68 



LIVING IN AN OCEAN OF AIR 



It is possible for you to find out roughly the amount of air 

 you use by the following home experiment : Count the 



number of times you 

 breathe per minute. 

 It will likely be some- 

 where from 12 to 16. 

 The average breath is 

 30 cubic inches. Con- 

 sidering your own size, 

 about how many cubic 

 inches of air do you 

 think you take in at 

 a single breath ? Find 

 the amount for one 

 day by multiplying the 

 number of breaths per 

 minute by the volume 

 of each breath and 

 then by the number of 

 minutes in an hour and 

 by 24, the number of 

 hours in a day. A 



barrel holds about 31^ gallons and there are 231 cubic 

 inches in a gallon. You take much more air when you 

 are exercising, since you breathe more rapidly and take 

 deeper breaths. Then, on the other hand, you breathe 

 much slower when you are asleep. 4 You must remember, 

 of course, that your estimate will be only approximately 

 correct because of these differences. 



Why We Breathe. We must think of the human body 

 as any engine. Just as an automobile engine releases 

 energy by burning fuel, so the human body likewise burns 

 or oxidizes fuel to release the energy for daily work. But 

 our work is done not in any one part of the body, but in 

 the little units or cells which go to make it up. Evidently 



Why can this small boy use so many barrels of 

 air? 



