[478] 



A TABLE, 



FOR CALCULATING THE WEIGHT AND YIELD, PER RUNNING 

 FATHOM, OF MINERAL VEINS. 



By B. J. CHAPMAN, Ph.D., 



PROFESSOR OF MI^faEALOGY AND GEOLOGY IN UNIVERSITY COLLEGE, TORONTO ; AND CONSULTING 



MINING ENGINEER. 



The weight in tons and average richness of mineral veins are usually 

 given per running fathom : that is, per parallelogram measuring six 

 feet in length, and six feet in depth, by the mean width of the vein, 

 whatever the latter may be. The following table will enable these 

 results to be calculated very rapidly, provided the specific gravity of 

 the veio matter (mixed ore and gangue), and the average per-centage 

 of metal or mineral carried by the vein, be previously ascertained. 

 The table has been calculated on the supposition that the sp. gr. equals 

 unity, and that the average yield in metal is equivalent to one per cent. 

 The values given in columns ill. and iv. must thus be multiplied by 

 the sp. gr. of the vein matter ; and those given in column v. must be 

 multiplied also by this quantity, and the resulting product must finally 

 be multiplied by the average per-centage of metal or mineral as ascer- 

 tained by estimate or by actual assay. The values in column v. corres- 

 pond to both the British ton of 2,240 lbs., and the American ton 

 (chiefly used in Canada) of 2,000 lbs. Where the width of the vein 

 is in feet and inches, the values of the two, as given in the table, must 

 of course be added together. 



Example. — A vein averages 3 feet in width, with sp. gr. equal to 

 3-8, and per-centage of metal equal to 2-6. Required the weight in 

 British and American tons, and the yield (exclusive of loss in mechani- 

 cal and furnace treatment) per running fathom. 



3 tons (see the Table) X 3 '8 — 11^- British tons (nearly). 

 3-36 tons (see the Table) X 3-8 = 12| American tons. 

 67-30 lbs. (see the Table) X 3-8 X 2-6 = 665 lbs. 



Each fathom, therefore, of a vein of this strength, will contain 108 



