FLOATING. 



383 



to 5f feet broad, and 1} feet deep; it brings-down very large 

 butts for tbe saw-mills. It is there constructed of blocks of 

 granite, lower down its banks are made of wood, but in 1882 

 the floods proved too much for these wooden constructions. 

 In the lowest section, where there is much more water available, 

 the width of the canal is 10 feet. 



In constructing such canals the chief point is to secure a 

 good supply of water, and owing to the snowfall in mountainous 

 regions this can generally be done. The line is then taken, as 

 far as possible, through all adjoining mountain-streams, or it is 

 supplied with water by reservoirs and dams. 



iv. Lateral Booms. 



All streams used for floating have branches either natural or 

 artificial, and arrangements must be made to keep the wood out 

 of such bifurcations, or in certain cases, to conduct it into a side 

 stream. To efi"ect this, lateral booms either floating, or fixed in 



Fig. 224. 



the bed of the stream, are required. A thoroughly dried spruce- 

 log fastened to the bank of the stream by withes and floating in 

 the water in front of the side-stream vdll often suffice. 



Should the width of the stream be so great that this is not 

 sufficient, a ch:iiu of two or more logs (fig. 224) attached 

 together either by withes or iron rings, may be substituted. 

 These are floating booms. Wherever a boom has to withstand a 



