Note 31 — PART II. (continued 2)
Reading edition
To give an idea how long there is a probability of Great Britain being applied with coal from the rivers Tyne and Wear only, it must be observed,
1st. That the Seams of coal which are now worked at Newcastle and Sunderland, are equal to a seam or bed of 15 miles by 20 miles.
2dly. That this seam, on an average, is at least four feet and a half thick.
3dly, That 1-6th part of the above extent is sufficient for pillars to support the roofs of the mines, &c.
And, 4thly, It appears, by experiments, that a cubic yard of coal weighs 1 ton, or 20 cwt.
London Chaldrons
The total consumption of coal from the rivers Tyne and Wear known from the register to be 2,300,000
The number of tons in the above quantity taking the London chaldron at 27 cwt. is 3,100,000
Now a ton weight of coal is estimated to occupy in the earth the space of one cubic yard.
The number of cubic yards in the square mile is 3,097,600
The beds or seams of coal are, on an average, 4 feet and a half in thickness, which increases the above number of cubic yards in the square mile by half the number of square yards to 1,548,800
And hence the square mile of the beds or seams of coal we are describing contains, of cubic yards and tons of coal 4,645,000
A deduction of 1-6th for pillars to support the mine, &c. 800,000
The number of tons per square mile 5,445,000
We have already mentioned the length and breadth of the seams of coal to be equal to 20 miles by 15, making an area of 300 square miles, and consequently a source of consumption for 375 years.