1917) EURAL ENGINEERING. 487 



nuring the falling stage of the river, the maximum percentage of silt is carried 

 at a somewhat higher discharge. The maximum percentage of silt by weight 

 observed is 4.16 per cent. Tlie mean silt content and percentage by weight, 

 1909 to 191G. of the Colorado River at Yuma, without the Gila flow, is 0.7 per 

 cent. At times of Gila discharge tliis percentage is 0.93. The weight of the 

 wet deposited silt per cubic foot when dried is 86 lbs. The weiglit of 1 cu. ft. of 

 solid dried silt is 159.3 lbs. The specific gravity of the silt is 2;6." 



Sluicing" silt to reduce canal leakage, F. J. Barnes {Engin. News-Rcc, 78 

 {1917), No. 7, pp. 337-3S0, figs. S). — This article summarizes operating experi- 

 ence on an experimental plant installed on the U. S. Reclamation Service 

 Irrigation Project at Grand Valley, Colo. 



Modern practice in wood-stave pipe design and suggestions for standard 

 specifications, J. F. Partridge (Proc. Arncr. Soc. Civ. Engin., 43 (1917), No. 4, 

 pp. 559-594) . — "The object of this paper is to give engineers an idea of the 

 difference between the various grades of wootl pipes; to set forth a standard 

 set of specifications for the assistance of engineers who have hud no oppor- 

 tunity to become versed in their design; to safeguard those who contemplate 

 building such pipe ; and to remove doubt from the minds of those who view 

 wootl pipe as one of the vagaries of engineering practice and a medium to be 

 resorted to only in temporary and cheap work." 



The elements causing success or failure in wood stave pipe are enumerated 

 as (1) iiinds of wood used, (2) grade of lumber used. (3) method of curing 

 lumber. (4) method of treating lumber, (.5) location of pipe when built, (6) 

 size and spacing of bands, and (7) methods used in erection, and quality of 

 woriimanship. These are discussed as applied to continuous-stave pipe and 

 machine-banded pipe, and a plea is made for the adoption of uniform specifica- 

 tions, dividing each type into classes A, B, and C. The appendix contains the 

 specifications for the two types and three classes of pipes, which are proposed 

 as a basis for adoption by engineers. 



The clas.sification of continuous-stave pipe is as follows : " Class A — a pipe 

 liaving a maximum life, under all conditions, and this will be 25 years when 

 receiving no care whatsoever; a life greater than 25 years, if under continu- 

 ous operation; and a probable life of 50 years, or more, if in continuous opera- 

 tion under at least a moderate head, if the bands are given attention and cor- 

 roded ones are renewed. This includes pipe made from clear, air-dried red- 

 wood. Class B — this class includes coated pine or fir, in such a situation as to 

 be open to continuous inspection, so that it may be given constant attention; 

 comprising repainting staves and renewing bands. This pipe will be placed 

 under class A, on theory only, as experience has not yet confirmed such an 

 assumption. Class C — this class will have a maximum life of 10 years and an 

 average life of 7 years. It will include uncoated fir, pine, or other suitable 

 wood." 



The classification of machine-banded pipe is as follows : " Class A — this 

 class will have a life of from 15 to 25 years when receiving no attention; a 

 longer life under ideal conditions, as when laid in soils having the least pos- 

 sible corrosive effect on the galvanized wire, and when operating under pres- 

 sure, so as to insure complete saturation of the wood. Pipes of this class will 

 be guaranteed to withstand severe conditions of overload, such as in hydro- 

 electric work, general waterworks for city supply, and high-pressure pumping 

 lines; and will be guaranteed to withstand an overload of 100 per cent under 

 test. It will include pipes of clear, air-dried redwood, manufactured accord- 

 ing to the specifications in the appendix. Class B — this class will have a life 

 of at least 10 years, and a probable life not exceeding 15 years. It will include 

 12883°— 17--NO. 5 7 



