PROTECTIVE WORKS. 



619 



apart, are dug all over the area, being arranged like the 

 wattle-fences in Fig. 281 ; their construction on very steep 

 slopes is evidently not unattended with danger. 



e^S;4iS^{j-i>«& 



si&^si^s-aP&Q^' 



Fig. 281. — rian of fences for protection against avalantlies. 

 a h. Line where the avahinches commence, c. Fences. 



{}>) lions of Wattle -Fence a. — The stakes used may be eitlier 

 of wood or iron. Tliese are set up at intervals of from 20 to 

 50 feet, their central points being at those of a series of 



Fig. 282. — Dry masonry wall for protection against avalanches. 



equilateral triangles ; they should be 15 to 30 feet long, and 

 of watlle-work with branches plaited between stakes jfirmly 

 driven into the ground. 



Such a system of wattle-fences allows soil to be formed on a 



