292 HANDBOOK OF NATURE STUDY 



a flash of lightning appeared to be shot perpendicularly 

 from the clouds; a few seconds later a crash of thunder 

 echoed and reechoed through the forest. Then it began to 

 rain. At first only single drops came through the leafy 

 roofs above us, and it had rained about fifteen minutes before 

 we were getting wet. On our way home, however, we found 

 everything not only wet but thoroughly soaked, and leaves 

 and grasses were loaded with large drops. Do you remem- 

 ber how, an hour later, the boys amused themselves with 

 shaking the rain from the smaller trees ? When we passed 

 through the field, however, the corn, the wheat, and the 

 grass were almost dry, and the roads were no longer muddy. 

 The next forenoon some of the boys went into the woods 

 again after flowers and found the brush still very wet ; but 

 on roads, fields, and prairie the plants and the surface of 

 the soil were perfectly dry, although the rills made by the 

 running water were still plainly visible. Did we see such 

 rills in the woods ? 



From these observations we deduce the following : In the 

 forests the rain reaches the ground and soaks into it quite 

 slowly ; it does not fall upon bare soil; it forms no rills; a 

 considerable part is retained on the foliage of trees and brush, 

 and this part evaporates slowly and thus cools the air. 



Whether the water evaporated .from forests has any ap- 

 preciable effect upon the rainfall of the region is still a 

 question under dispute, but is answered in the affirmative 

 by some good observers. It is, however, an undisputed fact 

 that treeless regions are more frequently visited by severe 

 storms and cyclones and by hot, scorching winds. The 

 great sources of moisture for our Eastern States and for the 

 Mississippi basin are the Atlantic, the Gulf of Mexico, and 

 the Great Lakes. As far as local showers are concerned, it 

 seems to be a fact that they generally follow the wooded 

 valleys and banks of rivers, or hover over lakes ; but the 



