COAL. Crested Butte have been changed locally to anthracite by the metamorphic action of igneous intrusions. Excellent coking coals are found near Trinidad. The New Mexican coals are in part an extension of the Colorado veins, and bear a good reputation, as do also many of the Wyoming coals. California has little fuel of good quality, and has for many years drawn on Australia for its coal-supply, but in recent years the coals of Oregon, Washington, and British Columbia have become a source of supply. The rocks of the small Rhode Island area have been so highly metamorphosed that the coal has been altered to graphitic anthracite. It is sold on the market as amorphous graphite, and has little value as a fuel. CANADA. The Acadian field includes deposits in Nova Scotia and New Brunswick, the former being quite important. The coals are bituminous and of good quality. In the mountain ranges of British Columbia extensive coal-seams have been discovered, and they are now under development. A good quality of coke is made from the coal of Crow's Nest Pass, which finds a market at the British Columbian smelters. The most productive mines of the Pacific Coast are located on Vancouver Island, whence large shipments of bituminous coal are made to San Francisco and other ports in the Western United States. SOUTH AMERICA. Coal, probably of Carboniferous age, is found in the Brazilian States of São Pedro, Rio Grande do Sul, Santa Catharina, also in the neighboring Republic of Uruguay. Very little development work has been done in the fields, and the output is inconsiderable. In Argentina and Chile, where Cretaceous coal occurs, there is more activity; but these countries still depend largely upon Great Britain for their supplies. In Peru both Cretaceous and Carboniferous deposits are found at various points in the interior, the former occupying a position on the first rise of the Andes, while the latter occurs in higher ground and at a greater distance from the coast. UNITED KINGDOM. Next to the coal-fields of the United States, those of the United Kingdom are of the greatest economic importance. With in the limits of England, Scotland, and Wales there are more than twenty areas underlain by seams of anthracite, bituminous, and cannel coal. The largest of these areas is that of South Wales, in Monmouthshire and Pembrokeshire, which has a length of about 50 miles and a width of nearly 20 miles. The coal-measures form an elliptical basin, and are several thousand feet in thickness. Coal is found in three horizons, of which the upper has no less than 82 seams, measuring 180 feet in all. The lowest horizon yields valuable steam and blast-furnace coal. In the north of England the coal-fields of Lancashire, Derbyshire, and Yorkshire are the largest. The Lancashire field is of irregular quadrilateral form, with a width of about 18 miles from north to south, and a length from east to west of more than 50 miles. It includes about 100 feet of coal in workable seams, which dip at a high angle and are much broken by faulting. The Yorkshire and Derbyshire measures occupy a single area that extends for a distance of about 60 miles from Bradford on the north to near Derby on the south, and has a breadth of from 3 to 32 miles. They yield bituminous coal, excellent for steaming and iron-making purposes. North of the Yorkshire field is the large basin of Northumberland and Durham, from which steam. ing, coking, and house coals are produced. In Scotland the coal-measures are extensively developed in Ayrshire, Lanarkshire, Stirlingshire, and Fifeshire. The productive coal-fields of the United Kingdom belong to the Carboniferous period; brown coal of Jurassic or Tertiary age is known to occur, but the seams are too small to be profitably exploited. The exports of coal from this country are of great importance. Much of the coal goes to Italy, Russia, Holland, and to the European countries that possess small resources of the mineral, while the remainder is exported to the more remote parts of the world. Further details regarding the distribution of coal will be found under the titles of countries. OUTPUT. The world's annual production at the present time is about 1,000,000,000 short tons; the output in 1900, or the latest year for which statistics are available, according to The Mineral Resources, was distributed as follows: It is interesting to follow the progress of the United States as a coal-producer. In 1868 Great Britain produced 3.6 times as much coal as the United States, while Germany's product that year was 15 per cent. greater than that of the United States. In 1871 the United States exceeded Germany's output by about 10 per cent., but afterwards fell back to third place until in 1877 she once more sprang forward, and gained on both Germany and Great Britain. In 1899 the United States led the world, and in 1904 supplied 36 per cent. of its production. The larger part of the increase during recent years has been due to the great expansion in the mining of bituminous coal. The output of anthracite in 1904 amounted to 73,156,709 short tons, showing a gain since 1880 of 44,506,897 tons, or 155 per cent. In the same year the production of bituminous coal was 279,153,718 short tons, an increase of 236,321,960 tons or 552 per cent. This feature will, doubtless, be more accentuated in the future than in the past owing to the wide distribution and industrial use of the bituminous variety. The production in 1904 represented about 4.24 tons per capita of population and was almost entirely consumed within the United States. There has been recently considerable discussion in regard to the possible exhaustion of the anthracite coal beds in the United States. The opinion is that, in spite of the large consumption and the small area containing anthracite coal, there is no immediate danger of exhaustion. MINING OF COAL. The presence of coal in paying quantities having been determined by prospecting and geological surveys, the next consideration is to extract this coal from seams. No definite rules can be given for the selection of a method of mining that will cover all conditions; each mine furnishes a distinct and separate problem. Every system of mining, however, aims to extract the maximum amount of the deposit in the best marketable shape and at a minimum cost and danger. Speaking broadly, all methods of mining come under the head of either open working or closed working. Open working is employed when the deposits have no overburden of barren rock or earth, or where this overburden is of such small depth that it can be easily and cheaply removed, leaving the coal deposit exposed. The mining of such exposed seams of coal is really a process of excavation or quarrying, and the machines used in making open-pit excavations and in quarrying are applicable to the work. Closed working is adopted when the depth of the overburden is so great that the mining must be conducted underground. The first task in opening up underground coal-seams is to secure access to the seam by means of shafts, slopes, or tunnels. Shafts are vertical openings from the ground surface to the coal-seams. In the United States shafts are usually made square or rectangular in form. This practice is largely due to the fact that timber is used for lining shafts. In Europe round or oval shafts are frequently employed with linings of brick, iron, or masonry. In Generally the shafts are divided into two or more compartments, in each of which is installed an elevator for hoisting the coal-cars to the surface. The number of compartments in a shaft and their arrangements depend upon the particular use to which the shaft is to be put, the number of shafts employed, and their depths. Where the seams are comparatively near the surface, it is usually cheaper to sink a number of two or three compartment shafts than it is to haul all the ore to one large shaft; while, when the shafts are very deep, it is preferable to sink a smaller number of four or six compartment shafts and extend the underground haulage to a single shaft over a great area of the workings. Where timber lining is employed, a stronger construction is obtained by placing the compartments side by side in a long, narrow shaft than by grouping them in a square shaft. shallow mines separate shafts are often employed for hoisting and for pumping, ventilation and ladder-ways. One of the largest coal-mine shafts in America is situated at Wilkesbarre, Pa.; it is 1039 feet deep, 12 X 52 feet in size, and has five compartments. The methods of sinking mine shafts are essentially the same as those used in sinking shafts for tunnels. (See TUNNEL.) Slopes are openings begun at the outcrop of an inclined seam, which they follow down into the earth. Slopes are usually made with three compartments side by side, two of which are used as hoistways and the third for the traveling-way, piping, etc. When the dip of the slope is under 40 degrees the slope is made about seven feet high, but when the dip exceeds 40 degrees cages have to be used and a great height is necessary. Slopes are usually lined with timber. Tunnels are nearly horizontai passageways beginning on the side of a hill or mountain and extending into the earth until they meet the coal-seam; they are built for both haulage and drainage purposes, and are constructed like railway tunnels, except that the cross-section is usually much smaller, and that it is lined with timber instead of with per manent masonry. The forms of timbering used in coal-mining are various, and are of interest chiefly to the practical miner; special treatises should be consulted by those interested in the details. In a general way, it may be said that timber used for underground support in mines should be of a light and elastic variety of wood. Oak, beech, and similar woods are heavy and have great strength, but when they do break it is suddenly and without warning, thus bringing disaster to the miners who might escape if a tough wood were employed which gives warning of rupture by bending and cracking. It is a very common practice to employ preserved timber in mining work. See FORESTRY. The systems of working the coal-seams after access is attained to them by the means described are two, known as the room-and-pillar and the long-wall systems. The room-and-pillar method-also known as the pillar-and-chamber or board-and-pillar method, which may include the pillar - and - stall system-is the oldest of the systems, and the one very generally used in the United States. By this system, coal is first mined from a number of comparatively small places, called rooms, chambers, stalls, boards, etc., which are driven either square from or at an angle to the haulageway. Pillars are left to support the roof. In the long-wall method the whole face of the coal-seam is taken out, leaving no coal behind, and the roof is allowed to settle behind as the excavation progresses, care being taken to preserve haulageways through the falling material. Both the room-and-pillar and the long-wall methods are employed in various modifications, for the details of which special treatises on coal-mines should be consulted. The coal is cut from the seam by hand or by some form of coal-cutting machine. In America machine cutting is used extensively. There are four general types of machines in general use: Pick machines, chain-cutter machines, cutter-bar machines, and long-wall machines; the machines most used in America are pick machines and chain-cutter machines. Both compressed air and electricity are used for operating coal-cutting machines. Pick machines are very similar to a rock drill; chain - cutter machines consist of a low metal bed frame upon which is mounted a motor that rotates a chain to which suitable cutting teeth are attached. The ventilation of the workings, owing to the presence of gases, is a very important feature of coal-mining, and great care is taken to lay out the workings so as to facilitate ventilation. Mechanical ventilation by means of fans and blowers (see BLOWING MACHINES) is usually employed. Hoisting in mines is accomplished by means of cages running up and down the shafts, and operated by large hoisting engines on the surface. There are two general systems of hoisting in usehoisting without attempt to balance the load, in which the cage and its load are hoisted by the engine and lowered by gravity, and hoisting in balance, in which the descending cage or a spe |