322 



WOOD TRANSPORT BY LAND. 



simply wedging together two vertical and one horizonta 

 planks, each measuring 13 feet X 12 inches X 5 inches, into 

 block-sleepers. It was used for broad-gauge railway-sleepers, 

 which fell into a deep part of the river Tons. This slide was 

 1 mile 1,052 feet long and the fall 2,687 feet, the average 

 gradient being 2 in 9 or 22 per cent. Brakes formed of 2 and 3 

 inch planks placed 15 feet apart were used to stop the velocity 

 of the sleepers, but this proved of no avail and the slide was 

 then divided into two sections, the steeper part being covered 

 in with planks. A little water was admitted to prevent the 

 wood from taking fire, which eventually happened to the lower 



Fig. 200. Plank-slide. 



part of the slide, down which the sleepers went with great 

 velocity. Tr.] 



Plank-slides are used extensively in the Black Forest. If 

 plank-slides are to be used for the export of large quantities 

 of timber they must be constructed strongly, but when only 

 for temporary use, the sections are lightly built and portable, as 

 shown in Fig. 200. In this case the ends of the planks are 

 sloped off and fastened by screws to those of the next section. 

 These portable slides are used for firewood in the Sihlwald, 

 near Zurich. 



(c) Wet Slides. The description of slides will be completed 

 by an account of wet slides, which must be made as nearly 

 water-tight as possible, so as to hold a moderate stream of 

 water; therefore they must be constructed much more carefully 

 than dry-slides. 



