132, LITBEATURB ON TOBRBNTS. 



fin3,lly in, the Em^t-August-StoUen— situ3,ted at. about 370 mfetres (1260 

 feet) under the plateau, of Chausthal. This canal, in wMch are collected 

 all the waters of the subterranean sheets, conveys them to the open air at 

 Gittelde ; it is not less than 23-60() metres in length, and its other dimen- 

 sions are considerable, fpr thig long subterranean passage can be made by 

 boat. Its breadth is 1-90 mfetre (6 feet 4 inches), and its height 2-70 (or 9 

 feet). This magnificent work was completed in 1864, and cost a little more 

 than three millions of francs." 



M. Cezanne goes on to say, — " Many of these works date from the begin- 

 ning of the eighteenth century. It is a hundred and fifty years since the 

 inhabitants of the German Hartz have subdued, tamed, and turned to use 

 their running waters ; it is only ten years since we began to give ourselves 

 to the, attacking and mastering of the torrents of the Alps ! " 



In the German literature of Forst-Kunde are not a few treatises on 

 torrents, on their destructive effects, and on the means of preventing and 

 counteracting these. 



StrefSeur refers to a brochure by Franz Duile. It was published in 1826, 

 under the title Ueher YerbaunuTW) der WildhacM in Gehirgs Landern, and 

 in it the atuthor gives an exposition of the principles which should be 

 applied to all works of this kind. 



"He studied successively," says Marschand, "the construction of stone 

 dams and of wooden erections having the same object to accomplish. The 

 former, described by him, are dry-stone dykes, and are composed of a 

 horizontal vault with the arch directed up the stream, and sustaining walls 

 forming kinds of butments where the hiUs are not of rock, and to prevent 

 underminings a radier or screen of stone retained by wood-work. The 

 summit of the dam is lowered somewhat in the middle to facilitate the flow 

 of I water, and it is covered with a wooden plank designed to maintain the 

 solidity of the summit. The wooden barrages described by him are similar 

 to Ahose in use in many parts of the French Alps. 



" Duile superintended numerous works on torrents, but through neglect, 

 oripeiihaps through the force of the current, they all crumbled into ruins ; 

 and. at the close of his life he expressed to Professor Culmann regret that 

 he had undertaken works against torrents. 



" He treated also of rehoisement, assisted by clayonnages or hurdles, and, 

 in a word, of everything relating to the extinction of torrents. 



" Great works undertaken by his advice leave no doubt of the efficacy 

 of his system." 



In 1844 was published at Darmstadt Das Verdrangen der Lauh-Wdlder, 

 in Nordlichen I)eutscMande divrch die Fichte und der Eeifer, by Edmond 

 von Berg. In 1852 was published at Erlangen Das Verhalten der Wald- 

 hawme gegen Licht und Schatten, by Gustav Heyer ; both of which have 

 reference to the subject under consideration. 



In a Sandbuch der Physischer Geographie by Klbden, referred to by Marsh, 

 it is stated by the latter that the author, " admitting that the rivers Oder 

 and Elbe have diminished in quantity of water — the former since 1778, the 

 latter sinpe 1828 — denies that the diminution of volume is to be ascribed 

 to a decrease of precipitation in consequence of the felling of the forests ; 

 and states, what other physicists confirm, that during the same period 

 meteorolpgical records, in various parts of Europe, show rather an augment- 

 atipu than a reduction of rain." 



