iOlG] RUBAL ENGINEERING. 491 



for iiiaiiitenance, except at a few places on some of the first work where drain- 

 ai?e inlets were not constructed at the time the lining was placed. The fric- 

 tion factor for this kind of lining as determined from experiments varies 

 from n=0.01 for canals having a straight alignment and perfectly free from 

 shifting sand and pebbles on the bottom to n=0.015 for canals having numer- 

 ous curves and a limited amount of moving sand along the bottom. No 

 trouble has been experienced on account of expansion or contraction injuring 

 the lining, even when the water is rotated and the canal is dry half the time 

 during the summer." 



Comparison of wood and concrete for use in irrigation structures, S. T. 

 Harding {Enr/in. and Contract., J,5 (1916), No. 15, pp. 340-342).— This report 

 deals with the factors involved in a choice between concrete and wood for 

 irrigation structures. 



It is concluded " that no general conclusions can be drawn as to the most 

 economical type of construction. For any particular project where the con- 

 struction costs can be estimated and the other factors, such as financial con- 

 ditions of the constructing organization, rate of interest, certainty as to type 

 of structure desired, and permanence of its location, can be given proper 

 weight, a decision can be made. Under usual conditions concrete will be the 

 preferable material if the capitalized cost of service alone is considered. 

 The other factors are, however, more usually such as to incline the choice 

 toward wood for first construction, except for the larger and more important 

 structures. That the capitalized cost is being given more consideration and 

 that many systems are reaching a condition where replacements and better- 

 ments can be made on a more permanent basis is evidenced by the increasing 

 use of concrete in irrigation structures." 



Methods of placing' and cost of concrete lining in laterals on Orland 

 Project, A. N. Burch (Rcclani. Rec. [U. S.], 7 (1916), No. 4, pp. 178, 179, figs. 

 3; abs. in Engin. and Contract., 45 (1916), No. 15, p. 352). — Up until February, 

 1916, there have been lined about 22 miles of laterals on the Orland Project, 

 in sections ranging from a few feet in length and requiring less than a cubic 

 yard of concrete to a maximum section of 8,800 ft. The cross sections of 

 the laterals lined have ranged from a bottom width of 2 ft. and vertical depth 

 of 1 ft. to a bottom width of 8 ft. and vertical depth of 4.5 ft. Laterals 

 originally designed for lining were built with 1 : 1 bank slopes ; other laterals 

 with 1.5 : 1 and 2 : 1 slopes. " The aggregates used are run of bank material 

 obtained from creeks in the vicinity of Orland. The proportions of mix are 

 approximately 1:3:5. . . . There is little difference in the cost of lining 

 whether the material be hand or machine mixed, although the machine turns 

 out a better and more uniform grade of concrete." 



The total cost per square yard of this work has been 34.3 cts. 



Irrigation management, F. H. Newell {New York and London: D. Appleton 

 d Co., 1916, pp. XIII-\-306, pis. 8). — This is a summary of information on 

 methods of operation, maintenance, and betterment of irrigation works. It 

 contains chapters entitled the problems ; the physical conditions ; tlie human 

 element ; the legal side ; operation organization ; methods of operation ; records 

 and schedules ; water economy ; maintenance ; expenditures, recording, and 

 classifying ; receipts and values ; the irrigator and his associations ; methods of 

 applying water ; the products ; and conclusions. 



The cost of tile drainage on the Trumbull County experiment farm, H. L. 

 Andrew (AIo. Bui. Ohio i<ta., 1 (1916), No. 5, pp. 136-140, figs. 2).— The costs 

 of tile draining 110 acres of land, which included a total of 7,959 rods of ditch, 

 averaging 30 in. in depth, and 123,541 tile in 3, 3^, 4, 5, 6, and 7 in. sizes laid 

 from 33 to 40 ft. apart, are summarized. The cost per acre averaged 8 cts. 



