Swimming, under proper superintendence, ought to be universally enforced. The exercise accompanying it serves in most cases to counteract the depressing action of the cold water; but it is important in all cases to attend to certain rules. The immersion should not be prolonged; the body should be warm at the time of entering the water; and the bath should not be taken until about two hours after a meal; nor after prolonged fasting, as before breakfast. =Personal Cleanliness.=—Personal cleanliness involves not only attention to the skin, which we have already considered, but to the hair, nails, mouth, and other parts of the body. The _hair_ ought to be carefully brushed and combed, but it is not desirable to use soap to it as often as to the skin. Soap removes the sebaceous secretion from the hairs, and renders them dry and brittle. Artificial pomades are, as a rule, unnecessary. The _nails_ should be cut square, and not down at the sides. It is hardly necessary to say that they should be kept clean: they may convey serious infection. The _mouth_ and all mucous orifices should be kept scrupulously clean. A fœtid breath is not uncommonly due to the discharges from carious teeth, or to the decomposition of food which has been allowed to accumulate in the cavities of teeth. Such decomposing matters when swallowed, are apt to produce indigestion; and this also occurs from imperfect mastication of food by the bad teeth. It is important that the _teeth_ should be frequently cleansed, and that all carious teeth should be “stopped” at an early period, and tartar and other accumulations removed. Whether bad teeth, which are so extremely common, are due to the drinking of very hot liquids, or to the fact that the more perfect cooking of food gives less healthy friction to the teeth, is doubtful. Whatever the cause, by keeping the mouth thoroughly sweet and clean, and by having the carious teeth stopped as soon as discovered, their vitality may be greatly prolonged. Teeth should be periodically inspected by a competent dentist. Irregularities of the teeth may be corrected, if they receive early attention. Carious “milk-teeth” should receive attention from a dentist, as well as the permanent teeth. =General Cleanliness.=—Next to cleanliness of the skin, that of the _apparel_ is most important. There is a general preference for colours “that do not show the dirt”; the fact that it is still there, though not seen, being partially ignored. Changing of apparel is commonly confined to underclothing. It is forgotten that vests, trousers, dresses, etc., acquire a large amount of dirt and organic matter, and ought to be changed and well aired at intervals.