Note 1 — HENRY S. SIMMONDS.

More than a quarter of a century ago, Professor Buckland when examined before the House of Commons, limits the supply to 400 years. Mr. Bailey in his Survey of Durham limits the supply to 200 years only. But some proprietors when examined in 1830 extended the period of total exhaustion of the mines to 1,727 years; they assumed that there are 837 square miles of coal strata in this field and that only 105 miles had been worked out.

"There were 2936 collieries in Britain in 1860; from these were raised 83,923,273 tons of coal. The greatly increasing consumption of coal has originated fears as to the possibility of the exhaustion of our mineral fuel. It appears that, while in 1820, only 15,000,000 tons were raised, in 1840, the amount had reached 30,000,000, and in 1860, it was nearly 84,000,000. At the same rate of increase the known coal, within a workable distance from the surface, would last at least 100 years. But the consumption, during the last twenty years of the century, would at the present increasing ratio amount to 1464 million tons a year, a quantity vastly greater than can be used. We need not, therefore, now begin to fear lest our coal-fields should be speedily used up."—Chambers's Encyclopedia.