378 



WATER-TRAXSPOIIT, 



weir may be removed iu case of very high water, or to allow 

 timber to pass. 



It has been already remarked that certain works may be 

 necessary to keep silt, gravel or boulders out of reservoirs ; 

 these works are merely weirs made of wattle- work or stone, 



Fig. 219. 



across the small brooks which feed the reservoir, and thus the 

 results of denudation of the hill-sides are kept from descending 

 the water-course. In addition to these weirs, the ordinary 

 measures should be adopted for fixing the slopes on either 

 side of a mountain-torrent, and keeping it stocked with forest 

 irrowth. 



(b) Works for regulating the course of a natural Stream. 

 There is not a single watercourse which is naturally so suit- 

 able for floating timber but that it may be improved by some 

 artificial works, to render the floating more regular and to avoid 

 damage. In strong or weak waters there are always a number 

 of hindrances : the banks may require securing ; it may be 

 necessary to remove obstructions from the bed of the stream by 

 blasting, or otherwise ; sometimes the current requires modify- 

 ing, or bifurcations of the stream should be cut off whilst float- 

 ing is in progress. 



i. Sfn'ii;itJic)iiii;i tlie Banks of Streams. 



Artificial works may be employed with advantage wherever 

 the banks of a stream are too steep, or too sloping, or where 

 the breadth of the stream requires modification. High, steep 



