308 WOOD TRANSPORT BY LAND. 



Steep gradients should be avoided always for cart- traffic, not 

 only to facilitate the latter, but also to protect the road, which 

 when steep is liable to much injury from the use of the brake 

 and owing to erosion by water. Sledge-roads, on the contrary, 

 require a steep gradient and have been constructed recently in 

 a most perfect form in high mountain-regions, being made of 

 two kinds for sledges drawn by men or animals ; they may be 

 termed feeders and main sledge-roads. The latter are confined 

 to the lower ground ; traverse long valleys, and serve for 

 conveyance of the wood to depots. The feeders descend the 

 mountain-slopes from the highest and most inaccessible parts 

 of the forest, they often wind round all kinds of obstacles, 

 rocks are blasted to make way for them, galleries cut along 

 precipices and tunnels bored. By their means the wood is 

 brought down to the main sledge-roads. Wherever sledge- 

 roads run through cuttings in districts with heavy snowfall, 

 they must be covered with rafters and spruce branches for 

 protection. The gradient of the feeders should not be less than 

 6 to 8 per cent., or greater than 18 to 20 per cent., though 

 even the latter is sometimes exceeded, but 12 to 15 per cent, 

 are the usual gradients. The main sledge-roads are less steep, 

 and 8 to 12 per cent, are usual gradients, but even a slight 

 ascent cannot always be avoided in their case where a ridge 

 has to be crossed between two valleys. 



Ground timber- slides are used extensively in the eastern 

 Schwarzwald; they may be used also as sledge-roads chiefly for 

 the transport of logs. Their gradient should lie generally 

 between 9 to 12 per cent., and may go up even to 18 per cent. 

 A steady gradient is more necessary in the case of sledge- 

 roads than on roads for wheeled traffic ; in the latter case, 

 now-a-days it is considered better to vary the gradient, as this is 

 loss tiring to beasts of draught than a uniform gradient which 

 always calls on the same muscles. 



(h) Breadth of Roads. The breadth of forest-roads 

 depends on the mode of conveyance used, and the amount 

 of traffic. Main forest-roads should not be less than 18 to 

 24 feet broad, if the traffic on them is not to be impeded, 6J 

 to 8 feet being the width between the wheels of a cart. 



The subsidiary roads need not have a greater breadth than 



