234 FORESTRY IN SWITZERLAND. 



4 



How these constructions are to be managed, continues the author, has 

 been fully explained in previous publications. The replanting of cleared 

 slopes and the banks of streams will be treated of further on in this essay. 

 In order to spare the trouble of research on the former point the following 

 facts are recalled in regard to the artificial construction of brooks running 

 over uncertain beds as having a tendency to carry off deposits of earth after 

 heavy storms. The damage which even the most insignificant rivulet can 

 cause when swollen to the bed over which it runs ; when the latter is made of 

 bad, z. e. loose and spongy earth, consists in eating it away, a damage the 

 extent of which is, of course, proportioned to the fall of the water. This 

 can be best and most cheaply counteracted by so-called "overfalls" (cross- 

 beams), which sufficiently diminishes the fall of the stream ; only it must be 

 seen to that the requisite number of these are constructed at proper points 

 and in durable form. Without going deeply into the subject of construction 

 theories, unintelligible to the general reader, the author contents himself 

 with stating merely the following practical rules, viz. : 



The simple inspection of a water-course will determine whether it needs 

 any artificial constructions or not. 



Such will, of course, only be needed at points where the bed of the 

 stream is badly washed out, or eaten away. 



Inasmuch as at all points where the mere dropping in of a stone or putting 

 down of fascines does not afford adequate protection the flow of water must 

 be checked ; that is to say, its fall must be lessened, and consequently its 

 level heightened. It will be necessary in such case to construct an " overfall " 

 at some proper point lower down. This should be repeated at every point 

 not immediately secured against farther washouts. 



But an artificial fall, inasmuch as it augments the danger of the washing 

 away of the earth immediately under it, must, all the more for this reason, 

 be located at a point where the earth is firm, and in case such a point cannot 

 be found below the washout then some such course as the following should 

 be adopted : Lay a solid plank or several cross pieces across the brook so 

 that they are sufficiently imbedded in the bank and background, and rein- 

 force the sideis of the stream both above and below with pieces laid length- 

 wise so that the water can find absolutely no outlet at the sides j but be 

 careful at the point upon which the falling water strikes to either place a very 

 heavy stone or to shield it with wood or green osier work in such a manner 

 that the stream cannot undermine it or the earth around it. 



Detailed instructions as to the driving of stakes and putting together of 

 materials at the different points must be left to the practical common sense of 

 the owner immediately concerned or of the expert who may be called in for 

 the occasion. It is, however, recommended, with a view to the permanent 

 safety of the shores adjacent to and on both sides of the "overfall," that 

 they be planted either in the fall or spring with suitable poplars or willows. 



" Where a brook has cut so deeply into its banks that they are in danger of caving in, tlie 

 preservation of these latter must be looked afler. In the simpler cases, this is effected by 

 placing osier works in position, and this is to be done in the fall or at latest in the spring, the 



