Innate Intelligence is able, through the specially devised machinery of the body, to maintain a perfect balance between heat production and heat dissipation or heat loss. Even though the temperature of the air may rise, yet if the body is normal it will not produce an increase in the bodily temperature. Indeed, it is asserted that when the temperature of the air goes above 70° F. the bodily temperature would rise if it were not for the perspiration which Innate will produce through the sweat glands. As long as the perspiration is produced and is evaporated from the surface of the body the heat production and heat loss will be kept in perfect balance. But when something interferes with this adaptative process of Innate and the individual can not perspire, there will soon be symptoms of overheating and the temperature of the body will begin to rise. Evaporation is decreased in an atmosphere in which the humidity is high. The reason for this is obvious; the atmosphere already filled with water vapor is slow to take up more. This is because molecules of vapor given off from the body collide with those in the air and are returned to the surface of the body as moisture. When this condition obtains there is an adaptation produced by increasing the amount of blood to the skin; this increases the temperature of the surface of the body, but allows for an increase in the heat loss by radiation, conduction and convection. The conductivity of the atmosphere for heat is increased by an increase in the humidity; hence a cool damp air will chill the body for the reason that the conductivity is increased and bodily heat is lost more rapidly through conduction. Increased humidity interferes with the evaporation of perspiration; hence a hot, moist air is heating to the body and deprives the body of force, making the patient feel sluggish and fatigued. There is much moisture given off from the body each day. It is estimated by Pettenkofer, Voit, Rosenau and others that the average individual under ordinary circumstances will give off through the lungs about 290 grams, and from the skin from 500 to 1800 grams daily. If this fact is kept in mind some idea of the necessity of proper ventilation will be appreciated. Warm Moist Air Workers fatigue much more easily when in warm moist atmosphere. Work is done much more rapidly in cool dry air and the efficiency of the worker is noticeably raised; in warm damp air the bodily temperature rises and the pulse rate increases. Mental and physical activities are reduced in an atmosphere of high humidity and increased temperature. This is due mainly to the reluctance on the part of the individual to put forth an effort sufficient to perform any great amount of work. There is a general feeling of languor because of the enervating effect of the air.