No artist would have dared to draw a walking figure in attitudes like some of these. The swinging limb is so much shortened that the toe never by any accident scrapes the ground, if this is tolerably even. In cases of partial paralysis, the scraping of the toe, as the patient walks, is one of the characteristic marks of imperfect muscular action. Walking, then, is a perpetual falling with a perpetual self-recovery. It is a most complex, violent, and perilous operation, which we divest of its extreme danger only by continual practice from a very early period of life. We find how complex it is when we attempt to analyze it, and we see that we never understood it thoroughly until the time of the instantaneous photograph. We learn how violent it is, when we walk against a post or a door in the dark. We discover how dangerous it is, when we slip or trip and come down, perhaps breaking or dislocating our limbs, or overlook the last step of a flight of stairs, and discover with what headlong violence we have been hurling ourselves forward. Two curious facts are easily proved. First, a man is shorter when he is walking than when at rest. We have found a very simple way of showing this by having a rod or yardstick placed horizontally, so as to touch the top of the head forcibly, as we stand under it. In walking rapidly beneath it, even if the eyes are shut, to avoid involuntary stooping, the top of the head will not even graze the rod. The other fact is, that one side of a man always tends to outwalk the other, so that no person can walk far in a straight line, if he is blindfolded. The somewhat singular illustration at the head of our article carries out an idea which has only been partially alluded to by others. Man is a _wheel_, with two spokes, his legs, and two fragments of a tire, his feet. He _rolls_ successively on each of these fragments from the heel to the toe. If he had spokes enough, he would go round and round as the boys do when they "make a wheel" with their four limbs for its spokes. But having only two available for ordinary locomotion, each of these has to be taken up as soon as it has been used, and carried forward to be used again, and so alternately with the pair. The peculiarity of biped-walking is, that the centre of gravity is shifted from one leg to the other, and the one not employed can shorten itself so as to swing forward, passing by that which supports the body.