TRANSPORT BY WATER. 



297 



tight troughs, much used in California for rapid transport of 

 logs over long distances in mountain tracts. They have to be 

 carefully laid at a constant low gradient, and have to cross 

 gullies sometimes over 200 ft. deep ; and a speed of 2 to 3 miles 

 per hour is attained with a fall of only 1 in 200, while 1 in 100 

 increases it to from 6-9 miles an hour, and 1 in 20 to over 20 

 miles an hour. On some of the American flumes distances of 

 over 40 miles are covered in less than 4 hours. Such shoots can 

 only be made where a good and constant water-supply is assured. 

 The angle of the V has to be filled with a triangular piece 

 of wood to form a 

 flat base, else logs 

 may get jammed in 

 the trough. 



2. Transport on 

 Inland Waters can 

 take place by loose 

 drifting or floating 

 in rafts. Timber- 

 floating is custom- 

 ary in Strathspey ; 

 but many of our inland waterways might be much more 

 utilised thus, as all of our Conifers and most of our broad- 

 leaved trees are floatable, and water - transport is cheapest. 

 The drifting of single logs, sleeper-pieces, &c., can be begun 

 anywhere, merely by launching them into the bed of a stream, 

 breaking up any obstruction that forms on the way down, 

 relaunching stranded logs, and collecting them at some depot 

 lower down ; but rafting can only begin at some convenient 

 depot, such as land at the junction of two streams, or where a 

 road or a timber-slide ends. Loose drifting is cheapest, but 

 there is more risk of jamming and waterlogging, the average 

 loss varying up to 5 per cent, and sometimes more. A fall of 

 1 to 2 per cent, a depth of 2 to 3 ft. of water, and a minimum 



A Flume or Water- Shoot. 



