536 MINING INDUSTEY. 



The proportion of first-class, or smelting, ore to the second-class, or stamp- 

 rock, appears from the accounts to be about one in fifty. 



Thus we have in — 



April 8 in 374 or 1 in 46 



May 15 in 445 or 1 in 30 



June 6 in 592 or 1 in 97 



July 4. 5 in 598. 5 or 1 in 133 



August-. 12 in 428 " or 1 in 35f 



Or, for the five months 45.5 in 2,437.5 or 1 in 53.6 



This statement shows that the great bulk of the ore produced by the 

 class of veins represented by the Burroughs is of the low-grade, or stamping 

 rock. The proportion of the two classes above given differs considerably from 

 the general estimate of those who do not keep careful accounts, but, so far as 

 the data furnished by this mine and others, where the relative quantities of 

 the two classes of ore are accurately noted, aiford any basis for judgment, the 

 proportion of first-class to second-class ore is very small. 



The relation existing between the amount of ground mined and the quan- 

 tity of stamp-rock produced is indicated by the following figures : 



Month, 



Fathoms of ground 

 stoped. 



Tons of stamp 

 rock produced. 



Tons per fathom. 



April 



May . . . . , 



June 



July 



August .... 



Or an average of 



46.5 



61. 



71.66 



82.8 

 53. 



366 

 430 



586 



594 

 416 



7.87 

 8.15 

 8.17 

 7.17 

 7.83 



7.60 



The fathom paid for in stoping is the running or superficial fathom ; that 

 is, six feet measured on the length and the dip of the vein, but varying in 

 width according to the thickness of the vein. Estimating the average width 

 of the stope at little more than three feet, the weight of the solid fathom 



