HOW DO WE BREATHE? 67 



STORY TEST 



RALPH EXPLAINS How HE USES AIR 



Read carefully and critically. List all the errors and suggest cor- 

 rections. 



I began the day with a sneeze. I used air for that. I did not 

 use air during the night: I never do. I opened the -faucet to get 

 water for washing, the atmospheric pressure made the water run 

 out. I pressed the tube to get tooth paste upon my tooth brush, 

 air pressure made the paste come out. I squeezed the bulb of a 

 sprayer to use an antiseptic for my sore throat, pressure of the air 

 lifted the liquid out of the bottle. Coffee was made for the older 

 folks for breakfast ; in the coffee percolater pressure of the air 

 made the liquid spurt out over the coffee. After breakfast I had 

 target practice with an air rifle and with vacuum-tipped arrows, 

 both of which make use of atmospheric pressure. I tried to fly my 

 kite but the atmospheric pressure was too great and I had to give 

 that up. It was a sunshiny day with absolutely no wind ; the 

 water was calm just the time to have a safe trip in my sail boat. 

 I took a friend across the lake but had to tack coming back. We 

 pumped up an inner tube to take in with us while bathing. We 

 made use of the air in the tube, but atmospheric pressure was not 

 needed as we forced the air into the tube by means of a piston 

 pump. We went home in an automobile. I noticed a fan under 

 the hood and I think it drew air into the cylinders so the gasoline 

 could burn. James and I had a race today. We had gallon jugs 

 just alike, both filled with water. We were to see who could empty 

 the water out first. I tipped mine upside down and held it still. 

 James tipped his as I did but gave it a whirling motion at first to 

 make the water whirl. I won. I started writing this by electric 

 light, but the lights went out and I am finishing by candle light, 

 but the wind blows the flame out every little while. If it were 

 not for the difficulty of lighting, the candles could be sealed in a 

 glass bulb just as the wires of the electric lamp are. They would 

 not blow out so easily then. 



PROBLEM IV. HOW DO WE BREATHE? 



A Day's Air Supply. Did you ever stop to think how 

 much air you take into the body in 24 hours? At the 

 smallest estimate it is over 60 barrels. This seems a lot 

 of air, for most of us could get inside of a single barrel. 



