354 WOOD TRANSPORT BY WATER. 



hydraulic works, and manual labour is required to conduct 

 the floating. Hence floating has become a highly elaborate 

 undertaking, in the carrying - out of which many costly 

 constructions and protective works are needful. 



1. Conditions necessary for Streams to be Utilizable. 



Independently of artificial improvements which may be 

 effected, a watercourse used for floating timber must possess 

 certain natural peculiarities, depending on the direction, 

 power and fall of the stream. The direction must eventually 

 lead to the timber-markets, however much the stream may 

 wind on the way there. Not unfrequently artificial channels 

 are cut in order to shorten the course of the stream. 



The minimum width admissible is the length of the logs to 

 be floated, as, unless they have room to turn, constant blocks 

 will occur during floating. Only in the case of artificial 

 floating-channels, where the banks are quite smooth, and 

 butts for saw-mills are floated, may the width of the stream 

 be less than the length of the logs. 



The maximum width of a stream used for floating depends 

 on the possibility of securing and extracting all sunken wood 

 by means of ordinary appliances. Even with the best 

 management some of the heaviest logs will sink, and this 

 sunken wood is either carried along the bottom of the stream, 

 or sticks in holes in its undermined banks. In very broad 

 streams sunken wood cannot be guided to the shore or other- 

 wise secured. Hence, unless the logs are being rafted, the 

 breadth of streams used should not exceed that of a large 

 brook, or small river. 



The depth of the water is also an important point; this 

 should be sufficient to float water-logged timber which will not 

 quite sink, without danger of its grounding on the bottom of 

 the stream. Long and slowly running streams should be 

 deeper than rapid streams, which carry the timber better 

 where the distance for floating is short, and there is, there- 

 fore, less chance of the wood becoming water-logged. When 

 large, round timber is floated, a greater depth is necessary 

 than for poles and split wood, which are easier to float. 



