THE GRAVEL: NEAE SMAETSVILLE AND T1MBUCT00. 



19° 



tailings were often rewashed, with greater profit than that obtained from the original washing, and 

 the operation has in some cases been repeated several times on the same material* The improved 

 sluices differ from those formerly in use principally in being much longer and less steep. 



Both " rock bottom " and " block bottom " sluices are in use in this district. When quarried 

 rock is used, it is laid in the box with a thickness of from fifteen to eighteen inches. Boulders, 

 selected from the coarse gravel as it comes from the bank are also used, and it is said that one 

 man can lay eight boxes a day (ninety-six feet) with stone fifteen inches deep, the width of the 

 box being not less than three, nor more than four, feet. When wood is preferred at Smartsville, 

 that of the " digger pine " (P. Sabiniana) is taken, and the blocks are cut seven inches thick. 

 They are set with the fibres of the wood vertical, and can be turned and used on the other side, when 

 the first surface gets too rough. A " run " with wooden blocks lasts from twenty to thirty days ; 

 at the end of that time the bottom gets so uneven that a " clean-up " and repairs are necessary. 

 With a rock bottom, on the other hand, no change need be made for 100 or 150 days. 



In regard to the yield of the gravel in the Timbuctoo and Smartsville district, Mr. Pettee was 

 not able to procure any information upon which an average per cubic yard could be obtained. 

 From all that could be learned, it appeared that the yield of the gravel varied so much at different 

 times and in different places that nothing like a fair and trustworthy average was obtainable. And 

 a similar remark may be made with reference to the total production of the mines as a whole or 

 individually. The most satisfactory item obtained was this: That the Blue Gravel Company's 

 ground had been worked since 1864 with great success, over a million of dollars having been taken 

 out, with a supposed expenditure of thirty-five per cent of the yield ; but whether this included the 

 cost of the expensive bed-rock tunnel was not ascertained. The gross yield of the Smartsville Con- 

 solidated Company was given at $225,000 per year, with an expenditure of sixty per cent of the 

 yield. A few items may bo added in regard to the use of powder, in this district, for loosening 

 the gravel as a preliminary for sluicing it. There are two principal methods in use. One is, to 

 mn a drift near the bottom of the bank for a distance of twenty or thirty feet, and then side drifts 

 of sufficient length to insure the throwing out of the whole bottom front, after which the upper 

 Portion must fail of its own weight, or when subjected to the action of the water. The other 

 method is to run in a drift to a distance of 100 or 200 feet and then excavate side chambers and 

 Side drifts to such an extent that a large quantity of powder can be exploded at once (by elec- 

 tricity), so far from the surface that none of the gravel will be thrown to any considerable distance, 

 out the whole mass shattered. From 200 to 450 kegs (each keg weighing twenty-five pounds) of 

 powder are commonly used in a moderate blast ; but sometimes much larger quantities are em- 

 ployed. In the spring of 1870 the Smartsville Consolidated Company set off a blast of 1,500 

 kegs. 



As to the loss of gold in the operations carried on in the Smartsville district, the information 

 ich could bo obtained was, as everywhere else, exceedingly vague, there being no means of deter- 

 mining it accurately. It was the opinion of some well-informed miners that not over twenty per 

 cent was lost, while others set the amount as high as fifty per cent, and expressed the opinion that 

 e bars of the Yuba, into which the tailings are run, would be found to be as well worth working 

 as they were in 1849. 



_^ In regard to the quality of the gold obtained in this district, and its position in the gravel, Mr. 



e tee obtained the following information. The fineness of the gold is such that its value ranges 



rom $ 17.50 to f 19.25 per ounce. Mr. Ackley's statement of the returns of the fineness of the 



964 ^ fr ° m tllC Snmrtsvill ° Consolidated were in four cases, respectively, .919 to .936; .919 to 



obt * * 917 t0 " 9G1 ' " 918 t0 i98 *" TIl ° hi S ncst % ures in the I*"* three cases belong to gold 

 ained from the distillation of the mercury which passed through the meshes of the strainer, 



ln »g the straining of the amalgam. This seems to contain the smallest and purest grains of all, 

 a M pays for a separate distillation. 





I 





In one case this gold ran as high as .976. 



The average nne- 



* This is called 'Mail-sluicing." 



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