FLUMES AND THEIR STRLC1UKE. 101 



tained without much expense. The modus operandi of 

 hoisting these great trestle sections is clearly illustrated 

 in Figure 31, which is a sceiie taken by photograph dur- 

 ing the construction of a high flume near San Diego, 

 California. As a general rule such structures as this 

 are not practicable. 



The great bench flume on the High-line canal in 

 Colorado is illustrated in Figure 32. This flume is 

 twenty-eight feet wide, seven feet deep, and is set on a 

 grade of from five to eight feet to the mile, its total 

 length being 2640 feet and its capacity 1184 second feet. 

 The timbers supporting the flooring are sufficiently 

 heavy and abundant to render the work substantial, 

 while the sills supporting it are well braced and framed. 

 The side braces supporting the uprights are peculiarly 

 and expensively housed by letting them into iron castr 

 ings or shoes at either end. These shoes, bolted to the 

 woodwork of the flume, cannot be said to have increased 

 the life of the structure, as they have caught rain or 

 leakage water and have thus added greatly to the deteri- 

 oration of the wood. 



Pluming Across a River. Another notable 

 flume is shown in Figure 33. It is the wooden flume 

 across the Pecos river in New Mexico. The bottom of 

 this great flume is 40 feet above the river bed, it is 25 

 feet wide in the clear, 8 feet deep, 475 feet long, and 

 rests on substantial trestle work with spans ]6 feet in 

 length. Across the river bed this flume is founded on 

 cribs drift-bolted to the solid bed rock of the river and 

 filled with rock. The abutments of this flume at its 

 junction with the canal, which runs on top of the terre- 

 plein, consists of wooden wings set back a distance of 12 

 feet into the earth, well braced, and supported on anchor 

 piling and filled with earth. The planking of these 

 wings is two inches in thickness. The flume rests on 

 five sets of 12x12 timbers forming each bent of the tres- 



