4 BULLETIN 155, U. S. DEPARTMENT OF AGRICULTURE. 



is not so subject to injury from freezing, settling, or expansion and 

 contraction due to extremes of temperature, while if injury is sus- 

 tained, extra material can usually be obtained readily, and repairs can 

 be made much more quickly and with less expense than would be re- 

 quired for pipes of iron or steel. Furthermore, the capacity of wood 

 pipe is probably somewhat greater than that of iron or steel of equal 

 size, and may. under favorable conditions, increase with time instead 

 of being reduced by tubercles and corrosion such as occur in the other 

 kinds of pipe mentioned. 



More continuous stare pipe has been used for conveying municipal 

 water supplies than for any other purpose. The Denver Union 

 Water Co. has been using it since 1884, and now has upwards of a 

 hundred miles installed. Seattle has over 50 miles: Tacoma com- 

 pleted about 43 miles in 1912 and has built more since that time ; the 

 Butte City Water Co., prior to 1899, had installed about 30 miles; 

 Walla Walla. Wash., has 13 miles. It is used to some extent at 

 Astoria. Oreg. ; Salt Lake City, Ogden, and Provo, Utah: Canon 

 City. Pueblo, Loveland, Trinidad, and Fort Collins, Colo.; and in 

 many other places in the West that might be mentioned, as well as at 

 a few in the Atlantic States. 



The use of this type of pipe in connection with power development, 

 though as yet perhaps not so extensive, is coming to be even more 

 general than for conveying municipal water supplies, and examples 

 might be enumerated by the hundred of pipes in sizes from 2 feet to 

 14 feet in diameter that have been installed for this purpose through- 

 out the United States. Canada. Mexico, and Alaska. 



The use of wood pipe for irrigation purposes is confined to the 

 Western States, but there are few of the more important irrigation 

 projects of recent development on which it is not employed at least 

 to some extent, its chief adaptability being for "inverted siphons" 

 for carrying water across deep ravines or depressions not otherwise 

 easily spanned. In a few instances the original gravity ditches have 

 been entirely supplanted by continuous stave pipe. It is also very 

 frequently used for conducting water from pumps to the points of 

 discharge into ditches or reservoirs at higher elevations. 



Continuous stave pipe has. as a rule, been restricted to service where 

 the pressure head does not exceed 200 feet, though in many instances 

 short sections are required to carry greater pressures rather than 

 change to another type of pipe. A few pipes of this kind have been 

 built for heads up to 400 feet. 



DESIGNING OF CONTINUOUS STAVE PIPE LINES AND MATERIALS USED IN 



CONSTRUCTION. 



A discussion of the theory underlying the many considerations of 

 the economic design of wood-pipe lines is not within the scope or 



