Of course, while digestion and muscular activity are at their height, the body temperature is highest. The temperature, as a rule, decreases from about six at night until four or five in the morning, when it is usually at its ebb. This is a point of importance. A degree or two of increase in temperature, above normal, if recorded about six at night, is not, in most conditions, considered alarming by the physician. Anything which causes an increase in heat radiation, as perspiration, lowers the temperature, and the open pores of the skin are valuable aids in equalizing the body heat. A person who perspires freely does not suffer with heat during excessive exercise, as does one whose pores are closed. Diuretic foods and beverages, such as water and fruits (melons, lemons, oranges, grapefruit, etc.), which increase the activity of the skin and the kidneys, also tend to lower the body temperature. One ready means of regulating the body heat is the _bath_. If one takes a hot bath, the temperature is materially raised by the artificial heat, but there is a recompense in the increase of heat radiation from the skin and the reaction is cooling. If one takes a cold bath, the immediate effect is cooling, but the activity set up within, to create a reaction, soon heats the body to a greater degree than before the bath. The best way to increase the evaporation and thus decrease the temperature of the body is by a tepid shower or a tepid sponge. The tepid water will not create a strong reaction, and it will cause a decrease in temperature. Thus, for fever patients or on a warm day, the tepid shower or sponge is commended; for a cold day, or for the individual whose circulation is sluggish, the cold bath, followed by friction, is desirable. When the vitality is low, so that reaction is slow or chilly feelings persist, the bath must be tempered and greater friction used. The generation of heat is also increased by solid foods that require more than normal activity on the part of the digestive organs. For this reason the food given fever patients should be that most easily digested and should be reduced in quantity. Liquid or semiliquid foods are best. While the elements of the food are being oxidized, the latent (potential) energy released by the oxygen creates mental and physical force and keeps active the metabolic changing of food into tissues and cells, also the changing of cells and tissues into waste. Scientists have measured the energy latent in food material, also the amount of heat given off in the oxidation of a given quantity of waste. The unit of measurement is the _calorie_—the amount of heat which will raise one pound of water 4 degrees Fahrenheit. The fuel value of any food denotes the total number of calories which may be derived from a pound of that food if it be completely oxidized in the body. C. F. Langworthy gives the fuel value of proteins, fats, and carbohydrates as follows: