474 NATURE STUDY. 



dry," one in a compact mass. These experiments will help 

 the children to discover a second answer to the question : 

 What helps slow evaporation or drying ? " Water evapo- 

 rates faster when it is spread out thin." " Things dry best 

 when they are spread out." Apply this to the drying of 

 the slate, and of clothes before the stove or on the line, 

 and of the streets and sidewalks and roofs. 



Show how much more quickly a damp cloth dries, or the 

 ink on the paper dries, when cloth or paper are shaken. 

 Have two or three children slightly wet both hands, and 

 blow on one hand or move one hand rapidly, while the 

 other is held still. Which dries more quickly ? Try to 

 dry two cloths, one where the air is quiet, the other where 

 there is a decided draft or wind. Which dries most rapidly ? 

 Water evaporates fastest, or things dry most quickly, when 

 they are moving or when there is a wind. Apply this to 

 drying of clothes on a line when wind is blowing, and to 

 drying of walks and streets when it is windy. The rela- 

 tion of wind to drying is difficult for little folks, and is of 

 minor importance. We can give them the idea, and let it 

 digest. In a year or two it will mean more to them. It 

 may be illustrated by the carrying of dust by the wind. 



Cannot they understand something of the reasons for the 

 three answers they have discovered to the questions asked 

 them ? Heat helps things to dry, or causes water to evap- 

 orate, more quickly, by breaking it up into very small drops 

 of water dust, and scattering them through the air. The 

 more the water is spread out, and the more shallow it is, 

 the more easily the water dust can get into the air ; the 

 more the water is moved through the air, and the more the 

 air blows over the water, the more it can take up and carry 

 away the drops of water dust. 



Step III. .Blackboard review. An excellent way of re- 

 viewing and impressing the work already done, and at the 



