100 LAKES. 



precipitate the water sooner into the rivers ; and thus 

 the rain passes off in an overwhelming flood. By the 

 interposition of lakes, this is prevented. They act as 

 regulating dams ; the discharging river cannot rise 

 higher than the lake ; and thus, when the lake is large, 

 a flood which otherwise would flow off in a day, and 

 destroy as it flowed, is made to discharge itself peace- 

 ably for \veeks. Besides the preventing of devastation, 

 this is of advantage to the country. When the flood 

 passes off, while the rain is falling, and the air is moist 

 and not in a state for evaporation, the land derives but a 

 small and temporary advantage from the rain ; but when 

 the water is confined till the state of the atmosphere 

 changes, a considerable portion of it is taken up by 

 the process of evaporation, and descends in fertilizing 

 showers. 



A decisive proof of the advantage of lakes, and the 

 casualties that result from the want of lakes to regulate 

 the discharge of mountain rivers, was unfortunately 

 given in the floods in Scotland, in the summer of 1829. 

 The whole of the rivers that flow eastward from the 

 Grampians have steep courses, but no lakes to regulate 

 their flow ; and the consequence was, that they threw 

 down the bridges, flooded the fields, washed away the 

 soil and crops, and did other damage ; while those 

 streams farther to the north, that roll an equal or a 

 greater mass of water, but which are expanded into 

 lakes, did no harm. Mountainous countries, in which 

 there are no lakes, are usually barren, or in the pro- 

 gress of becoming so. The Andes in America, the 

 ridges in Southern Africa, and many other lakeless 

 elevations, are utterly sterile. The mountains of Scot- 



