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TRANSACTIONS OF THE 



In computing the above mentioned area, it was limited 

 to mineral lands alone, their boundaries having been 

 sufficiently defined for our purpose ; while the valleys, 

 ravines, and the area of land below the coal measures, 

 are excluded. 



To escape all risk of exaggeration, and to allow for 

 vacant, waste, unprofitable or inaccessible ground, we 

 will deduct six thousand seven hundred acres, or up- 

 wards of one-fourth ; and another fourth nearly we will 

 take upon an estimate of produce reduced to three 

 thousand tons per acre. From these data we obtain the 

 following result : eleven thousand acres yielding five 

 thousand tons per acre ; five thousand acres yielding 

 three thousand tons per acre ; six thousand seven hun- 

 dred acres unprofitable. 



The gross amount is seventy millions of tons, which 

 will furnish one hundred and forty thousand tons per 

 annum, during five hundred years, and require the 

 average annual working, to obtain that supply, of about 

 thirty acres. 



The following table represents the comparative specific 

 gravity, cubical contents, weight, and gross produce per 

 acre of the principal varieties of coal, iron, and stone 

 referred to in the foregoing article : — 



