93

a—s

It will be seen from the above statistics that even at an early date, or over eleven years ago, steps were taken to ascertain the value of each portion of the work, and the duty of a sluicehead of water. The French Hill claim averaged about Is. 10^-d. per cubic yard of gravel washed; and the cost of labour and expenses connected with working was 3Jd. The amount of work done with one sluice-head of water was 1-8 cubic yards per hour. The Light claim averaged 3Jd. per cubic yard of gravel washed, and total expenses connected with working were 2 T \d. per cubic yard; while the amount of gravel washed in one hour with one sluice-head of water was 3 cubic yards. The Chesnau claim averaged B|-d. per cubic yard of gravel washed, and the expenses were 2f d. The quantity of gravel washed per sluice-head of water in one hour was 2$ cubic yards. The Sicard claim averaged sf-d. per cubic yard of gravel washed, and the expenses were about 2d. per cubic yard. The quantity of gravel washed per sluice-head of water in one hour was 4'B cubic yards. The Johnson claim averaged 2Jd. per cubic yard of gravel washed, and the expenses ljd. per cubic yard; while the quantity of gravel washed per sluice-head in one hour was 3 cubic yards. The dimensions of the sluices in each of these claims were 4ft. wide and 2fc. Gin. deep. The grade of the sluice-boxes is much less than any yet in use in this colony: for washed gravel-drift, indeed, the miners here would consider such a low grade quite unworkable. Nevertheless, even with this grade, very poor auriferous gravel has been made to pay. These grades are only resorted to when the fall is not sufficient for tailings-room. The lengths and grades of the principal tunnels in the mining district of Smartsville, Yuba County, California, are as follows : —

The length, cost, and grades of the important tunnels in Nevada County are as follows:—■

The North Bloomfield Company is one of the most important hydraulic sluicing companies in Nevada. The ground is too cemented and hard to wash away readily by hydraulic pressure, and therefore they use a large quantity of explosives to shatter the ground before commencing to wash it away. This adds considerably to the expense of working. The value of explosives used in three years amounted to one-third the total value of labour in working the mine, as the following statement of details of work done in the company's claim No. 8 during three years, 1874 to 1877, will show:—

This claim averaged 3f d. per cubic yard of gravel washed during a period of three years, and the expenditure connected with working the claim for same period averaged 2d. per cubic yard ; while the quantity of gravel washed from the bank per sluice-head of water per day was 7 cubic

Name of Tunnel. Locality. Length in Feet. Average Grade, Sabb ... 'actolus lose's Bar ilue Gravel 'ittsburg Slue Point Interprise )eer Creek Timbuctoo Sucker Flat 1,200 1,700 1,600 1,100 900 2,250 1,200 2,200 3ft. 9|in. per 100ft. 4ft. 2 in. 4ft. 2 in. 4ft. 6 in. 4ft. 2 in. 4ft. 2 in. 4ft. 2 in. 3ft. 5 in. Mooney's Flat

Name of Mine or Tunnel. Locality. Length in Feet. Grade per 100ft. Cost of Tunnel. Joston Jorth Bloomfield farrell English imerican lanzanita iweetland Creek $ed-rock Yench Corral Woolsey's Flat ... Humbug Canon ... Columbia Hill Badger's Hill Below San Juan ... Sweetland Sweetland Below Sweetland... French Corral 1,600 9,200 2,200 2,000 5,000 3,500 2,200 4,400 5,048 Ft. 4ir 7 H H £ 8,333 110,000 Not given Not given 33,333 19,167 18,750 15,625 39,583

Year. g il t Is a 'i{ to [So if So e a o +3 | B Grade of Sluico. d qj o3 Ph D o ■i 3 1 | H H I o ital B 3 o :pensei as g ft p 1 ft H Yield. O I I .. .875-76 .876-77 295 342 318 33 52 47 1,858,000 2,919,700 2,293,900 Ft. 180 200 318 i' 6" in 100 4' b" in 100 4' 0"in 100 C. yd. 190 164 153 £ 4,748 8,537 11,196 613 2,142 5,287 627 1,086 1,198 1,180 1,027 2,116 5,223 8,016 4,530 4,535 £ 876 1,534 5,264 11,060 19,750 29,596 £ 15,478 31,153 GO,578 a. 2 3J 6i Averages and totals 955 2,911 44 7,071,600 279 168 24,481 8,042 12,081 7,674 00,412 107,204 31