3ia 



July 



In this (haft, there are fifteen feams of coal, of which only four 

 are workable J viz. 4th, 7th, nth, and 12th, rnaking together 

 4 yds* I ft. 7 in. c ^ workable coa]. If the medium be taken be- 

 twixt this and St Anthonys, it ^^ill be nearly 6 yards thick of 

 workable coal, from which may be formed, 



./i Calculation of the quantity of coal in an acre of ground ^fuppofng 

 the aggregate thicknefi of the various feams amount to fix yards. 



An acre of ground contains - 4840 fquare yards j 



which, multiplied by the thicknefs, 6 yards, 



gives . - - 29,049 cubic yards in 



an acre. 



From which dedudl one third for waile, 

 and the part or pillars neceffary to be 

 left in working, - - 9680 



there remains - - 19,360 cubic yards to 



be wrought. 

 And, as three cubic yards of coal, when wrought, affords a 

 Newcaftle chaldron, 

 therefore 10,360 



gives 6,453 Newcaftle chaldrons per ac^e 



¥ 



divided by 



The 



