THE TORRENTS OF SWITZERLAND. 



47 



Grisons, were visited by floods of enormous magnitude. Such, was the 

 devastation caused that an appeal was made to the generosity of the 

 nation at large in behalf of the sufferers. This was responded to 

 with such liberality that a large portion of the sum subscribed was 

 put aside for the purpose of improving the water courses perma- 

 nently. The fact that collective action was necessary in the attempts 

 to control the turbulent streams became very apparent. This being 

 the case, the state was called upon to take charge of this colossal en- 

 terprise. In July, 1871, by federal decree, the confederation de- 

 clared that the correction and extinction of torrents was a matter of 

 public utility, and worthy of the subsidies of the national Govern- 

 ment. At the same time the relative burdens of the cantons and the 

 confederation were settled. The importance of the improvement of 

 the water courses and of the wooding of the regions where they rise 

 was recognized in the Constitution of 1874. There the matter was 

 definitely put under federal control and classed with the allied ques- 

 tion of theVonservation of the forests. The problem of keeping the 

 waters under control in Switzerland ranges from the marshy low- 

 lands to the summits of the passes. In spite of the varying condi- 

 tions that this range entails, there are certain general principles that 

 bear on all cases where the water is in movement. As the Swiss sup- 

 plies his want of coal by harnessing his streams, so he makes the 

 water do a large share of the work of correcting its erring ways 

 and preparing itself to be harnessed. This he does by utilizing its 

 power of carrying or depositing stones and soil, according as it is held 

 within narrow banks or allowed to roam at will. As this power de- 

 pends also on the steepness of the slope down which it runs, he uses 

 this latter factor as well. 



When he has got the water courses into what he considers 

 good working condition and one that should be permanent, he tries 

 to clinch matters. This is done \j so combining the various condi- 

 tions of cross-section, slope, and quality of soil that the action of 

 the water is automatic — that is, it brings down no more earth and 

 stones than it is capable of carrying below to safer places where the 

 dangers of floods are small. Whenever the force with which the 

 water moves along is stronger than the cohesion of the soil, erosion 

 occurs. This erosion will continue, the channel of the stream be- 

 coming ever deeper, until a soil is encountered whose resistance is 

 equal to the erosive action of the water. As the alluvion is carried 

 on, the slope of the stream will become steeper and steeper the higher 

 one goes. This circumstance would be of much greater importance 

 if the gorges and gullies in which most of the streams run were not 

 so well provided with rock. The power of the water to cause erosion 

 is lessened in proportion to the amount of material it is carrying with 



