153 Proceedings oE the 



tion to convince the settler of the importance to his 

 welfare of a continued lumber and fuel supply. The 

 great value to the settler and the settler's live stock, 

 of the shade and shelter afforded by the trees of the 

 forest and woodland are fully appreciated. Even the 

 aesthetic and sanitary value of forests are not over- 

 looked. 



Related to the above is the influence of forests on 

 irrigation construction. This may not be obvious to 

 the average person, but the tendency of modern con- 

 struction is to the use of the more permanent materials, 

 less subject than wood to destruction and decay. This 

 is facilitated by the development of the useful proper- 

 ties of concrete, iron, and steel, and their combinations. 

 The Reclamation Service in particular is endeavoring 

 to build, "not for a day, but for all time," and the 

 wooden gate, the wooden flume, and other structures 

 so much in evidence in the past are to be entirely 

 superseded by more permanent materials. 



To this end, massive gates of cast iron and bronze, 

 set in abutments of concrete, are being introduced. 

 Experiments have been made on reinforced concrete 

 for use in pressure pipes and flumes, and the wooden 

 dam is' being superseded by that of concrete, masonry, 

 or earth. To the same end the proportion of tunnels 

 is increased, underground conduits being the safest and 

 most permanent yet devised. 



The effect of such a policy upon the consumption of 

 wood is not, however, so great as might be supposed, 

 especially in the construction period. The require- 

 ments for timber are still very great for piling and 

 subaqeous structures to which wood is well adapted, 

 and for buildings and the large class of temporary 

 structures required on great irrigation works. No 

 satisfactory substitute has yet been found for timber in 



