MEASURING ATMOSPHERIC PRESSTJEE 45 



9. Why will a swinging door open slightly if some one opens a 

 door quickly in another part of the room? 



10. Why is it difficult to drink from a small-mouthed bottle? 



11. What makes soda water rise in a straw? 



12. Why would it be impossible to suck up soda water through a 

 piece of glass tubing extending through a perforated rubber stopper, 

 if the stopper closed the bottle tightly? 



13. What is meant by suction shoes? 



14. How does the boa-constrictor use atmospheric pressure to 

 swallow its food? 



15. Why does it tire one to walk in the mud? 



16. Why is it necessary to use on a vacuum cleaner one kind of 

 an attachment for cleaning hardwood floors, and a different kind 

 of an attachment for carpets? 



17. About what is the weight of the air in your room? 



18. Why will not the cover of a preserving jar stay on securely 

 if the cover is put on when the can is cold? 



19. Why will two glasses stick together if one is placed within 

 the other immediately after washing them with hot water? 



20. If two books are placed on the table about 2 inches apart, 

 and a sheet of paper placed over them, explain why the paper sinks 

 between the books when one blows between them. 



21. Why does the liquid from an atomizer rise in the tube when 

 air is forced over the mouth of the tube by pressure upon the rubber 

 bulb? 



MEASURING ATMOSPHERIC PRESSURE 



The Barometer. The barometer, which only recently has come 

 into popularity, was " invented " nearly three hundred years ago. 



The work in connection with this invention is very interesting. 

 It seems that Galileo Galilei, an Italian philosopher and mathe- 

 matician (Born 1564 Died 1642), was asked, toward the end of his 

 life, to explain why water could not be raised in a suction pump to 

 a greater height than 32 feet. 



He was led to believe that the pressure of the air did not exceed 

 the pressure of a column of water 32 feet high; but subsequently he 

 devised an experiment to ascertain the pressure of the air. 



