90 CLASSIFICATION OF THE PUBLIC LANDS. 



ments given. In this, of course, the Government is favoring the 

 buyer to the extent that the computed safe average is below the 

 actual average of measurement ; but, on the other hand, it is believed 

 that this is no more than would properly be demanded by the aver- 

 age purchaser of private coal lands who, knowing the measurements 

 of thickness on the land to be purchased, wishes to safeguard himself 

 against the possibility that the measurements will prove to be above 

 the average of all of the coal. This safeguard is, of course, in addi- 

 tion to the allowance for such a possibility in the purchase price. 



VAIitTB PEK ACBB. 



The Government prices for coal land are based on an assumed 

 possible recovery of 1,000 tons per acre-foot. As an acre of coal a 

 foot thick contains 1,750 to 1,800 tons, this recovery represents about 

 60 per cent of the coal in the ground. This percentage was long 

 used in commercial estimates, though at present it is usually much 

 exceeded by the percentage actually recovered in all good coal min- 

 ing, especially in the bituminous fields of western Penn^lvania and 

 in many regions in the Central West where the longwall method of 

 mining has been practiced, by which the recovery in many places is 

 estimated at 90 per cent or more. 



Although a recovery of 1,000 tons per acre-foot is fixed in the regu- 

 lations and is used in all computations, the value per ton assumed for 

 coals thinner than 6 feet or thicker than 10 feet recognizes the re- 

 covery of more than 1,000 tons per acre-foot for coal in thin beds and 

 of less than 1,000 tons per acre-foot for coal in very thick beds, thus 

 avoiding the use of a variable recovery factor in making individual 

 computations. 



If more than one bed underlies a tract of land the early rule in 

 valuing was to take the normal value of the bed likely to be worked 

 first, 60 per cent of the value of the bed next worked, 40 per cent 

 of the value of the next, and 30 per cent of the value of any others, 

 the reduction being made on the beds not worked at first to allow for 

 interest on the investment for the long period during which they re- 

 mained in the ground. Fuller consideration of this subject, how- 

 ever, and closer study of the operation of many mines that work 

 several beds simultaneously or one immediately after the other and 

 of the practical advantages of using the same plant for working beds 

 either simultaneously or successively have led to the belief that these 

 advantages more than outweigh the added interest that accrues dur- 

 ing the longer period of holding. 



Accordingly, under the regulations now in force, consideration is 

 had only of the total quantity of coal in the ground, no reduction 

 being made for interest on the investment if, after allowance for 



