54 ANSWERS TO PRACTICAL QUESTIONS 



It will. For the same reason that a thermometer, in the 

 wind, will indicate the same temperature as in the still air, al- 

 though the former seems to us much colder. 



29. Which makes the better holder when one wishes to 

 protect his hands from a hot dish, woolen or cotton ? 



Woolen, because it is so poor a conductor of heat. 



30. Which ivill give out the more heat, a plain stove or 

 one with ornamental designs ? 



The latter, since it has more radiating surface. 



31. Does dew fall? 



No; it forms directly where it is found. The vapor merely 

 collects on the cold surface. 



32. What causes the " sweating " of a pitcher ? 



The vapor of the air condenses on the cold pitcher. It is 

 often a sign of rain, since it shows that the air is full of vapor 

 easily deposited. 



33. Why is evaporation hastened in a vacuum ? 



Because the pressure of the air is removed. 



34. Does stirring the ground around plants aid in the 

 deposition of dew ? 



It does, since it facilitates radiation. 



35. Wliy does the snow at the foot of a tree melt sooner 

 than that in the open field ? 



The tree absorbs the sun's heat, and then radiates it out, 

 thus serving as a carrier for the snow. 



36. WJty is the opening in a chimney made to decrease 

 in size from bottom to top ? 



Because as the heated air rises it cools and shrinks. If 

 the chimney did not diminish in size correspondingly, currents 

 of cold air would set down from the top. 



37. Will tea keep hot longer in a bright or in a dull 

 tea-pot ? 



