HEAT IN RELATION TO THE HUMAN BODY 25 



unduly laden with moisture, with carbon dioxide, and with organic 

 matter thrown off from the body in the breath. A continuous renewal 

 of the air in closed living rooms, offices, and assembly halls is necessary. 



The problem of ventilation becomes a serious one only during 

 weather when rooms are kept tightly closed on account of the cold. 

 All unnecessary outlays for heating buildings must be avoided, and 

 all drafts of cold air. 



Particular attention should be given to securing an abundance of 

 pure air during the hours of sleep. It is a relatively easy matter to 

 provide sufficient bedding to protect against any danger of being chilled 

 while asleep in a room open to out-of-doors air even in the coldest 

 weather. 



More serious than the dullness of mind and the weariness of body 

 due to oxygen starvation when sleeping in poorly ventilated rooms is 

 the lack of bodily vigor, and the lessened powers of resistance to germ 

 diseases. This menace to health is the greater because the relation- 

 ship is not always apparent, and because the ill consequences are often 

 long delayed. 



The development of tuberculosis in a person could often have been 

 prevented by the same care that is exercised later in an effort to effect 

 a cure through being much out-of-doors, and by having suitable em- 

 ployment, sufficient exercise, and nourishing food. 



In the rhythmic rise and fall of the diaphragm nature has provided an 

 important means of continuously stimulating muscular action in the 

 digestive tract, and of preventing constipation. 



Lung capacity varies much in different persons, and as a rule is con- 

 siderably more in a man than in a woman. It is disuse of the lung 

 capacity, however, that is the really serious consideration. Laziness 

 in breathing should be overcome, but forced and intermittent efforts 

 to do this accomplish but little. There should be enough of active 

 daily exercise to cause a demand by the body for an increased supply 

 of oxygen, thus necessitating deeper breathing. 



The chances for life at times of choking or of drowning may depend 

 upon the reserve air in the lungs. Everyone should know just how to 

 proceed to resuscitate a drowned person. 



THE HUMAN BODY AS AN ENGINE, AND THE REGU- 

 LATION OF BODY TEMPERATURE 



The fact that a person can do work and can move about 

 presupposes the existence of energy by use of which these 



