This means of conveyance is certainly a very practical and inexpensive one; it does away with railroad material, engines, engineers, the consumption of coal, etc., and may be applied over the deepest ravines, where it would almost be an impossibility to build a railroad, unless a bridge were built, at enormous expense and labor. Let us conclude this article by giving the following estimate, in round numbers, of the world’s present annual production of coal. It is taken from various sources, and may be considered approximately correct. Tons. Per cent. Great Britain, 127,016,747 46.4 United States, 50,512,000 18.4 Germany, 45,335,741 16.5 France, 17,400,000 6.4 Belgium, 17,000,000 6.2 Austria and Hungary, 11,000,000 4.0 Russia, 1,200,000 0.5 Spain, 570,000 0.2 Portugal, 18,000 ——— Nova Scotia, 1,051,567 0.4 Australia, 1,000,000 0.4 India, 500,000 0.2 Other countries, 1,000,000 0.4 ————————— ————— 273,704,055 100.0 III. BORINGS AND SHAFTS. HOW COAL MINES ARE DISCOVERED.—OUTCROPPINGS.—SCIENTIFIC RESEARCHES.—HOW A MARBLE QUARRY WAS FOUND.—BORING A WELL, AND WHAT CAME OF IT.—A LOCAL DEBATING SOCIETY.—INTIMATE RELATIONS OF COAL MINES AND THE STEAM ENGINE.—STRIKING OIL.—“DAD’S STRUCK ILE.”—THE UNHAPPY MAIDEN’S FATE.—COAL INSTEAD OF WATER.—THE TOOLS TO BE USED.—A DEEP HOLE.—TERRIBLE ACCIDENT, AND A MINER’S COOLNESS.—SINKING SHAFTS.—AN INGENIOUS APPARATUS.—ACCIDENTS IN SHAFTS.—REQUIREMENTS OF THE LAW. Until the beginning of the present century coal mines were discovered more by accident than in any other way. The coal seams make their appearance at the surface, that is, they “crop out,” or “come to grass,” as the miners say. Coal on the surface is generally of a poor character, for the reason that it has been for many hundreds of years subject to the action of the elements; but on digging down a few feet, or a few dozen feet, the quality is found to be greatly improved. When coal is thus found at the surface, a preliminary examination is conducted by cutting trenches, galleries, and pits, and if the conditions are favorable, the actual working of the mine can begin. Sometimes the mine is operated by a few cuttings, like the works of an ordinary stone quarry. [Sidenote: DISCOVERING COAL MINES.]