292 INFLUENCE OF WOODLANDS UPON STREAMS. 



jM. Coute-Grandchamps, engineer of roads and bridges, in an official 

 report of engineering operations for irrigation, which included the ques- 

 tion of supply as well as delivery in the department of the Basses Alpes, 

 at an elevation of 1,200 to 2,200 meters above sea-level, has made this 

 subject of the influence of forest a subject of long and careful study, 

 and with these results : 



In granitic soils, at 1,000 meters above the sea, the delivery of water 

 by springs is twice as great in wooded regions as in those that have 

 been deforested; and that rewooding, joined with works for storage, 

 may augment by 7 cubic meters daily per hectare rewooded the deliv- 

 ery of springs. Some springs that have failed from deforesting, have 

 reappeared with forest vegetation. He had oftentimes observed in the 

 mountains, that fogs caused true rain in forests of fir, while they left no 

 traces of humidity on the denuded lands. 



Mr. E. U. Piper, in his Trees of America (Boston, 1855), mentions an 

 illustration of the return of water by restoring the woodland shade, as 

 coming under his own observation : 



"Within about one-half mile of my residence there is a pond npon -which mills have 

 been standincj for a long time, dating back, I believe, to the tirst settlement of the 

 town. These have been kept in constant operation until within about 20 or 30 years, 

 •when the supply of water began to fail. The pond owes its existence to a stream 

 which has its source in the hills which stretch some miles to the south. Within the 

 time mentioned these hills, which were clothed with a dense forest, have been almost 

 entirely stripped of trees ; and to the wonder and loss of the mill-owners, the water in 

 the iiond has failed, except in the season of freshets, and, what was never heard of be- 

 fore, the stream itself has been entirely dry. Within the last 10 years a new growth 

 of wood has sprung up on most of the land formerly occupied by the old forest, and 

 now the water runs through the year, notwithstanding the droughts of the last few 

 years. 



Professor Newberry, in his Geology of Ohio (i, 24), mentions a fact 

 which seems to indicate that the Ohio River was extremely low at a 

 period remotely passed, but still within the reach of human history. It 

 is well known that from the drying up of tributaries, the Ohio has been 

 getting lower and lower in dry seasons for many years. About 1871-'72 

 the waters sank lower than had been known before, and at Smith's Ferry, 

 where the Pennsylvania line crosses, a ledge of rocks was laid bare that 

 had not been seen before by the present inhabitants. On this surface, 

 from 50 to 100 feet and several hundred yards long, inscriptions have 

 been made, such as are ascribed to a race which densely populated the 

 country before the advent of the recent Indian tribes. It is possible to 

 conjecture that the clearing of forests by an agricultural race may have 

 brought about the conditions now existing, a long interval of neglected 

 culture and forest growth having since intervened. 



The effects of forest-waste upon rivers were very fully discussed at 

 the International Congress of Land and Forest Culturists, in their ses- 

 sion at Vienna, in September, 1873, and startling facts bearing on the 

 subject were presented. Instances were cited showing that, in conse- 

 quence of clearings, there has been a gradual decrease in the depth of 

 the large streams of all countries. In some cases rivers, which in former 

 times had been of considerable magnitude, Iiad entirely disappeared. 

 The Rhine, the Elbe, and the Oder are all shallower now than in the 

 past. It was asserted that the depth of the Elbe at Altenbriicke, in 

 Hanover, in 1787, was 48 feet at low water. In 1812 it had decreased 

 to 4G feet inches ; and in 1837 a further reduction to 38 feet was indi- 

 cated, making a diminution of 10 feet in half a century. The Elbe rises 

 in Bohemia, where, until recently, the forests were under no control, and 

 so were destroyed in the most random manner. The Rhine, also, has 



