FOREST-TRAMWAYS. 835 



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 Construction. 



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 forest-roads will suffice 



Fiir. 2i>7. Kail. Fi<r. 20S. Iron sleeper. 



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% though 

 moderate gradients from to 6 % are preferable. The sharpest 

 curves should have 60 to 100 feet radius. 



For the 'main and secondary lines, earthworks to improve 

 the gradient cannot be dispensed with, but the portable 



. 2H'.). Portable pair of rails. 



portions of the railway must run according to the lay of the 

 ground. 



(b) Rails and Sleepers. Flange rails (Fig. 207) 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. 208) are required, 

 and these sleepers are strongly and permanently united to 

 a pair of rails, constituting a section as in Fig. 209. The 

 rails are 6 to 8 meters long in the main lines, but only 2 meters 

 long on the portable lines, and a section must not be heavier 



