miner's inches. Cost, $259,020.14. The Eureka Lake Ditch is 18 miles long, and has a capacity of 2500 miner's inches. Its cost, including water rights and flumes, was $430,250. The San Juan

La Grange Ditch.

ditch and branches extend some 45 miles in length. The main ditch is 32 miles long, and its capacity is 1300 miner's inches. Their cost was $293,092. These two last-mentioned ditches belong to the Eureka Lake and Yuba Canal Company.

The main ditch of the South Yuba Canal Company (from the head to Bear River is 14 miles long) is 6 feet wide on top and 5 feet deep, with a grade of 13 feet per mile. Its present capacity is said to be 7000 miner's inches of water. From Bear Valley (the junc

tion of the main and Dutch Flat ditches), the size of the canal for the succeeding 31 miles, is 6 feet wide on top, 4 feet deep, with a grade of 8 feet to the mile. The Dutch Flat Ditch is 13 miles long. Its size is 6 feet on top, 4 feet deep, and has a grade of 13 feet per mile. The capacity of this ditch is 3150 miner's inches of water. The Chalk Bluff Ditch is 6 feet wide on top, and 5 feet deep, with a

grade of 16 feet per mile, and has a capacity of 4100 miner's inches. The several ditches, etc., owned by the South Yuba Canal Company, have an aggregate length of 123 miles. The Excelsior or China Ditch, at Smartsville, is 33 miles long. Size, 5 feet bottom, 8 feet on top, and carries 4 feet of water. The grade is 9 feet to the mile, and the ditch discharges 1700 Smartsville miner's inches. The Bouyer and Union ditches are each about 15 miles long. Size, 4 feet on bottom, 8 feet on top, carrying 33 feet of water. Their grades are 13 feet to the mile, discharging each 1200 Smartsville miner's inches. There are several minor ditches which deliver water in and around Smartsville. The total capacity of all the ditches is 5000 Smartsville miner's inches, and the whole investment in this class of property, in this locality, approximates $1,200,000.

The Spring Valley and Cherokee Ditch is 52 miles long, and has 3 miles of iron pipe, 30 inches in diameter. The size of the ditch averages 5 feet wide, 3 feet deep, discharging about 2000 inches of

water.

The Hendricks Ditch,* in Butte County, is 46 miles long; grade of the upper line of ditch, 12.8 feet per mile; grade of the lower line, 6.4 feet per mile; dimensions, 5 feet wide, 2 feet deep. Total cost, including Glen Beatson Ditch and Oregon Gulch Ditch, $136,150.

The La Grange Ditch,† including Patricksville branch, is over 20 miles in length. Size, 9 feet on top, 6 feet bottom, 4 feet deep.

Grade from 7 to 8 feet to the mile. The greater part of the ditch is cut in granite, and in places there are solid walls 50 to 70 feet

* See Raymond's Report, 1873, pp. 73, 74.

†The original ditch, about 19 miles long, is said to have cost $375,000. Since its completion, the Patricksville Ditch and reservoir have been built at a cost of $75,000.

high, built of stone. It discharges 2700 miner's inches of water, and its cost to date is about $450,000.

GENERAL OBSERVATIONS.

Ditches in California with carrying capacities as large as eighty cubic feet per second have been built, and are now in successful operation, with grades of from sixteen to twenty feet per mile. In a mountainous country, where steep grades can be generally obtained by a slight increase in the length of the canal, and where the cost of excavation is large, a great saving can be effected by using the smallest-sized canals and aqueducts practicable to carry the given quantity of water, or, in other words, by running water rapidly through a small channel rather than slowly through a large one. It is found to be safer and more economical, on account of the deep snows and terrific storms which rage in the mountains during the winter, to run and maintain in repair narrow and deep ditches on heavy grades than broad ones with light grades. The experience of the ditch-builders in this State has been highly favorable to these steep grades, but little trouble being caused by the washing of the banks due to high velocities.* In the valleys with ashy soil such grades, of course, would not be practicable.

These narrow ditches with steep grades do not discharge within 25 to 30 per cent of the amount of water given by the formulæ for "the discharge of water in canals."

FLUMES, AND THEIR CONSTRUCTION.

In crossing ravines, flumes or wrought iron pipes are used. Many miners object to flumes on account of their continual cost and danger of destruction by fire. Where practicable they are set on heavier grades than ditches, 30 to 35 feet per mile, and are consequently of proportionately smaller area than the ditches. In their construction a straight line is the most desirable. Curves, where required, should be carefully set, so that the flume may discharge its maximum quantity. Many ditches in California have miles of fluming. The annexed sketch will show the ordinary style of construction.

The planking ordinarily used is of heart sugar-pine, 1 to 2 inches thick, and 12 to 18 inches wide. Where the boards join, pine battens, 3 inches wide by 1 thick, cover the seam. Sills, posts, and caps support and strengthen the flume every four feet. The

posts are mortised into the caps and sills. The sills extend about twenty inches beyond the posts, and to them side braces* are nailed to strengthen the structure. This extension of the sill timbers

* Side braces and the extra extension of the sill are, in many cases, only an unnecessary expenditure of money.

affords a place for the accumulation of snow and ice, and in the mountains, such accumulations frequently break them off, and occasionally destroy a flume.

To avoid damage from slides, snow and wind storms, the flumes are set in as close as possible to the bank, and rest wholly or partially on a solid bed, according as the general topography and costs will admit. Stringers running the entire length of the flume are

The details of the cost and construction of this flume are to be found in Raymond's Report, 1875.

placed beneath the sills just outside of the posts. They are not absolutely necessary, but in point of economy are most valuable, as they preserve the timbers. As occasion may demand, the flume is trestled, the main supports being placed every eight feet. The scantling and struts are used in accordance with the requirements of the work.

VOL. VI.-5