1 8 HAND-BOOK OF TREE-PLANTING. 



from the action of the sun and dissolves slowly, 

 remaining to a considerable extent long after 

 the snow has disappeared from the open fields. 

 Thus a protracted and steady flow into the 

 brooks and streams is secured. 



But when the forests along the heads and 

 courses of streams are cut off, the first effect is 

 to dry up the spongy soil, and then to remove it 

 by the combined influence of the sun, wind, and 

 rain. The consequence is, that the water result- 

 ing from rain or the dissolving snow flows down 

 the hill-sides at once, and often causes the 

 streams to become torrents, overflowing their 

 banks and carrying disaster and destruction far 

 and wide. 



For the same reason, when summer comes, 

 with its lessened supply of rain and more rapid 

 evaporation, there is no reservoir upon the hills 

 as formerly to send its steady flow along the 

 water-courses, and so the streams shrink to 

 brooks, and the brooks to mere threads perhaps. 

 The mill-wheels stop, or must be turned by the 

 power of steam. The boats of commerce can 

 not move in their accustomed channels, or are 

 delayed ; and so the many industries of life are 



