18 AGRICULTURAL SURVEY

A calculation of the quantity of coa! in an acre of ground, ſuppoſing the aggregate thickneſs of the various ſeams a- mount to 6 yards.

An acre of ground contains- 4840 ſquare yards» which multiplied by the thickneſs, 6 yards, gives--=- 29040 cubic yards

in an Acres From which dedudt+ for waſte, and the part or pillars e 9ó80 to be left in working 2

there remains=‘-- 19360, cubic yards to be wrought.

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

Newcaſtle chaldron»

therefore 9260= gives 6453 Newcaſtle chaldrons per divided by 3 acre.

The coals exporied yearly from the rivers Tyne and Wear, with Hartley and Blyth, amount to about 825000 chaldrons,*® which, with the home-conſumption of the two counties of Northumberland and Durham, will make the guantity of coals raiſed yearly about 1,000,000

chaldrons-

And the chaldrons raiſed yearly 1,009,009= gives IS;

divided by the chaldrons per acre 6453(acres near ly per year, cleared of coal 6 yds, thick.

And by eſtimating the breadth occupied by the caking coals to be on an averge 8 miles broad, and 25 miles long, ¡n the two counties, we ſhall find there will be about 200 ſquare miles, or 128000 acres, of coal proper for expor- tation-

* From Newcaſtle, 510000 chaldrons- _—_— Sunderland, 3 I 5000 ditto. In all 825000

Then

R—— R RS 8 2

po fieri A

E ES

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