o- 





MAN'S USE OF COMPRESSED AIR 



the lowest level of the caisson is frequently thirty 

 pounds per square inch and sometimes may have to 

 be increased to forty-five or fifty pounds. 



U MEN AT WORK IN A CAISSON 



Men who must work in caissons sometimes suffer 

 from a peculiar ailment called "caisson disease" or 

 "the bends." This used to cause many deaths among 

 the workers until it was found that it was caused by 

 changing too quickly from the greater pressure in the 

 caisson to atmospheric pressure. Modern safeguards 

 provide a gradual change from one pressure to an- 

 other. A study of Figure 30 will show you how this is 

 accomplished. 



REFERENCES FOR FURTHER STUDY 

 Texts 



Caldwell and Curtis, Science for Today, pp. 47-53 

 Clement, Collister, and Thurston, Our Surroundings, pp. 41- 

 42 



- / 



Hunter and Whitman, Science in Our World of Progress, 



pp. 53-57 

 Lake, Harley, and Welton, Exploring the World of Science, 



pp. 32-37 

 Pieper and Beauchamp, Everyday Problems in Science, pp. 



485-489 



Powers, Neuner, and Bruner, The World Around Us, Chap. 8 

 Van Buskirk and Smith, The Science of Everyday Life, pp. 



30-31 



Watkins and Bedell, General Science for Today, pp. 11-19 

 Wood and Carpenter, Our Environment: How We Use and 



Control It, pp. 118-122 



Special References 



Corbin, Romance of Submarine Engineering 

 Darrow, Masters of Science and Invention 

 Fraser, The Story of Engineering in America 

 Bond, With the Men Who Do Things 



WHAT YOU SHOULD AIM TO ACQUIRE FROM 

 THIS STUDY 



1. A knowledge of the construction and operation of 

 the caisson in the building of bridges, tunnels, and 

 dams. 



2. A knowledge of the uses made of compressed air in 

 drills, sprays, sand blasts, and other devices. 



TEST OF MASTERY OF THE TOPIC 



In your notebook answer the following questions and 

 comply with the instructions. 



1. What pressure is usually maintained in the balloon 

 type automobile tires? 



2. What is the device which measures this pressure called ? 



3. Explain the principle of the caisson. 



4. Make a section drawing of some devices which you 

 have studied that makes use of compressed air, such as a 

 drill, hammer, or perfume spray. 



5. What did George Westinghouse do of importance in 

 connection with this study? 



6. What causes the disease known as "the bends" ? 



7. Write a short account of some undertaking of which 

 you have read where compressed air played an important 

 part. 



8. Make a sectional drawing showing how a caisson is 

 used. 



9. Which of the following experiences have you had? 

 In which of the experiences in the list may you find use 

 for the knowledge gained in this study? 



The use of air brakes on a bus, trolley, or train 



The use of compressed air in lifts 



The use of compressed air in painting 



The use of compressed air in automobile tires 



The use of compressed air in spraying the nose or 



throat 

 The use of compressed air in building a bridge or 



tunnel 



The use of compressed air in operating a drill 

 The use of compressed air in operating a riveting 



hammer 



10. On the basis of the facts learned in this topic, infer 

 what causes the hissing sound as the engineer of a train 

 applies the air brakes. 



