TIMBEB-8LIDE8, 



317 



on strong wooden supports, which may be termed block- 

 sleepers, and are made of different shapes. Owing to the 

 great weight of the slide that naturally tends to drag it 

 down-hill, this tendency being increased by the shaking to 

 which it is subject whilst sliding is in progress, the block- 

 sleepers must be supported by props on both sides to keep 

 them steady. Only when the block-sleepers are sufficiently 

 massive to preserve their own stability can these props be 

 dispensed with. The lowest section of a slide is made very 

 strong to resist shocks, and is either horizontal or inclined 

 upwards, in order to moderate the fall of the wood as it slides 

 down. It should rest on strong blocks of wood driven into 



Fi.L'. 193. Timber-slide. 



the ground, and the effect is to shoot the descending piece of 

 wood upwards in a curve, so that it may fall without any 

 great shock (Fig. 1!W). 



Asa rule (Fig. 193), each section consists of six poles, two 

 (a a) forming its base, two (b 1>) the sides, and two (c c) the 

 edges of the slide. In curves, one of the pieces c. may be 

 omitted on the inner side. Where the gradients are very steep 

 a second pair of poles (d d) may be added. The pieces of 

 wood on the inside of the slide are all barked. 



The sections of the slide are joined together as shown 

 in Fig. 194. The pieces a a fit into the groove of the 

 block-sleeper (Fig. 195), the pieces b b rest between the 

 former and pegs driven into the block-sleeper, and c. c on 

 these pegs and two others similarly fixed ; they are kept 



