56 



GENERAL SCIENCE 



6. What is the pressure of the atmosphere in pounds per square 

 inch when the barometer reads 29, 29.5, 30, 30.2? 



7. Why does water stay up in a bottle which is used as a drink- 

 ing fountain for chickens? 



8. Explain the action of a drinking fountain made of an ice chest 

 and an inverted 5-gallon bottle. 



9. Could you siphon water over your school 

 building? 



10. How much force would be required to 

 pull Von Guericke's hemispheres apart? (Air 

 pressure on a circle 22 inches diameter.) 



11. Why do clothes bulge when being pressed 

 into a boiler full of water? 



Problem to look up. 



12. How do the pneumatic tubes work which 

 carry money in department stores and trans- 

 port mail in cities? 



13. What causes the noise when a thimble 

 is suddenly removed 



from a finger? 



14. Why is it neces- 

 sary to have more than 

 one hole in a cocoanut 

 in order to get the 

 milk? 



15. Why does smoke 



FIG. 49. Why does 

 the water stay in 

 the large bottle? 

 Why are bubbles 

 seen rising in the 

 water when a glass 

 of water is drawn? 



FIG. 50a. Magdeburg or 

 Von Guericke's hemi- 

 spheres. 



sink to the ground when the barometer reads low? 

 16. Why does a balloon rise? 



FIG. 506 Otto Von Guericke taught the people of his day something about the 

 pressure of the atmosphere by making two hollow hemispheres which fitted 

 nicely together and removing the air. It is said that all the horses available 

 at the time the experiment was tried were unable to pull the hemispheres 

 apart. 



