Many people have lived for more than a month without food. You can go for days without water. But if you are deprived of air for but a few minutes, your death is certain. Sixteen to eighteen times a minute the normal person respires, one breath being taken for every four beats of the heart, the central engine of life. Each time you breathe, the amount of air which passes into the lungs is about twenty-five cubic inches; which represent, however, but a small part of the actual capacity of the lungs. The average man can take into the lungs with an ordinary inspiration one hundred or more cubic inches, and is able to force out an equal amount with an ordinary expiration. If you have striven your utmost to expel all the air possible from your lungs, there will still remain about one hundred cubic inches of air within them. The total lung capacity of the average man is about three hundred and twenty-five cubic inches, or nearly one and a half gallons of air. THE INDISPENSABILITY OF OXYGEN Sunlight is the basis of all life. It is sunlight which plants absorb, and which they transform into materials which go to make up the living tissues of all things. The place of breathing in the process of life is manifold. But its primary function is to make available for the body’s uses the sunlight, or energy, which is stored up in the food we eat. It does this by means of the oxygen which it contains, and the purpose of breathing is to obtain from the air an adequate supply of oxygen. Oxygen is one of the essential materials required for the support of life. Without oxygen the whole life process would come to an end. From every breath that is taken into the body, about one and a quarter cubic inches of oxygen must be obtained by the body, to keep up the fire of life within us. You cannot burn a match, or your reading lamp in the evening, unless there is an adequate supply of oxygen; and even so does the body require this indispensable and all powerful element in order to maintain itself. [Illustration: FRESH AIR IN BERMUDA]