586 EXPEEIMENT STATION RECORD. [Vol.37 



With regard to cost, it is stated that " a first-class pumping plant, including 

 well, may be installed, under average conditions of head and capacity, at a 

 cost of from $5,000 to $7,000, with ample capacity to irrigate 160 acres of 

 average forage crops. A smaller plant with a capacity of several hundred 

 gallons a minute may be installed complete, including the well, for $2,000 or 

 less if water-supply conditions are favorable. The cost of a reservoir may be 

 $500 or even $1,000 if it be concrete lined. The operation of a pumping plant 

 should extend over as great a period of time during an irrigation season as 

 possible, so as to reduce the unit overhead cost." 



Divisors (for the measurement of irrigation water), V. M. Cone {Colorado 

 Sta. Bui. 228 (1917), pp. S-52, figs. 8). — This bulletin, based on work done under 

 a cooperative agreement between the Colorado Station and the Office of Pub- 

 lic Roads and Rural Engineering, U. S. Department of Agriculture, reports the 

 results of 341 tests of divisors for the measurement of irrigation water and 

 196 tests on dividing the flow over rectangular and Cipolletti weirs. Eight 

 different divisors were tested, each under four different sets of conditions. 



In the weir tests " crest lengths of 2 and 4 ft. were used for both types. A 

 thin metal plate was placed on the downstream side of the weir so that its 

 edge touched the crest of the weir and extended vertically above the weir crest 

 into the weir notch. This plate was set for different experiments at intervals 

 of 2 in. across the entire width of the weir, and separate channels caught the 

 flow over the weir on the two sides of the plate. These channels were placed 

 far enough below the crest of the weir to allow a free passage of air under the 

 overpouring sheet of water. 



" Under these conditions both types of weirs give reasonably accurate di- 

 visions, the greatest error being with the rectangular weir sot to divide the flow 

 between two parties on a basis of one-fourth and throe- fourths, wlion the actual 

 deliveries will be 24 and 76 per cent for a head of 0.2 ft., and 22.5 and 77.5 

 per cent for a head of 0.8 ft. The errors with Cipolletti weirs used as divisors 

 were in the opposite direction and about one-half as great. When either weir 

 would be used to divide the water equally between three parties the error would 

 be quite negligible. 



" If the divisor plate Is placed out some di.stance from the weir, or the edge is 

 placed in a horizontal position below the weir crest, the discharge for the end 

 division would be considerably short, and the flow for the middle division 

 would be accordingly greater than the desired amount." 



The composition of irrigation waters in upper Italy. A. Menozzi and A. De 

 Vecchi {Rend. R. 1st. Lombardo Set e Let., 2. scr., ^9 {1916). No. 7-8, pp. 291- 

 297). — Analyses of representative samples of irrigation waters from irrigation 

 canals of Lombardy are reported and discussed. 



The economical irrigation of alfalfa in Sacramento Valley, S. H. Beckett 

 and R. D. Robertson {California Stn. Bui. 280 {1917), pp. 273-291 figs. 2).— 

 This bulletin reports the results of work done under cooperative agreement be- 

 tween the Office of Public Roads and Rural Engineering, U. S. Department 

 of Agriculture, and the State Engineering Department of California, and be- 

 tween the Office of Public Roads and Rural Engineering and the California 

 Experiment Station. The practices found most desirable are summarized in 

 the table following. 



