Heinrich Ries and others

“ Thus the freedom of burning increases with the amount of volatile hydrocarbons, while the heating power depends on the amount of fixed carbon present. Sulphur is an injurious constituent when the coal is to be used in the manufacture of gas or for metallurgical purposes; while ash is undesirable, since it displaces so much carbon, and if it contains fusible impurities such as iron, lime, or alkalies, it causes clinkering. Moisture retards the heating power of the coal until it is driven off. ”

“ Cannel Coal is a variety of coal very rich in volatile hydrocarbons, and found sparingly in parts of Kentucky, Ohio, and Indiana. Its chief use is as a gas-enricher, since it yields 8000 to 15,000 cubic feet of gas per ton. Cannel coal is so called because it burns with a bright flame like a candle, and the name parrot coal was given to it in Scotland, from the crackling or chattering noise it makes while burning. ”

“ The coals are all bituminous or semi-bituminous with the exception of those at the northeastern end, in Pennsylvania, where close folding of the rocks has changed the bituminous into anthracite coal. In general, the rocks at the upper or northern end of the Appalachian belt are folded, while those of the lower end, as in Alabama, are often faulted in addition, so that the coal-miner frequently finds the coal-seam suddenly broken off. ”

“ In 1822 the amount of coal mined in Virginia was about 48,000 long tons. Now the production for the United States is about 270,000,000 short tons, or greater than that of any other country of the world.
Coal is used largely for domestic purposes, either as fuel or, in the form of gas, for illumination. Its use for the latter purpose is, however, not so widespread as formerly, water-gas having superseded it to a considerable extent. In the production of steam for motive power it also finds important applications. ”

“ 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. In 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 × 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. ”

“ 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, amounting in 1900 to 51,638,000 short tons, valued at $193,032,000. 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. ”

“ 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.
COAL-MINING ”

“ 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. ”

“ 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 coal-fields of the last-named country are probably the greatest in the world, and may become a source of European supply. Up to the present time they have not been developed in a systematic manner. Italy, Spain, Sweden, Australia, New Zealand, Borneo, the Philippine Islands, and many countries in Africa also produce coal; while in America deposits are worked in Canada, Mexico, Chile, and Argentina, and are known to occur in Colombia and Peru.
United States. The coal-fields of the United States are especially extensive ”

“ 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 ”

“ 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. ”

“ 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 preparation of mined coal for the market consists in screening the coal over bars and through revolving or over shaking screens, together with breaking it with rolls to produce the required market size. ”

“ 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 use—hoisting 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 special counter-balance assists the engine to hoist the loaded ascending cage. ”

“ 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. ”

“ 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. ”

“ 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 steaming, coking, and house coals are produced. ”

“ These coals are all bituminous, of Carboniferous age, and are used chiefly for steaming. The thickness of the Carboniferous System varies from 1200 to 1400 feet in southern Illinois, to about 600 feet in Indiana, and the workable coal-seams vary in number from 7 to 12 in Illinois, and their thickness from three to eight feet. The ‘block coal’ of Indiana has quite a reputation. The Western Central area includes Iowa, Missouri, Arkansas, Indian Territory, Kansas, and part of Texas. ”