RURAL ENGINEERING. 883 



fllliug up of irrigation cauals and the cliokiug of lieadworks. He considers 

 the danger of the silting up of such reservoirs to be negligible. 



Water for irrigation and stock, J. C. Bbunnich {Queensland Agr. Jour., n. 

 ser., 2 (1914). Xo. H. pp. -iOG-^lO). — Notes are given on water in general and on 

 the conditions under which waters are suitable for irrigation and stock watering. 



Economical duty of pumps, F. H. Carter (Engin. Rcc, 10 (1914), Xo. 2.3, pp. 

 618-620. figs. 4). — The author gives an analysis of the co.st of pumps and pump- 

 ing engines and comparisons between special tests and every-day duty. Dia- 

 grams are presented showing the estimated cost of steam pumping engines, the 

 economic duty of pumping engines, and means of finding the comparative 

 economy for pumping engines of different duties. 



A report on the methods and cost of reclaiming the overflowed lands 

 along the Big Black River, Mississippi. I.. A. Jones, W. J. Schlick, and C. E. 

 Ramsee (U. S. Dept. Agr. Bid. 181 {1915), pp. 39, pis. 11, figs, i.9).— This report 

 is based on a survey of the overflowed lauds along the Big Black River, which 

 was finished August 15. 1913. It describes briefly the conditions found, dis- 

 cusses the drainage problems encountered, and presents the plan of drainage 

 considered most practicable. 



The area to be improved comprises 133,460 acres of bottom land bordered by 

 rough rolling land and steep hills. The valley has a fall of 3 ft. per mile at the 

 upper end of the district which gradually decreases to 1^ ft. at the lower end. 

 The soil of the Big Black bottoms is very uniform in texture and is composed 

 of a silty loam underlain by clay. 



From studies of run-off in watersheds similar to and in the same general 

 locality as the Big Black watershed, the following formula of the Murphy type 

 was deduced upon which the design of all levee improvements was based : 



0_ 18700 



Q=discharge in second-feet from each square mile and l/=the watershed area 

 in square miles. For computing the size of all ditches the following formula 

 was deduced : 



M 



The general plan as proposed for the drainage of the Big Black River bottoms 

 consists of the construction of a main ditch and of the necessary laterals at 

 the upper end of the valley, the construction of levees, the clearing of a flood- 

 way through the bottoms, including the present river channel, and provision 

 for interior drainage by the construction of ditches and the clearing of present 

 channels. 



" In computing the sizes of ditches and levees and the capacities of the flood- 

 ways, the Chezy formula. v=c-y/rs, was used. In this formula c is ... de- 

 termined by Kutter's formula, in which the coefficient of roughness, n, was 

 taken at 0.030 for ditches, 0.035 for cleared channels, and 0.040 for floodways. 

 To provide a margin of safety, ditches were given a depth of 1 ft. greater than 

 that computed as necessary to handle the discharge. The tops of the levees 

 were taken at 3 ft. above the high-water line as computed. . . . 



" To carry out this work 3G drainage districts are planned, having a total 

 area of 96,088 acres. The estimated cost of this work, exclusive of that of 

 clearing the main floodway, varies in the different drainage districts from 

 $15.72 to $44.36 per acre, the average cost per acre for the entire 36 districts 

 being $23.06." 



Tables of run-off data, bench-mark locations, and a number of maps of the 

 proposed improvements are appended. 



