OLABSIPICATION OF MINEEAL LANDS. 



85 



tons an acre-foot for a 6-foot bed are considered fair recoveries. But 

 1,000 tons of coal at 1 cent a ton is $10, and 1,200 tons at 0.84 cent a 

 ton (84 per cent being the corresponding value of a 6-foot bed) is 

 $10.08. It is then practically immaterial whether land containing a 

 6-foot bed is valued at 84 per cent of the normal value of land con- 

 taining a 10-foot bed of coal of a certain grade and an assumed 

 recovery of 1,200 tons an acre-foot or whether the same value per 

 ton and the same recovery per acre-foot are assumed as with the 

 10-foot bed. As the latter treatment is the simpler it has therefore 



^4 



.2 3 



I- 



25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 IZ5 130 135 

 Mining rate in cents per ton for bituminous coal 



FiGUEB i.- — Rates paid in tlie United States for mining coal of specified thicknesses and 

 curve (A-B) sliowlng average relation between mining rate and thickness. 1, 2, 3, 

 Wyoming, southern fields, run of mine, agreements of 1912. 4, 5, Colorado, north- 

 eastern coal fields, run of mine, agreements of 1912. 6, Montana, Eed Lodge field, run 

 of mine. 7, Indiana, miscellaneous agreements, run of mine. 8, Indiana, block coal 

 agreements, screened. 9, Michigan, summary of agreements of 1910. 10, Missouri, 

 summary of agreements, run of mine. 11, Missouri, Bates and Vernon counties, run of 

 mine, agreements of 1908. 12, West Virginia, summary of agreements, screened. 13, 

 Kentucky-Tennessee, Jellieo mining district, screened. 14, Tennessee, Durham Coal & 

 Iron Co., run of mine. 15, Tennessee, summary of agreements, run of mine. 



been adopted and the value of a ton of any coal in the ground is 

 taken as constant for thicknesses between 6 and 10 feet. 



The rate of increase in cost of mining a bed less than 6 feet thick, 

 however, is too great to be compensated for by the greater recovery 

 per acre- foot. After making various assumptions as to fair average 

 acre- foot recovery for thin coals — assumptions based on known recov- 

 eries — and after computing the value of the coal in thin beds, accord- 



