If the seat is too high, the feet do not rest on the floor, and so the girl does not get the proper aid from the legs and feet to maintain an erect position. If the desk is too high, the elbow can rest on it only by curving the spine and raising the shoulder. The work is brought too close to the eyes and causes extra strain. If the desk is too low, the child stoops over it and becomes round-shouldered, and there is a tendency to become short-sighted. The pupil should sit erect with the weight equally borne by both buttocks; the legs should be straight before the trunk, and the feet firmly resting on the floor. The book should be held about twelve inches from the eyes. Spinal Curvatures.-- It should be distinctly borne in mind that lateral curvature of the spine is a distortion of growth. The deformity appears and is developed during the growing years. It is more common in girls than in boys, for two reasons: that at the age when lateral curvature is first seen, girls grow more rapidly than boys; and their muscular system is less well developed. In most early cases the faulty attitudes are clearly the result of muscular weakness. The growth in size has not been accompanied by a corresponding development of the muscles. This condition is most frequently met with in rapidly growing girls, and it is one of the most common causes of lateral curvature. In these cases proper gymnastics are indicated, but they should be prescribed and carried out with much care. It is upon the erectness, suppleness, and strength of the spinal column that most of the power and grace of the body depend. Lack of ventilation is a fertile cause of headache, anemia (or an impoverished condition of the blood in iron and oxygen), and dyspepsia. All these are rare before but common after twelve years of age. Exercise.-- In physical culture the object aimed at should be the symmetrical development of all the muscles of the body. Hence the necessity for bringing every individual muscle into play, at first for its development, and later for its maintenance. The tendency of almost all forms of exercise is to develop some portion of the body at the expense of the rest. The most perfect form of exercise is therefore that one which will most nearly call into play all the muscles of the body. Walking.-- Walking is the only form of exercise which may be said to be universal. In walking the muscles of the chest get little exercise, and those of the spine and abdomen even less. In walking the arms should swing easily at the sides, both from a physiological and an esthetic point of view. If the girl is weak or is unaccustomed to take any exercise, the guide for the amount of exercise taken at any one time must be this: At the first sense of fatigue, stop at once and rest, otherwise positive harm instead of good may be accomplished. The girl who depends on walking for her outdoor exercise should walk at least three miles every day, and walk at the rate of three miles an hour.