This section is from the book "Human Physiology For The Use Of Elementary Schools", by Charles Alfred Lee. Also available from Amazon: Human Physiology, for the Use of Elementary Schools.
14. We see that it requires a long time for children to learn to walk securely. The reason is, that the base of support for the body is small; being only the space between the feet and that on which the feet rest. The larger the base, the easier it is to maintain an erect position ; so that persons with small feet do not stand as firmly as those with large ones. This accounts for the difficulty of standing on our toes, or of walking on a rope. It is practice and instinct which teaches children where to place their feet in order to be most secure when erect; their muscles also are still weak, for want of exercise.
15. Walking consists in a succession of steps. We first balance the body on one foot, then bending the opposite foot on the leg, and the leg on the thigh, we bend the thigh on the pelvis, and so shorten the limb. In this way the leg is brought forward, and the foot is then brought to the ground resting first on the heel; the body is then partially rotated on the head of the thigh bone, and the other leg is raised, bent, and carried forward in the same manner, and the foot placed in advance of the other. The legs thus act as levers to propel the body along, and the longer the levers the more rapid will space be measured over.
16. The utility of walking excels that of all other modes of progression. While the able pedestrian is independent of stage coaches and hired horses, he alone fully enjoys the scenes through which he passes, and is free to dispose of his time as he pleases. To counteract these advantages, greater fatigue is doubtless attendant on walking; but this fatigue is really the result of previous inactivity; for daily exercise, gradually increased by rendering walking more easy and agreeable, and inducing its more frequent practice, diminishes fatigue in such a degree, that very great distances may be accomplished with pleasure, instead of painful exertion.
17. The power of walking great distances, without fatigue is unfortunately in this country a rare accomplishment. A good walker will do six miles an hour, for one hour, on a good road. If in good training, he may do twelve miles in two hours. Eighteen miles in three hours have been achieved, though rarely. At the rate of five miles an hour, pedestrians of the first class will do forty miles in eight hours, and perhaps fifty in ten. Captain Barclay walked 180 miles without resting ; and also 1000 miles in 1000 successive hours.
18. In the act of leaping, the whole body is raised from the ground, and for a short time suspended in the air. It is performed by bending the head upon the body, the body on the thighs, these on the legs, and the legs on the feet. The feet do not stand firmly on the ground, as in walking, but the heel is raised, or perhaps slightly touches the ground. The muscles are all in a state of flexion. They are suddenly contracted at the same instant; the consequence is, that the feet are raised from the ground and carried forward, and the body with them, until it is brought to the earth by the force of gravitation. The distance passed over, is in proportion to the power and suddenness with which the muscles contract.
19. The muscles which form the calf of the leg, act with the greatest power in leaping, as they have to raise the whole body. Their great strength is shown by raising the body upon the toes, together with a large additional weight; and this power is not only owing to their great size, but also to the manner in which they are inserted into the heel, thus having the advantage of the long arm of a lever.
20. The muscular powers exhibited by many small ani mals and insects is astonishing. Small animals can leap much farther than large ones, according to their size. The flea and the locust leap two hundred times their own length, as if a man should leap twelve hundred feet high. Others leap three hundred times their length, and if man was as strong in proportion, he ought to leap more than a quarter of a mile. We read of an English mechanic, who made a golden chain as long as the finger, with a lock and key, which was dragged by a flea, and of another flea dragging a silver cannon on wheels, that was twenty four times its own weight. This cannon was charged with powder and fired without the flea seeming to be alarmed. A cockroach, or an ant is six times as strong, for its size, as a horse ; and, if an elephant were as strong in proportion, he would be able to tear up rocks and level mountains.
21. Hopping is merely leaping on one foot. As but half the muscular power is exerted, a man ought to be able to leap twice as far as he can hop. Running consists of a succession of low leaps, performed by each leg alternately. It differs from walking, in the body being thrown forward at each step, and the hind foot being raised before the fore foot touches the ground. A person cannot stop running instantly, as he can walking, because his velocity is so great as to carry him forward a certain distance, whether he uses his muscles or not, and thus occasions him to fall.
22. The practice of running may be carried to a great degree of perfection. A quarter of a mile in a minute is good running; and a mile in four minutes, at four starts, is excellent. A mile was perhaps never run in four minutes; but it has been done in four minutes and a half. A mile in five minutes is called very good running; two miles in ten minutes is but rarely accomplished. Ten miles an hour is done by all the best runners. Forty miles, in four hour3 and three quarters has been done by one individual. Some Indians, it is said, will run at this rate for several hours, but it is very doubtful.
23. Swimming is very much like leaping ; at least the same muscles are brought into action in the lower limbs. While the hands are brought to a point before the head, the legs are drawn up and suddenly extended, as in leaping. By the resistance of the water, the body is projected forwards. The hands are now carried, with a circular motion, the palms being turned outwards, till they reach the sides of the body, and thus the impulse through the water is kept up by a constant succession of these movements. A boat is propelled on the same principle. Indeed the body may be compared to the boat itself, and the hands and feet to the oars. A good swimmer ought to make three miles an hour.
24. The human body is very nearly of the same specific gravity as water; that is, it is of the same weight as a body of water of the same bulk. Dr. Franklin says if a person avoids struggling and plunging, he may lie on his back with his mouth and face out of water, without difficulty, even if he cannot swim. As swimming therefore, is a highly useful art, and an agreeable and healthy exercise, it should be made a necessary part of the education of boys.
25. The importance of gymnastic exercises will only be questioned by those who are not aware that the health and vigour of all the bodily organs depend on the proportioned exercise of each. Such exercises ensure the development of all the locomotive organs; and they prevent or correct all the deformities to which those organs are liable. They are the best calculated to produce strength and activity, and to bestow invariable health. At the same time they confer beauty of form, and contribute to impart an elegant air and graceful manners.