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204 



THE AUEIFEKOUS GRAVELS OF THE SIEERA NEVADA, 



Humbug Creek, a short distance from the South Yuba River, and follows 

 nearly the course of the canon, some 200 feet below its bed. This tunnel, 

 which is 7,874 feet in length, has a grade of four and a half feet in a hundred, 

 and is eight feet by eight in dimensions above shaft No. 6. Its total cost is 

 stated at half a million of dollars. Other tunnels in this region are : the 

 Boston, leading to Woolsey's Flat, length 1,600 feet, and cost $ 40,000 ; Far- 

 rell, to Columbia Hill, length 2,200 feet ; English to Badger Hill, length 1,400 

 feet; American, below San Juan, 3,900 feet long, cost about $140,000; 



Manzanita to Sweetland, length 1,740, cost $ 



also to Sweetland gravel, length 



2,200 feet, cost $ 



Sweetland Creek, 

 0,000; Bed-Rock, 



of Messrs. Hague 



below Sweetland, length 2,600 feet; French Corral, length 3,500 feet, cost 



$ 165,000.* 



The fact that most of the gravel between the Middle and South Yuba riv- 

 ers belongs to large companies renders it probable that we shall eventually 

 obtain from this region much fuller and more accurate statistics than it has 

 been possible to procure from other parts of the hydraulic mining region ; 

 where, usually, as will have been recognized from an examination of the 

 preceding pages, trustworthy information on most of the important points 

 can hardly ever be obtained. Some data of this kind are already 

 at hand, and have been published in the papers 

 and Bowie, which have already been cited several times. The investi- 

 gations made at the North Bloomfield Company's works quite harmonize 

 with the general result already made evident in the preceding pages of this 

 volume, that the particles of gold are in most cases scattered through the 

 whole body of the gravel ; but that they are more numerous and of larger 

 size in the lower portions of the channel, and especially immediately over and 

 on the bed-rock surface. The results obtained by Professor Pettee,t in re- 

 gard to the small yield of the top-gravel near Gold Run, are quite similar to 

 those published by Mr. II. Smith, Jr., the able Engineer of the North Bloom- 

 field Gravel Mining Company, of the amount obtained from the upper por- 

 tions of their deposit. It appears from his statement, X that this company in 





* Mr. Skidmore, in the Sixth Beport of the Commissioner of Mining Statistics, states that the cost of the. 

 improvements made by three of the principal mining companies in this district, the " North Bloomheld 

 Gravel Mining Company," the "Union Gravel Mining Company" and the " Milton Mining and Water 

 Company," had np to 1874 amounted to $3,500,000 ; and that nearly % 1,000,000 more would he required 

 to complete the works then in progress, so as to fully open up the gravel deposits belonging to these 



var i ou s com pan i es. 

 f See ante, p. 152. 

 % Quoted by Mr. Bowie in his paper previously referred to. 







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