COAL-SUPPLY. Referring to CARBONIFEROUS SYSTEM and COAL for various details connected with the localities of coal-beds, the diversity of qualities, and the modes of working, we shall treat here of a question which has recently been accepted as one of great importance to the welfare of the nation—viz.: the amount of available supply. All the coal now existing was formed untold ages ago, when the conditions of temperature and moisture on the earth's surface were different from those now prevailing. Coal is not a growth annually renewable, but an accumulation which we arc gradually spending. We are living, not on the interest of our coal, but on the capital. This is a truth which scientific men have recognized for some time past; but statesmen and manufacturers, mine-owners and merchants, have paid singularly little attention to the subject, under the supposition that the existing stock will last for so great a period as to relieve us from all anxiety on the matter. John Williams in 1789, sir John Sinclair in the 'Sta tistical Account of Scotland, Robert Bold in 1812, and Dr. Buckland in 1830, were almost the only writers, until recently, who cautioned England that her supply of coal will not last forever. Two volumes on the Coal Question, however, by Mr. Hull and Mr. Jevons respectively, effectually roused public attention to the matter.
At the Newcastle meeting of the British association in 1804, sir W. G. Armstrong, as chairman, forcibly urged the subject on the attention of scientific and practical men. He said: "Contemplating the rate at which we are expending those seams of coal which yield the best qualities of fuel, and can be worked at the least expense, we shall find much cause for. anxiety.. . . . We have already drawn from our choicest mines a far larger quantity of coal than has been raised in all other parts of the world put together; and the time is not remote when we shall have to encounter the disadvantages of increased cost of working, and diminished value of produce." He urged especially that we ought not to squander our coal as at present. We waste nearly all the smoke, heated air, and heated gases from our furnaces; we waste sadly in our open fire-places; and there is a vast quantity of small-coal recklessly burned at the pit's mouth. Various
statistic's as to supply and consumption bad furnished sir W. G. Armstrong with his data. So widely have estimates differed as to available quantity still in store, that between 1792 and recent times, the conjectures, for Northumberland and Durham alone, varied from 200 years to 1700 years, as the period during which the whole nation could be supplied from this one coal-field; but more earnest attempts have been made in late years to arrive at approximate figures. In 1857, M. De Carrel, a Prussian mining-engi neer, estimated the coal-mining of that year in all countries at 125 million tons, with an average value of 7s. per ton at the pit's mouth; he credited Prussia with enough unex hausted coal to supply all the world for 900 years. In 1861, Mr. Robert Hunt ascertained, by reliable mineral statistics, that Great Britain raised 86 million tons in the year; that the quantity was increasing by nearly 3 million tons every year; and that we were work ing our mines at thrice the rate which had been in force 20 years before. These facts had much influence in drawing the attention of public men to the subject. The produce of Great Britain in 1861 was from 3,052 collieries; and the different districts joined in the supply as follows:,Durham and Northumberland, 19 million tons; Lancashire, 12: Yorkshire, 9; Staffordshire and Worcestershire, 7; South Wales, 7; Derbyshire and Nottinghamshire, 5; Scotland, 11; all other' districts, 16—amounting to a total of 86 million tons. M. Burnt, in his Situation de l'Inrlusfrie HoulWre en 1864, estimated the coal-produce of the world at 141 million tons, of which he credited Great Britain with about four-sevenths. In the same year, sir W. G. Armstrong, taking Mr. hull and Mr. Hunt as his authorities. estimated the available stock of coal in the United Kingdom at 80,000 million tons, rejecting all seems below 4,000 ft. as too deep to work. and all less than 2 ft. thick as too thin to work. Taking 1864 as a standard of consumption, it would last 930 years; but at the rate of increase of regent years, it would only last 212 years, because this rate would be geometrical mid not merely arithmetical in its progression.