1917] 



BUBAL ENGINEEEING. 



285 



Brake and water horsepower and efficiency tests of three centrifugal pumps 

 are reported in the following table : 



Brake and water Jiorsepower and efficiency of centrifugal pumps. 



Kind of pump. 



Head on 

 pump. 



Effi- 

 ciency. 



Feet. 



3-in. horizontal centrifugal 10 



To 25 



Do 50 



5-in. vertical (submerged) 10 



Do 25 



Do 50 



7-in. vertical centrifugal (submerged) 10 



Do 25 



Do ! 50 



Per cent. 

 36.6 

 47.5 

 50.7 

 49.2 

 54.2 

 5&7 

 43.6 

 63.6 

 71.3 



Growth of moss in irrigation canals, Salt River Project, A. J. Haltom 

 (Reclam. Rec. [L\ S.], 8 {1911), No. 4, pp. 191, i92).— Studies of the growths 

 of moss which obstruct the flow in the wide, shallow, low-velocity canals of 

 the project led to the following conclusions : 



" Moss does not grow in canals of high velocity. Neither does it flourish in 

 canals that have uniform grades, but canals of uneven grades which contain 

 low spots are very favorable for healthy growth. Moss does not grow in the 

 absence of sunlight. It does not grow in canals with water depth of more than 

 5 ft. It flourishes be.st in canals with a silt bottom because the silt furnishes 

 an excellent medium for root development. It obtains its healthiest growth 

 in clear water. Muddy water retards but does not completely stop its growth." 



The best results in experiments on control " were obtained with an Acme 

 harrow. This machine was used with such satisfactory results that it is 

 highly recommended for the removal of moss under conditions similar to those 

 on this project." • 



Control of moss, weeds, and willows on the Minidoka Project, B. Dibble 

 and T. W. Parry (Reclam. Rec. [U. S.], 8 (1917), No. 4, pp. 192, 193, fig. 1).— 

 In experiments on the control of moss and weeds on the project during June 

 " the only method which was found successful in clearing the moss from the 

 larger canals was by cutting with the Ziemsen .submarine saw. 



" This saw consists of a flexible band of steel with hooked teeth on both 

 edges. It can be obtained in any length, and the weights to hold it to the 

 bottom are adjusted to fit the canal. It is operated at an angle of about 30° 

 with the cross section of the canal, the crew always working upstream. The 

 rate of progress is from 6 to 12 in. at each double stroke and from 0.25 to 1 

 mile per day can be cut with each saw. The long streamers of moss when cut 

 rise to the surface and float down to the next bridge or check, where they are 

 thrown out by men with pitchforks. . . , 



" Where it can be done the cheapest and most effective method of cleaning 

 the canal is to shut the water out entirely and let the ditch dry in the sun. 

 Five to seven days' exposure is necessary ordinarily to kill the moss. This 

 method kills the growth, but does not destroy the bulb. . . . 



" During the 1916 season 260 miles of cleaning were done. The total cost 

 of this work was $4,200, making the cost per mile a fraction over $16. The 

 average cost per mile of the different methods is about as follows : Sawing 

 $22, chaining late in the season $8, cutting with scythes in laterals $11, and 

 spring-tooth harrow in laterals $9. . . , 



