506 NATURE STUDY. 



Who's the master that you serve, 



Bids you lift your tiny sails, 

 Brings you safely to the earth, 



Guides you through the wintry gales ? 

 He who tells the birds to sing, 



He who sends the April flowers, 

 He who ripens all the fruit, 



That great Master, He is ours." 



E. A. RAND. 



WATER DUST, DEW, RAIN. 



Water dust. Begin again with experiments showing 

 formation of vapor and water dust. Show how this is 

 condensed into drops, impressing the importance of cold 

 by showing how much more rapidly the drops of water 

 are formed when a cold slate or glass or plate is used than 

 when a warm object is placed in the vapor or water dust. 

 Dew and rain are thus readily formed in the schoolroom. 



A jar or pitcher of ice- water in the room may show the 

 condensation of water on its surface. If the air of the 

 schoolroom is too dry, place a bottle of ice-water on a 

 cork or block in a saucer containing a little warm water, 

 and invert over the bottle a glass jar. Heating this 

 slightly over the alcohol stove will cause a more rapid 

 evaporation of the water in the saucer, and insure the con- 

 densation of dew on the surface of the cold bottle. To 

 form water dust we find necessary water, some heat to 

 cause evaporation, some cold to cause condensation. 



Dew. Apply these conditions to explanations of dew. 

 It forms in low, damp places, or near the sea or lakes or 

 rivers when there may be no dew on the hills or away 

 from water. Why ? It forms in the evening, not usu- 

 ally in the daytime. Why ? Dew is most apt to form 

 when there is little or no wind. Why ? It is a little more 

 apt to form on clear nights than on cloudy nights. Why ? 



Touch on the uses of dew. Many regions depend largely 



