Page:Popular Science Monthly Volume 23.djvu/817

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add that such clothing, to afford real protection, should be frequently washed. Cotton is next to wool in value, and is preferable to linen, because it gives a gentle excitation to the skin. Silk also has a warm feeling, and might be substituted for flannel in the winter; but it could hardly be worn next to the skin in summer, on account of the excessive heat it provokes. Dr. Balestra insists that it is best for inhabitants of unhealthy countries never to go out without being provided with a woolen cloak or blanket, to be used in case the weather should change. The ancient Romans wore ample over-garments over their tunics, and never put them away. It is no less important to be well covered during the night; and precautions of this kind should be recommended to all who live in a swampy country. We are sometimes astonished when we see the natives of particularly warm countries enveloped in woolen, as the Arab in his burnoose, or the Spanish peasant in his tobacco-colored cloak. Such materials protect both against the rays of the sun and against the coolness of the night, and are excellent regulators of heat. It is dangerously imprudent to travel in southern countries without provision of warm clothing.

The hat completes the dress, as the roof crowns the house. It preserves the head from insolation and cold, and protects it against accidents. Without going so far as M. Bouchardat, who says that the best head-dress is none, we content ourselves with remarking that the hat should be light and well aired. According to M. Troupeau's experiments, conical and rounded head-coverings are cooler than flat ones, and preferable in hot countries.

The bed is not only a piece of furniture indispensable to secure repose; it is also, in fact, a dress for the night. Like other articles of clothing, it should be both warm and permeable to the air. The heat which the body gives off to the mattress and the coverings is continually taken away by the air that traverses them. "Beds designed to regulate the flow of heat," says Dr. Pettenkofer, "are with us thicker than the garments which clothe us during the day, for two reasons: first, because, the circulation being less active during rest and sleep, less heat is evolved; and, secondly, because the ascending currents cool us more rapidly in the horizontal than in the vertical position, where they rise from the feet to the head, passing over the whole body." The heat of the bed thus favors the peripheric circulation and assists the internal organs that have to keep up the calorification. To do without a bed for several days in succession is a great privation, not only because it deprives the limbs of rest, but also because of the troubles to the economy it induces. A too hot and too soft bed is also objectionable because it keeps the body in a condition of moisture that enfeebles the muscular system and reduces all the functions. Feather-beds are generally more noxious than useful. They are warm on account of the air they hold; but an air-mattress should be as warm. Birds also clothe themselves in heat when they sleep, by ruf-