economically to obtain protein in its cheapest form, and to use no more than is sufficient for the requisite nitrogen and then to use carbohydrates (starches, etc.) in preference to fats for carbon and hydrogen. Oatmeal, beans, potatoes, and wheat flour are among the cheapest foods, considering their nutritive value, as oysters, salmon, and lobsters are among the costliest. See Food.
Exercise. The most important effect of muscular exercise is produced on the lungs, the quantities of inspired air and of exhaled carbonic acid being very much increased. Taking the air inspired in a given time in the horizontal position as unity, a man walking 3 miles per hour inspires 3.22; and if carrying 34 pounds, 3.5; a man walking 4 miles per hour inspires 5; and when walking 6 miles per hour no less than 7. Almost twice as much carbonic acid is exhaled during exercise as during rest. Hence, muscular exercise is necessary for the due removal of the carbon. The effect of exercise on the mind is not clearly determined; great bodily activity is often observed in association with full mental activity; and better intellectual work can be done by one who exercises physically daily. Digestion is improved by exercise. The appetite increases, and nitrogenous substances, fats, and salts, especially phosphates and chlorides, are required in greater quantity than in a state of rest. The change of tissues is increased by exercise, or, in other words, the excretions give off increased quantities of carbon, nitrogen, water, and salts. The muscles require much rest for their reparation after exercise, and they then absorb and retain water, which seems to enter into their composition. So completely is the water retained in the muscles that the urine is not increased for some hours. The old rule, held by trainers, of only allowing the smallest possible quantity of fluid, is wrong. See Exercise; Gymnastics; Physical Training.
Clothing. The object of clothing is to preserve the proper heat of the body by protecting it from both cold and heat, and thus to prevent the injurious action of sudden changes of temperature upon the skin. The most important materials of clothing are cotton, linen, wool, silk, leather, and india-rubber. Cotton, as a material of dress, wears well, does not rapidly absorb water, and conducts heat much less rapidly than linen, but much more rapidly than wool. From the hardness of its fibres, its surface is slightly rough, and occasionally irritates a very delicate skin. Its main advantages are cheapness and durability. In merino it is mixed with wool in various proportions, and this admixture is far preferable to unmixed cotton. Linen is finer in its fibres than cotton, and hence is smoother. It possesses high conducting and bad radiating powers, so that it feels cold to the skin; moreover, it attracts moisture much more than cotton. For these reasons, cottons and thin woolens are much preferred to linen garments in warm climates. Silk forms an excellent underclothing, but, from its expense, it can never come into general use. Wool is superior both to cotton and linen in being a bad conductor of heat, and a great absorber of water, which penetrates into the fibres and distends them (hydroscopic water), and also lies between them (water of interposition). During perspiration, the evaporation from the surface of the body is necessary to reduce the heat which is generated by exercise. When the exercise is concluded, evaporation goes on, and to such an extent as to chill the body. When dry woolen clothing is put on after exertion, the vapor from the surface of the body is condensed on the wool, and gives out again the large amount of heat which had become latent when the water was vaporized. Therefore, a woolen covering, from this cause alone, at once feels warm when used during sweating. In the ease of cotton and linen, the perspiration passes through them, and evaporates from the external surface without condensation; the loss of heat then continues. These facts make it plain why dry woolen clothes are so useful after exertion. In addition to this, the texture of the wool is warmer, from its bad conducting power, and it is less easily penetrated by cold wind. India-rubber clothing must be used with caution. From its being impervious to air, and from its condensing and retaining perspiration, it is decidedly objectionable; while, on the other hand, its protection against rain is a very valuable property.
In relation to protection against heat, we have to consider the color and not the texture of clothing. White is the best color, then gray, yellow, pink, blue, and black.
The shape and weight of all articles of clothing should be such as to allow of the freest action of the limbs, and in no way to interfere by pressure with the processes of respiration, circulation, and digestion.
Personal Cleanliness. Attention to the state of the skin is of great importance in a hygienic point of view. The perspiration and sebaceous matters which are naturally poured out upon the surface of the body, with an intermingling of particles of detached epidermis, fragments of fibres from the dress, dirt, etc., if not removed, gradually form a crust which soon materially interferes with the due excreting action of the skin. There is little doubt that the daily use of the cold sponge-bath, which less than half a century ago was unknown, and is now a matter of necessity with most healthy persons who have the means of using it, has contributed materially to the preservation of health and the prevention of catarrhal attacks.
Consult: Robinson, Sewage Disposal (London, 1882); Richardson, The Field of Disease: A Book of Preventive Medicine (ib., 1883); Waring, How to Drain a House (New York, 1885), and The Disposal of Sewage and the Protection of Streams Used as Sources of Water Supply (Philadelphia, 1886); Plunkett, Women, Plumbers, and Doctors (New York, 1885); Wilson, Handbook of Hygiene and Sanitary Science (Philadelphia, 8th ed., 1892); Roechling, Sewer Gas and Its Influence Upon Health (London, 1898); Reid, Practical Sanitation (ib., 1901); Baker, Municipal Engineering and Sanitation (New York, 1902); Sedgwick, Principles of Sanitary Science and the Public Health (ib., 1902); Chapin, Municipal Sanitation in the United States.
SAN JACIN′TO, Battle of. The final battle in the war for Texan independence, fought near San Jacinto Bay, Texas, April 21, 1836, between about 740 Texans, under General Houston, and about 1400 Mexicans, under Santa Anna. On April 20th the opposing forces took up positions about one mile apart, and after some preliminary skirmishing the battle took place on the afternoon of the following day. It was hardly more than a sharp charge by the Texans, who
