122 QUESTIONS ON THE 



242. Why will not the siphon act, when the longer leg 

 is immersed in the liquor that is to be drawn off? 



243. On what principle are Fire Engines ? 



244. If a body weigh 74 grains in air, and 68 in 

 water, what will be its specific gravity ? 



<2'J5. If a body weigh 136 grains in air, and 120 in 

 water, what will be its specific gravity ? 



*245. If a tube of one inch bore, and 30 feet high, be 

 inserted into a cask of water, whose base is one foot in 

 diameter, what will be the pressure if the tube be filled 

 with water ? 



246. If it were possible that the quicksilver could 

 rise in a barometer to 40 inches, of what height would 

 be the column of water that might be counterbalanced 

 by it in a pump ? 



ACOUSTICS. 



247 . Of what does Acoustics treat ? 



248. Is air the sole transmitter of sound ? 



249. Define Sound. 



250. On what does the intensity of sound depend ? 



251. What difference is there in the intensity of sound, 

 conveyed by hydrogen gas, and by carbonic acid gas ? 



252. What is the name of that nerve which conveys 

 sound to the brain ? 



253. Is the ear the only means by which sound may 

 be conveyed to the brain ? 



254. iVhat effect has the state of the atmosphere in 

 regard to sound ? 



255. Required the number of vibrations in a second, 

 to produce the most acute and the most grave sound ? 



256. Which travels quickest, the human voice, or the. 

 report of a cannon? 



257- At what rate per second does sound travel ? 



258. How may the distance of a thunder-storm be cal- 

 culated r 



259. Give an example of the conducting power of 

 water ? 



