Two new hoisting ropes.

Pit-top repaired.

Leoven, Joseph...

COAL.

The origin of coal is no longer a debatable subject, as it is now universally held by men of science that beds of coal have been formed from the decomposition of vegetable matter- the leaves and stems of ancient plants and trees, that grew, died, decomposed and became mineralized on the spots now occupied by coal-beds; and that the associated beds of rocky strata have been formed from the sediment of the water which flowed over the carbonaceous accumulations during the subsidence of the land.

Although coal is found in several parts of the world associated with the rock of different periods, yet practically, it may be considered as existing only with those formed in the carbon period, so called on account of the occurrence of abundant coal deposits; for in no other period are the deposits of sufficient extent or of the required quality to be commercially valuable. Hence, searching for coal in any other formation is a labor holding out but faint hope of reward. The associated rocks known in connection and as the coal measures, consist of a series of beds of sandstone, shale, limestone, fire clay, iron-stone and coal in manifold alternations. In most cases a bed of clay lies immediately beneath and a bed of shale immediately above a seam of coal; that which lies beneath is known as the under-clay or seat of the coal seam, and generally consists of a more dense and plastic clay than that which lies above the seam and forms its top or roof.

The under-clay formed the soil upon which the plants grew, and from which, ultimately, the coal was formed, and, as might reasonably be expected, contains numerous traces of the roots of such plants. It is remarkable that nothing but the roots of the plants are found in the under-clay, and traces of the same consist of dark, carbonaceous, fibrous-looking streaks traversing the mass in all directions. As the under clay originally formed the soil upon which the coal-plant grew, we might expect it found everywhere and invariably present with the coal. As a matter of fact, this is so as a rule, but there are exceptions though of rare occurrence, where the under-clay is absent, and in such cases it may be inferred that the materials from which the coal was formed were drifted in their present location. The existence of the under-clay greatly facilitates the extraction of the coal. The slate which forms the roof is of a more indurated character than that of the bottom, its structure being that of a true shale. It is more frequently absent

than the under-clay, and its absence is detrimental to the economic and satisfactory working of the coal.

Indeed, there can be no doubt that coal seams are the remains of a former mass of luxuriant vegetation of submerged pine-forests, jungle-growth and peat mosses. Deriving its origin from such source, coal-seams must of necessity vary greatly in thickness, since the vegetation of one age or one place would differ widely, in luxuriance and length of existence, from that of another age or place. And as a matter of fact, we find coal-seams varying from one inch to forty feet and upward, in thickness.

MISSOURI.

The coal measures of Missouri cover all that portion of the State lying north of the Missouri river and embracing the following counties in the west and southwest part of the State, and south of the river: Barton, Bates, Cass, Cedar, Cooper, Dade, Henry, Jackson, Lafayette, Pettis, Saline, St. Clair and Vernon. It must be remembered, however, that the coal measures are not supposed to be entirely underlaid with coal, as sometimes even a four-foot seam of coal will suddenly dwindle down to a mere trace, and often cut away entirely. The coal measures proper are supposed to enter the State about the northwest corner of Jasper county and to pass through the State diagonally to Schuyler county. Geologists claim the coal measures of the State comprise an area of 23,000 square miles. The thickness of the upper coal measure, it is claimed, is 1317 feet, including only about four feet of coal, of which there are two seams of one foot each, the remainder being mere streaks. The middle coal measure is about 324 feet thick, embracing seven feet of coal, with two workable veins of 21 and 24 inches respectively, one of 12 inches, and the other six veins too thin to work. The lower coal measures are from 250 to 300 feet in thickness, in which are found five workable veins, varying from 1 to 5 feet in thickness; the remaining seams vary from small streaks to 11 inches, making a total of 13 feet of coal. From this it will be seen that the coal measures of Missouri reach nearly 1900 feet in thickness, with a total aggregate of 24 feet 6 inches of coal. Over so large an area of coalbearing rock, it is but reasonable to expect that future developments will reveal regions containing coal of much greater thickness and value than at present experienced. The coal measures embrace sixty counties, but mining for the past year was prosecuted in only thirty-four counties, and in some of these the product was very small.

MODES OF WORKING.

There are but two systems proper for working the coal of this State-namely, the long-wall and room and pillar plans, or a modification of either. The long-wall system consists in the working off of the entire coal face, and the space in the mine thus left being filled up by its refuse material. To provide for and protect the roadways under this system, pack walls are built along the side, requiring care and skill to be exercised in their construction. If these walls are not well built, or if they be constructed of material of a soft and friable character, the weight of the overlying rocks during the subsidence of the strata will crush and squeeze, thereby entailing much expense in keeping up the roadways. The long-wall method is followed where the conditions are favorable; the thinner the vein of coal and the more refuse it makes (speaking in general terms), the better it is adapted to this system of mining. This system is followed altogether in the counties of Audrain, Caldwell, Clay, Grundy, Jackson, Lafayette and Ray, and also in some of the mines of Henry, Linn, Macon and Randolph counties. But of all the above-named counties, the mines of Lafayette and Ray are the best adapted to the system; here the coal seam is underlaid by fireclay, so suitable for under-mining, and overlaid by a good cap rock, with a foot of black slate coming down with the coal, and which slate furnishes excellent material for building walls along the roadways to support the roof. It was in the mines of the latter counties where the much-improved system of the movable face track was first introduced, and we believe that the credit for the same beiongs to Mr. John Gibson, Supt. of the Richmond Coal Co. This movable face track is being generally adopted at all long-wall mines where it can be profitably used. The advantages of the long-wall over any method of working by room and pillar consists in the ability to work out the entire coal seam, the simplified and easy manner of extracting the same, and the opportunity offered for providing and maintaining ventilation around the entire works. When mines are deep, and the coal is reached only by a great outlay of money in sinking, this system of mining, even though it may cost more per ton than by the room and pillar plan, will save money to the operator in the end, by the greater yield of coal to the acre; in fact, there is no other system of mining by which a thin seam of coal can be worked profitably.

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ROOM AND PILLAR METHOD.

The room and pillar system contemplates the driving of narrow entries, end ways and crossways, in the coal, in advance, by which square blocks of coal are formed. Rooms are then opened only in the cross-entries, with a pillar of coal left standing between each room for the support of the roof; this method furnishes rooms or places for the employment of a large number of miners. The deeper the mine is opened from the surface and the thicker the cover over the coal, the greater is the crushing weight to which the pillars are exposed. Leaving large pillars in the mine entails additional expense in advancing the work, for the reason that the narrow work of entry driving is in all cases paid for extra, and the temptation is ever present to make the pillars too small for the sake of the larger and quicker return of profits.

There can be no established rule laid down for the proper thickness of pillars and width of rooms, by the pillar and room system of working, as the conditions existing and the circumstances surrounding the various districts are so widely different, and ofttimes in the same locality and in the same vein of coal, conditions vary greatly. In some mines 'the roof is so soft and brittle that wide rooms are invariably forbidden. In other mines, while the roof and coal is found hard and strong, yet the bottom is soft, wet and yielding; and should it prove that the pillars have been left too weak, sooner or later a crushing weight will creep on and close that part of the mine. So that the question of the thickness of pillars and width of rooms must after all be determined by the nature of the roof, the resisting power of the pillars, and the character of the coal and under-clay.

GASES MET WITH IN MINES.

There are no coal mines in existence entirely free from gas. The gases which are formed in coal mines are evolved from the coal itself, and its associated strata, also from the decomposition of organic matter, from mine fires and the incomplete combustion of coal, wood and powder. Carburetted hydrogen gas (fire-damp) is met with in several of the mines of this State, in small quantities, but at the Brush Creek mine, in Jackson, and the Waverly mines, in Lafayette counties, this life-destroying gas is found in dangerous quantity-several lives having already been sacrificed to it. Fire-damp has proven to be, without doubt, one of the greatest dangers to be encountered in mining. This gas issues from the pores of the coal, from seams in the floor and roof of the surrounding strata; and then again, it at times bursts forth