We cannot make even an approximate estimate of their value to our resources; figures would scarcely convey an idea. We may calculate the production per acre, and jump at some conclusion concerning the amount per square mile ; but the value of a ton of coal in the mountain, or the same amount in market, has no relation to its dynamic value in the pro duction of mechanical force or motion, its necessity to our manufactures, its importance to the arts and sciences, or indirectly as a means of power and strength in peace or war. Yet its marketable value is no small item in our trade-lists, though comparatively of late development. Its growth or increase is unparalleled by any trade, except the oil trade of Western Pennsylvania; and the rapidly increasing demand for this class of fuel insures a permanent expansion of the trade, equal, perhaps, to the means of supply.
Though the area be small and insignificant, when compared on the map with the wide extent of our bituminous fields, the supply is practically unlimited for all present purposes. A coal-seam five feet thick will pro duce 5000 tons of marketable coal, even under the present wasteful mode of mining. There can be no doubt of an average of 60 feet vertical thick ness of available coal under the entire coal area of the anthracite fields. This would yield 60,000 tons per acre, or 18,000,000,000 in the 300,000 acres which they contain. But under a more careful system of mining, as practised in England and elsewhere, and which will be practised here when coal and coal lands are appreciated at their proper value, one-third more coal may be obtained from an acre of land than is given in the foregoing estimate. The amount of hard anthracite coal existing in an acre of land, as a maximum, is 1613 tons per foot of vertical thickness, or 96,780 tons per acre, according to the 'average estimate of 60 feet total vertical thick ness. In the best English mines, from to of the coal is left or wasted in the pillars. Under the same system of mining, we might obtain nearly 90,000 tons of coal to the acre, or one-third more than our present system will admit of. But we can scarcely hope for the same degree of economy in operating our large veins.
The natural increase of the anthracite coal-trade is about 21 per cent. per annum; and we may anticipate even a larger increase on the pacification of the country, when an impetus will be given to our manufacturing interests far greater than that given by the war, under the protection of fostering tariffs and through the means of our vastly increased capital.
Our present production is 10,000,000 of tons per annum, and in all probability it will not be less than 15,000,000 in 1870. At this rate of increase we may live to see the day when our coal-trade will be 30,000,000 tons annually, and perhaps some of us may be able to count double that amount. But an annual drain of 30,000,000 from our limited area will exhaust the anthracite coal-fields in 600 years,—a small period in the life time of a nation, and but little over our past existence. When compared
with the years of England, France, or China, we find it a short time.
The amount we name is moderate as an estimate, and twenty years may not elapse before its realization. But our estimate does not cover the whole consumption by perhaps half the drain on our resources of anthracite. We may state, without exaggeration, that the drain or actual loss on the original supply since the commencement of the trade has not been less than 189,000,000 tons, or one-half more than the shipments of marketable coal; while our present production of 10,000,000 may be more fairly represented in the actual drain on our resources by 15,000,000 tons shipped, wasted, and lost.
The estimate is that one-third of the coal is left in the mine as inacces sible, lost in pillars, &c. The waste caused by our present mode of crush ing through the "breaker" ranges from 15 to 20 per cent., and sometimes, under certain circumstances, it has exceeded 30 per cent.; and, in addition to these two great items in the waste of our mines, we may mention the home and colliery consumption, which is, perhaps, from 5 to 10 per cent.
In order, therefore, to produce 30,000,000 annually, the drain on our mines or resources would be 45,000,000 under our present wasteful system of mining, since the loss in pillars, waste in fine, and colliery and home consumption, is not less than 53 per cent. of the whole production.
Should the anthracite trade ever approach the proportion of the English coal-trade, our supply would melt away in 180 years. It is not probable that such proportions will ever be assumed by this trade, in view of the vast extent of bituminous coal held in reserve, and the use of unlimited supplies of petroleum, which will usurp the place of the purest carbons in many instances. There are facts, however, in this connection, which justify us in assuming a large demand on the anthracite trade. The anthracite basins are the only large bodies of available coal east of the Alleghanies excepting the small but valuable Broad Top coal, and a few other scatter ing semi-bituminous patches—accessible to the Eastern markets. It is not at all probable that our Western bituminous coal will ever take the place of a superior article for all ordinary purposes: therefore the great source of supply for the East will be in the anthracite coal-fields. The six New England States, New York, New Jersey, part of Pennsylvania, and a large extent of the South on the Atlantic board, must draw the chief portion of their supplies of fuel from thence. The area to be supplied with anthracite is, perhaps, not less than 300,000 square miles, and the present population 12,000,000. This is exclusive of a large trade which finds its way northwest to the great lakes and to Canada, —a trade con stantly on the increase.