134 IRRIGATION FARMING. 



6x12 timber, and on them are nailed 2-inch floor 

 planking placed at right angles to the current. The- 

 side bracing of the flume consists of 6 x 8 scantling 8 

 feet in length, though at present these are planked for 

 a depth of only 5 feet, giving the flume that available 

 depth. These pieces are placed 4 feet apart between 

 centers and are braced by short struts at each bent of 

 the trestle. 



The Arc Stave Flume. — A comparatively new 

 idea is the arc flume which is being used quite exten- 

 sively throughout the Rocky Mountain region west of 

 the Continental Divide and along the Pacific coast. 

 This flume is semicircular in shape, and is formed of 

 redwood or pine staves bound with steel bands, fast- 

 ened to tie-beams across the top. The staves are 

 quarter-sawed from 2x6 inch sticks. The tie-beams 

 are 4x4 inches, so that when built the flume is a 

 stiff, water-tight, half-round trough, supported at in- 

 tervals of eight feet by wooden saddles. No nails are 

 used in the flume, and it is easily and cheaply adjusted 

 to any condition of humidity by means of nuts at the 

 ends of the iron bands, much like those used for the 

 circular stave pipes. The Mount Nebo Irrigation 

 Company in Utah is using this system. The reservoir 

 is over six miles long, and holds more than a bil 

 lioncubic feet of water. The dam is 44 feet high, 

 330 feet long, and no feet wide at the bottom. A 

 tunnel 140 feet long, through solid rock, some distance 

 away from the dam, furnishes an outlet for the reser- 

 voir. In condudling the water down Currant Creek 

 Caiion a large flume crosses on high trestlework, and 

 some distance below where it was necessary to cross 



