A YEAE IN SCIENCE 71 



Apparatus 



Beaker Glass plate 



Ice Bunsen burner 



Flask 



Directions : A. Fill the beaker with small pieces of 

 ice and water. Dry the surface of the beaker thor- 

 oughly and set it aside, for about five minutes. At 

 the end of that time what do you find on the surface 

 of the beaker ? How do you account for it ? 



B. Fill the flask half full of water and place it over 

 the Bunsen flame. Heat the water until it boils. Hold 

 a dry glass plate over the mouth of the flask. What 

 do you find on the plate? What is its source? Why 

 did you use the glass plate ?. What happens, when the 

 temperature of the atmosphere is suddenly lowered? 



Exercise 44. Study of the Weather Map. 

 Object: To study the causes of weather changes. 



Apparatus 



Several weather maps for each pupil. These maps should 

 include some with well developed low regions and some with 

 well developed high areas. 



Directions: At the lower left corner of the map are 

 "Explanatory notes." Kead them. At the lower right 

 corner of the map is the " Wind-barometer indication. ' r 

 Study this. 



Locate the isothermal and isobaric lines. What does 

 each mean? All barometric readings have been 

 reduced to what they w r ould be if the place were at 

 sea level. 



