It is advisable not to enter the water before digestion is finished. The danger in this case arises less from the violent movements which generally disorder digestion, than from the impression produced by the medium in which these movements are executed. It is not less so when very hot, or quite cold. It is wrong to enter the water in a perspiration, however trifling it may be. After violent exercises, it is better to wash and employ friction than to bathe. Persons of plethoric temperament, who are subject to periodical evacuations, such as hemorrhoids, or even to cutaneous eruptions, will do well to abstain from swimming during the appearance of these affections. _Dress._ Every swimmer should use short drawers, and might, in particular places, use canvass slippers. It is even of great importance to be able to swim in jacket and trousers. _Aids._ The aid of the hand is much preferable to corks or bladders, because it can be withdrawn gradually and insensibly. With this view, a grown-up person may take the learner in his arms, carry him into the water breast high, place him nearly flat upon it, support him by one hand under the breast, and direct him as to attitude and action. If the support of the hand be very gradually withdrawn, the swimmer will, in the course of the first ten days, find it quite unnecessary. When the aid of the hand cannot be obtained, inflated membranes or corks may be employed. The only argument for their use is, that attitude and action may be perfected while the body is thus supported; and that, with some contrivance, they also may gradually be laid aside, though by no means so easily as the hand. The best mode of employing corks is to choose a piece about a foot long, and six or seven inches broad; to fasten a band across the middle of it; to place it on the back, so that the upper end may come between the shoulder-blades, where the edge may be rounded; and to tie the band over the breast. Over this, several other pieces of cork, each smaller than the preceding, may be fixed, so that, as the swimmer improves, he may leave them off one by one. Even with all these aids, the young swimmer should never venture out of his depth, if he cannot swim without them. _Cramp._ As to cramp, those chiefly are liable to it who plunge into the water when they are heated, who remain in it till they are benumbed with cold, or who exhaust themselves by violent exercise. Persons subject to this affection must be careful with regard to the selection of the place where they bathe, if they are not sufficiently skilful in swimming to vary their attitudes, and dispense instantly with the use of the limb attacked by cramp. Even when this does occur, the skilful swimmer knows how to reach the shore by the aid of the limbs which are unaffected, while the uninstructed one is liable to be drowned.