FOREST-TRAMWAYS. 



341 



and that those sections of the tramways which reach the felling- 

 area should he of light portable nature. 



It is evident that in certain cases the line cannot be continued 

 up to the felling-area, whilst in other cases the portable parts of 

 the tramway communicate directly with the permanent way, and 

 the half-portable portion is not required. In fact, all lines 

 do not include the three kinds of tramway already mentioned. 



2. Mode of Const ruction. 



This includes laying-out the road, the rails and sleepers, the 

 rolling-stock and apparatus used for loading the trucks. 



(a) Laying-out the Road. — Ordinary lorest-roads will suffice 

 for the main tramways and the half-portable way. They should 

 be as straight as possible, and there should not be much range 

 of gradient, which may reach 8 or 10 " 1^, though moderate 

 gradients from to 6 % ^^'^ preferable. 



For the main and secondary lines, earthworks to improve the 



Fig. 179. 



Fig. ISO. 



gradient cannot be dispensed with, but the portable portions of 

 the raihvay must run according to the lay of the ground. 



(b) Rails and Sleepers. — Flange rails (fig. 179) of the best 

 Bessemer rolled steel are used. Transverse sleepers only are 



used. For the main lines wooden sleepers are used, but for the 

 portable portions of the line steel sleepers (fig. 180) are re- 

 quired, and these sleepers are strongly and permanently united 

 to a pair of rails, constituting a section as in fig. 181. The 

 rails are 4 to 6 meters long in the main lines, but only 2 meters 



