886 EXPEKIMENT STATION EECOED. 



" The influence of velocity is relatively small. This is chiefly due to the fact 

 that sediment can not be deposited \A'hen the mean velocity exceeds a rather low 

 limit. Of the two factors, sedimentation and velocity, the former exerts the 

 greater influence in lessening seepage losses, so that any increase in velocity 

 which tends to prevent sedimentation is detrimental rather than beneficial." 



A report along similar lines by the author has been previously noted (E. S. R., 

 32, p. 380). 



How to express seepag-e losses from irrigation cana?s, S. Foktieb (Engin. 

 News, 73 (1915), Uo. 23, pp. 1128, 1129).— The author contends that seepage 

 losses expressed in feet-depth over the Vv'etted area in a given time should be 

 confined to flooded areas on irrigated fields, reservoirs, checked-up water 

 courses, and, in general, to water surfaces v/here the loss can be measured di- 

 recently, and not to water in motion. Instead, he advocates that seepage losses 

 be expressed as percentage loss of flow. 



In pursuing this course, it is stated that the engineer should carefully study 

 all conditions which are likely to affect the escape of water from the canal. 

 " These should include the amount of sedimentation per season and its effect on 

 the character of the material, the tfTidency to scour under high velocities, fluc- 

 tuations in depth, velocity and extent of wetted surface, inflow of seepage water 

 from higher irrigated lands, evaporation from wet banks and water surfaces, 

 transpiration from tree growths, leaks from structures, aquatic vegetation, the 

 temperature of the water carried as well as that of the soil, and the location of 

 the water table either beneath or adjacent to the canal. After a comprehensive 

 study of existing and possible future conditions, together with all of the avail- 

 able data pertaining to the seepage losses from canals of like capacity traversing 

 materials of like character as regards porosity, he will be in a position to estimate 

 with reasonable accuracy the percentage of loss due to seepage, which may be 

 expressed either in second-feet per mile or in percentage of the flow per mile." 



Methods of plaster lining irrigation canals and laterals, Okanogan project, 

 IT. S. Reclamation Service (Engin. and Contract., Jf3 (1915), No. 20, pp. 4^1- 

 41)3). — This paper discusses • methods of construction, cost, and efficiency of 

 plaster lining for irrigation canals and laterals. From observations of the 

 lining done on the Okanogan project, it is stated that the seepage loss in lined 

 sections has been very small. The lining has cost from 5.1 to 6.4 cts. per 

 square foot. 



The use, design, construction, cost, and durability of wooden stave pipe, 

 A. SwiCKAED (Engin. and Contract., 42 (1914), N'os. 19, pp. 422-424, figs. 2; 

 23, pp. 516-519; 43 (1915), Nos. 1, pp. IO-I4. fig.'>. 2: 7, pp. 146-I48, figs. 4; 22, 

 pp. 483-486, figs. 9). — This article, in five parts, deals with the uses and misuses, 

 durability, design, and cost of wooden .stave pipe, and with construction, or- 

 ganization, and methods. Considerable working data for use in design and con- 

 struction are given. 



Tests of submerged orifice head gates for the measurement of irrigation 

 water, F. L. Bixby (New Mexico Sta. Bui. 97 (1915), pp. 3-55, figs. i2).— This 

 bulletin, based on worli done under a cooperative agreement between the station 

 and the Office of Experiment Stations of the U. S. Department of Agriculture, 

 reports investigations the main purpose of which was to calibrate a submerged 

 orifice and prepare tables for its use in measuring water for irrigation. 



The submerged orifice used in the tests was an ordinary sliding head gate, 

 the opening of which was entirely submerged. The orifice box consisted of a 

 wooden flume 7 ft. long, 3 ft. wide, and 2.5 ft. deep, with one side so con- 

 structed as to be readily moved, thus facilitating the regulation of the width 

 of orifice. The gate was located 2.5 ft. from the upstream end of the flume. 



