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414 



SUPPLEMENTARY INVESTIGATIONS IN THE GRAVEL REGION. 





underneath it. The main lava ridge rises to an altitude of about 400 feet higher than the upper 

 bench. 



The water for these mines is brought from the South Yuba River. The Blue Tent Company 

 owns a ditch which, we have already seen, extends above Omega.* The Sailor Flat Company buys 

 from the Blue Tent Company, or from the South Yuba Water Company, which has an office at 

 Nevada City. At Sailor Flat 1,300 inches of water are used per day, under 300 feet pressure. The 

 nozzles are five and six inches in diameter. At the Blue Tent mines the ordinary nozzles are from 

 six and a half to seven or eight inches in diameter. Nozzles of nine inches in diameter have been 



sometimes employed. 



Since the organization of the English company at Blue Tent, careful records have been kept of 

 the amount of water used, the amount of gravel moved, and the yield of gold. Through the 

 kindness of Mr. Hughes I was allowed to take the following data from the company's records : 



(1.) Between Sept. 1, 1876, and Aug. 15, 1877, the gravel removed at the South Yuba claim 

 (Gopher Hill) amounted to 632,533 cubic yards, which was an" average of 5^ cubic yards per 

 twenty-four-hour inch of water. The yield was 12 T G () cents per cubic yard of gravel. 



(2.) For the year 1878, at the same claim, the gravel removed amounted to 501,028 cubic yards, 

 or an average of 6 T J <j- yards per twenty-four-hour inch of water. The yield was 14 cents to the 

 yard. 



(3.) In 1878, at the "Blue Lead," there were removed 235,703 cubic yards of gravel, an 

 average of 5j\% yards per inch of water, which yielded 7 cents per cubic yard. 



(4.) From September, 1876, to August, 1877, there was a very large quantity of top gravel 

 moved at the Enterprise ground. The gravel was fine, loose, and sandy, and easily moved. The 

 amount removed was 1,398,963 cubic yards, at the rate of 10 T y> 7 cubic yards to the inch of water, 

 but the yield was only 2 T § ff cents to the yard, barely sufficient to cover expenses. 



(5.) In 1878, at Gopher Point, a mass of hard, indurated, clayey gravel, which could neither be 

 washed nor blasted with ease, was removed at the rate of only 2/ 8 - cubic yards per daily inch of 

 water. 



From the above figures it will be seen that the average yield has not been quite as much as was 



estimated at the time of the formation of the company. In Raymond's report for the year 1873, 



page 115, it is stated that up to that time there had been removed, according to the surveys of Mr. 



Bradley, 5,101,150 cubic yards of gravel. The yield up to that time was estimated at $770,000, 



equivalent to fully 15 cents per cubic yard, — and that to a large extent from the upper strata of 



the gravel, at some considerable distance from the bed-rock. 



Mr. Hughes's estimate of the probable loss of gold in the hydraulic washings is fifteen per 

 cent. 



I have already t alluded to the difficulty of determining the precise position of the old channel 

 at Blue Tent, and to the hypothesis adopted by Mr. Hughes, and I might have mentioned at the 

 same time another view which is held by some well-informed persons, namely, that the channel 

 extends under and across the ridge to a connection, by way of Scott's Flat, with the enormous 

 deposits of gravel at Quaker Hill and You Bet. I was not able to make any personal examination 

 of the intervening ground, but from what I could learn by inquiry of persons acquainted with 

 the country, and from what I saw at Blue Tent and Quaker Hill, taken in connection with the 

 relative altitudes of the bed-rock at the two places, I feel confident that no such channel exists. 

 That there was, however, once a connection between the Blue Tent gravel and that at Columbia 

 Hill, and, in general, that on the divide between the South and Middle Yubas, cannot be denied. 

 The identity of bed-rock level at Gopher Hill and Grizzly Hill has already been alluded to. There 

 is also a practical identity in the level of the upper surfaces of the gravel on the two sides of the 

 South Yuba. Columbia Hill and Blue Tent are in plain sight of each other with no intervening 



* According to .Raymond's report for 1873, page 115, the "Blue Tent Company brings its water through 274 

 miles of ditch from Culbertson's Bridge on the South Yuba River, 

 t See ante, p. 411. 





