12 NATURE'S STORY OF THE YEAR 



What is the purpose of this ceaseless babbling 

 stream ? The dip whence it comes proves that 

 though it trickles clear it bleeds the heart of its 

 parent. By boiling the water we discover its 

 unseen burden, to the extent of some twenty-two 

 grains of soluble matter per gallon. If we credit 

 the streams with the removal of a third of the rain- 

 fall (a moderate estimate) they would give the 

 figure of two hundred tons of dissolved materials 

 per square mile, removed by them every year. To 

 this calculation must be added the amount of the 

 organic matter carried by the water ; and we then 

 have an indication how valleys have been shaped, 

 if not wholly formed. 



The watery vapours rise pure and empty from 

 the sea. They pass over the land, and the liquid 

 falls 



"To trickle down the hills, and glide again, 

 Having no pause or peace." 



But when it passes in rivers to the sea, it is satu- 

 rated with the burden of dissolved matters. Thus 

 the sea, for ever pouring upon the land a vapoury 

 tide, and for ever receiving from it an enormous 



