcely any conceivable amount of strength, for instance, would be an adequate compensation for a loss of that celerity of movement of the hand which enables us to strike a blow and drive a nail. No wonder, therefore, that strength is here sacrificed to obtain celerity. And the same principle holds good for other parts.
The length and direction of the heel affords a good illustration of the principle of which I am speaking. When the heel-bone runs out to a considerable distance, and nearly straight, behind the ankle, as it does in some of the lower animals and in the inferior races of mankind, it presents a better leverage to the calf-muscle, which is, then, enabled to raise the ankle with a less amount of effort; but there is proportionately less velocity. Accordingly, in the more perfectly formed foot, such as we find it in the higher races of mankind, the heel-bone, instead of running out backwards, descends very obliquely, almost vertically.
In this instance, the loss of strength, which is thus incurred for the purpose of acquiring celerity in movement, is usually compensated for by the greater development of the calf-muscle. Hence the high heel and the well-developed calf go together; and, like most of the other features of good bodily formation, they are, on the whole, best marked in the nations which are endued with the highest intelligence, and which are, in this way, physically, as well as mentally, qualified to occupy the foremost places in the human family. Thus, we may mark a relation between the heel and the brain; and, as the comparative anatomist is able by the inspection of a bone to trace out the skeleton to which it belonged, so might it be possible for the human anatomist, by observing minutely the peculiarities of the heel and the other features of the foot in any particular race of men, to form some estimate of the capacity and conformation of the skull, and thereby, of the amount of intelligence.
Contrast the foot and leg of the European (fig. 16), as represented in the drawing reduced from the Farnese Hercules, with those of the Negro (fig. 17), the drawing of which was taken from a native of Sierra Leone. In the former the leg is plump and the calf well developed; the foot is compact and well arched; the heel descends nearly vertically; and the inner ankle stands clearly out and is raised high above the ground. In the Negro the leg is thinner and the calf is not so well defined; the foot is long, flat, and sprawling; the heel is more horizontal; and the inner ankle does not show clearly, and almost touches the ground.
Fig. [16].
Fig. [17].
