68 BULLETIN 126, U. S. DEPARTMENT OF AGRICULTURE. 
1 barrel of cement to 7 full barrels of the same size of aggregates when mixed together. 
If broken stone is used, it must be hard, clean, and heavy, having at least a specific 
gravity of 2 and screened into three different sizes. None of the gravel is to exceed 
2 inches in diameter. The mixture of such sizes will be in the proportion determined 
by the engineer. All of the rock must be of such size that it will pass through a screen 
with a 2-inch square mesh. 
The seam shown in Plate IX, figure 1 , is t}^pical of many such seen 
in canal lining in that it gradually diminishes in width from the top 
to the bottom of the side lining. Plate IX, figure 2, shows a fracture 
extending not only through the concrete but also through a diabase 
rock some 14 inches long and 4 to 6 inches thick which was embedded 
in the concrete. The natural cleavage of this rock, it may be observed, 
was nearly at right angles to the rupture as made by the contraction 
of the concrete. 
The placing of the concrete Lining against the uneven rock surface 
served to anchor the lining and prevent contraction, and this same 
foundation condition doubtless added much to the strength of the 
lining as a whole. Notwithstanding this fact, however, ruptures 
have occurred at intervals of 28 feet or more throughout the lining. 
The seams created by these ruptures varied in width from one- 
twelfth to one-half inch or more at a time when the temperature of 
the air was 50° and that of the water in the canal was 42° F. 
LOWER YAKIMA IRRIGATION CO., RICHLAND, WASH. 
The canal of this company parallels the Yakima River for several 
miles, where the earth sections run mainly through coarse gravel, 
bowlders, or shattered basaltic rock. The remainder of the system 
is very largely built through sand. In the unlined channel the seepage 
losses were excessive, and through the sand it was also difficult to 
maintain the ditch owing to its tendency to fill up both by drifting 
and on account of the flat side slopes which the sand naturally as- 
sumed under the action of water. The fining was intended, there- 
fore, not only to reduce the loss of water but to increase the carrying 
capacity of the ditch and render it more stable and easy to maintain. 
About 5 miles of the ditch was fined in 1910. The company furnished 
all materials used and prepared the channel for fining, but the other 
work was done by contract. 
In preparing the ditch, center stakes were set about 1§ inches 
above grade, to which the excavating was roughly done with teams 
and scrapers. At intervals of about 25 feet along the bottom of the 
side slopes stakes were set to grade, and from these the top slope 
stakes were set by the use of a slope triangle. Nails were driven 
into the grade stakes and chalk fines were stretched on them parallel 
to the ditch. Trimming to these fines was done then with square- 
pointed shovels and the slopes and bottom scraped to smooth sur- 
