The disadvantages arise from the fact that the temperature of the water is very much below that of the body, so that there is a greatly increased conduction of heat from the body, and, unless this loss is made good by exercise, there is very great danger of a chill. In most persons a prolonged stay in cool or cold water produces a liability to cramp.

During the month of August the temperature of the ocean reaches its maximum of 66.65° F. This is about 32 degrees below the temperature of the body. Upon entering the water the first effect noticed is a sensation of cold; this varies with the susceptibility of the individual, and the difference between the temperature of the water and the surrounding air. The skin assumes the appearance of “goose-flesh,” the face is pale and anxious, and the lips are blue; the pulse decreases in frequency, a sense of oppression is manifest, and there may be spasmodic shivering; that is, the first effect of immersion is to cause a contraction of the blood-vessels of the surface of the body. This should be quickly followed by a secondary reaction, in which there is a sensation of warmth, a quickened pulse, and an increase of energy. When, by taking the proper precautions, this reaction does not occur, it is a contraindication to sea-bathing and swimming.

If the immersion has been too prolonged, there is a second sensation of chilliness, a signal that the bather must leave the water at once.

The best time for bathing is between eleven o’clock in the morning and four in the afternoon, depending on the tide. No one should go into the water within two hours after meals, nor should she on leaving the bath proceed at once to the table, since digestion draws the blood from the periphery to the stomach, and to eat immediately after bathing is to lose most of the benefit of the saline treatment.

All should avoid cold-water bathing when fatigued, and swimmers ought to pay especial attention to this point, on account of the demand they are going to make on their muscular system; and on no account must one enter the water when in a perspiration; a moderate walk along the shore should be taken until the perspiration has subsided. These precautions are of the highest importance, and disregard of them may prove fatal.

Enter the water quickly until it reaches the waist, then plunge headlong, or cover the body to the neck. Care should be taken to wet the chest and abdomen immediately on entering the water, since these parts are the most sensitive to the impression of cold.

Every one should learn to swim, and those who cannot must move the arms and legs about vigorously. The duration of the bath should depend on the state of the health of the individual, on the state of the weather, and on whether the water is rough or calm. The average duration of the time spent in the water should be from three to fifteen minutes, the latter being the maximum time for any one. No benefit will accrue from spending a longer time than this in the water, and much harm may result.

The sea-bath should be followed by moderate exercise, in order to insure a perfect reaction, and to aid in expending the superfluous energy which sea-water imparts.

Swimming and sea-bathing should be avoided by persons who have weak hearts and a poor circulation, in whom the reaction after a plunge into cold water is never well established. Also by persons with heart or kidney disease, and by all feeble and old persons.

Persons with feeble constitutions, but with no actual disease, as in various forms of nervous disorders, insomnia, etc., generally derive marked benefit from sea-bathing.