C2H3 and C3Hg, where C:H=7.98 and C:0+N=46.3. In cannel coals the prevailing constituents are the spores of cryptogamic See also:

• PLANTS

273), differences in composition are mainly See also:

• ORIGINAL

Going northward the beds of limestone diminish in thickness, with a proportional increase in the intercalated sandstones and shales, until in See also:

• SCOTLAND
• SCOTLAND, CHURCH OF
• SCOTLAND, EPISCOPAL CHURCH OF

Seams of a See also:

• MEDIUM

Coal has also been found in an See also:

• EXTENSION (Lat. ex, out ; tendere, to stretch)

They are widely distributed throughout See also:

• CHINA

Coal is known at sever-al points in See also:

• ALASKA

. 1905 3,202,911 Russia . . 1904 19,318,000 See also:

• HOLLAND
• HOLLAND, CHARLES (1733–1769)
• HOLLAND, COUNTY AND PROVINCE OF
• HOLLAND, HENRY FOX, 1ST BARON (1705–1774)
• HOLLAND, HENRY RICH, 1ST EARL OF (1S9o-,649)
• HOLLAND, HENRY RICHARD VASSALL FOX, 3RD
• HOLLAND, JOSIAH GILBERT (1819-1881)
• HOLLAND, PHILEMON (1552-1637)
• HOLLAND, RICHARD, or RICHARD DE HOLANDE (fl. 1450)
• HOLLAND, SIR HENRY, BART

1905 72,665 See also:

• AUSTRALASIA

J. R. H.; H. M. R.) Coal-Mining. The opening and laying out, or, as it is generally called, "winning," of new collieries is rarely Preliminundertaken without a ary trial preliminary examination ofcoalof the character of the workings. strata by means of borings, either for the purpose of determining the Coal resources of Great Britain. District. Coalfield. I. II. III. A South Wales and See also:

• MONMOUTHSHIRE

Warwickshire 1,448,804,556 321,822,653 1,126,981,903 See also:

• LEICESTERSHIRE

1 See also:

• BORE

In 1873 there could be seen, in the thick coal seams of Bengal, near Raniganj, a seam about 5o ft. thick laid See also:

• BARE

The actual coal measure strata, consisting mainly of shales and See also:

• CLAYS, PAUL JEAN (1819-1900)

Air is then forced into the inclosed space by means of a compressing See also:

• ENGINE
• ENGINE (Lat. ingenium)

With increase in depth, however, the thickness and weight of the cast iron tubbing in a large shaft become almost unmanageable; in one instance, at a depth of 1215 ft., the bottom rings in a shaft 14 ft. in diameter are about 4 in. thick, which is about the limit for See also:

• SOUND
• SOUND, THE (Danish Oresund)

When hard ground is reached, a seat is formed for the cast iron tubbing, which is built up in the usual way and concreted at the back, a small quantity of See also:

• CAUSTIC (Gr. rcavvraubs, burning)

Where the water does not accumulate very rapidly it is a common practice to allow it to collect in a pit or sump below the working bottom of the shaft, and to draw it off in a water tub or" hoppet "by the main engine, when the latter is not employed in raising coal. The laying out of a colliery, after the coal has been woh, by sinkings or levels, may be accomplished in various ways, according to the nature of the coal, its thickness and dip, and the extent of ground to be worked. In the South uYing Staffordshire and other Midland coalfields, where only workings. shallow pits are required, and the coals are thick, a pair of pits may be sunk for a very few acres, while in the North of England, on the other hand, where sinking is expensive, am area of some thousands of acres may be commanded from the same number of pits. In the latter case, which represents the most approved practice, the sinking is usually placed about the centre of the ground, so that the workings may radiate in every direction from the pit bottom, with the view of employing the greatest number of hands to advantage. Where a large area cannot be commanded, it is best to sink to the lowest point of the field for the convenience of drawing the coal and water which become level-free in regard to the pit. Where properties are much divided, it is always necessary to maintain a thick barrier of unwrought coal between the boundary of the mine and the neighbouring workings, especially if the latter are to the dip. If a prominent line of See also:

• FAULT (Mid. Eng. faute, through the French, from the popular Latin use of fallere, to fail; the originallof the Latin being replaced in English in the 15th century)

These may, however, all be considered as modifications of two systems, viz. pillar work and long-wall work. In the former, which is also known as "See also:

• POST

The space from which the entire quantity of coal %j r z ~ d 1,!; / /////a ~ L~ , 1/1%141 4d !i f n4h / z., - :://h fri C,, - d1 Grp A % soaves Reference —f Direction of air current Air crossing a a Doors Air split S Stoppings erattices has been removed is known in different districts as the " See also:

• GOAL

The character of such workings is very irregular in plan, and as the ventilation is attended with considerable difficulty, it is now becoming generally superseded by more improved methods. The second great principle of working is that known as long- wall or long-work, in which the coal is taken away either in broad ong-wau faces from roads about 40 or 5o yds. apart and parallel working. to each other, or along curved faces between roads radiating from the pit bottom—the essential feature in both cases being the removal of the whole of the coal at once, without first sub-dividing it into pillars, to be taken away at a tl - MMACL face to protect the workmen, and allow them to work together behind. The general character of a long-wall working is shown in fig. 7, which represents an area of about 50o acres of the bottom hard steam coal at See also:

• SHIPLEY
• SHIPLEY, JONATHAN (1714-1788)

6 is sub- stantially a modification of this kind of long-wall work. South Fig. 8 represents a method of working practised in Yorkshire the South Yorkshire district, known as bords and method. See also:

• BANKS, GEORGE LINNAEUS (1821-1881)
• BANKS, NATHANIEL PRENTISS (1816–1894)
• BANKS, SIR JOSEPH
• BANKS, THOMAS (1735-1805)

Where the whole of the coal is removed at once there is less See also:

• CHANCE (through the O. Fr. cheance, from the Late Lat. cadentia, things happening, from cadere, to fall out, happen; cf. " case ")

r/f /, %/ / . a//v' n ' d::,r/ it/'/;i /era "rA Reference , CS Doors g S Stopping* / Air crossing ' g Y/i~%~j 4 i* II OG/i See also:

• EMS

As each stage is worked out, the floor level is connected with that next below it by means of an incline, which facilitates the introduction of the packing material. Stuff containing a considerable amount of clay is found to be the best suited for the purpose of filling, as it consolidates readily under pressure. In France and Germany the method of filling the space left by the removal of the coal with waste rock, quarried under-ground or sent down from the surface, which was originally used in connexion with the working of thick inclined seams by the method of horizontal slices, is now largely extended to long-wall workings on thin seams, and in Westphalia is made compulsory where workings extend below surface buildings, and safety pillars of unwrought coal are found to be insufficient. With careful packing it is estimated that the surface subsidence will not exceed 40% of the thickness of the seam removed, and will usually be considerably less. The material for filling may be the waste from earlier workings stored in the spoil banks at the surface; where there are blast furnaces in the neighbourhood, granulated slag mixed with earth affords excellent packing. In thick seams packing adds about 5d. per ton to the cost of the coal, but in thinner seams the advantage is on the other side. In some anthracite collieries in America the small coal or See also:

• CALM

This is some-times obviated by holing in the beds below the coal, or in any portion of a seam of inferior quality that may not be See also:

• WORTH
• WORTH, CHARLES FREDERICK (1825-1895)

In Yorkshire hollow square pillars, formed by piling up short blocks of wood or chocks, are often used instead of props formed of a single See also:

• STEM (O. Eng. staefn, stemn, cf. Du. stain, Ger. Stamm, &c., probably related to " staff ")

The weight is about 15 cwt. At a working speed of 6o yds. per shift of 6 hours, the work done corresponds to that of twelve average men. The width of the groove cut is from 2 to 3 in. at the face, diminishing to 12 in. at the back, the See also:

• PRO

The whole operation requires from 8 to ro minutes, giving a cutting speed of 120 to 150 sq. ft. per See also:

• HOUR

W. E. Garforth's See also:

• DIAMOND

The removal of the coal broken at the working face to the pit bottom may in small mines be effected by hand labour, but more under- generally it is done by horse or See also:

• MECHANICAL

In some cases steam generated in boilers at the surface is carried in pipes to the engines below, but there is less loss of power when compressed air is sent down in the same way. Underground boilers placed near the up-cast pit so that the See also:

• SMOKE (from O. Eng. smeocan, to smoke, reek, cf. Dutch meek, Ger. Schmauch, probably allied to Gr. vol9caiv)

The three last may be considered as modifications of the same principle. In the first, which is that generally used in Northumberland and Durham, a single line of rails is used, the loaded tubs being drawn ".out bye," i.e. towards the shaft, and the empty ones returned " in bye," or towards the working faces, by See also:

• REVERSING

The forward edge of the tub carries a projecting See also:

• PIN (a doublet with " pen " from Lat. pinna, feather, pinnacle, which is said to contain the same root as irirvs, pine tree, and properly to mean a sharp point or end)

The wagons are attached at intervals by short lengths of chain lapped twice round the rope and hooked into one of the links, or in some cases the chains are hooked into hempen loops on the main rope. In mines that are worked from the outcrop by adits or See also:

• DAY (O. Eng. dreg, Ger. Tag; according to the New English Dictionary, " in no way related to the Lat. dies")
• DAY, JOHN (1574-1640?)
• DAY, THOMAS (1748-1789)

The return air from fiery workings is never allowed to approach the furnace, but is carried into the upcast by a special channel, called a dumb drift, some distance above the furnace drift, so as not to come in contact with the products of See also:

• COMBUSTION (from the Lat. comburere, to burn up)

By the use of the spiral guide casing and the chimney the velocity of the effluent air is gradually reduced up to the point of final discharge into the atmosphere, whereby a greater useful effect is realized than is the case when the air streams freely from the circumference with a velocity equal to that of the rotating fan. The power is applied by steam acting directly on a crank at one end of the See also:

• AXLE (in Mid. Eng. axel-tre, from O. Norweg. oxull-tre, cognate with the O. Eng. exe or eaxe, and connected with Sansk. dksha, Gr. a wv, and Lat. axis)

The actual See also:

• CONVEYANCE

The use of small See also:

• AUXILIARY (from Lat. auxilium, help)

W. See also:

• THOMAS
• THOMAS (c. 1654-1720)
• THOMAS (d. 110o)
• THOMAS, ARTHUR GORING (1850-1892)
• THOMAS, CHARLES LOUIS AMBROISE (1811-1896)
• THOMAS, GEORGE (c. 1756-1802)
• THOMAS, GEORGE HENRY (1816-187o)
• THOMAS, ISAIAH (1749-1831)
• THOMAS, PIERRE (1634-1698)
• THOMAS, SIDNEY GILCHRIST (1850-1885)
• THOMAS, ST
• THOMAS, THEODORE (1835-1905)
• THOMAS, WILLIAM (d. 1554)

The conclusions arrived at by the royal commission of 1891, which may be taken as generally representative of the views of British colliery See also:

• ENGINEERS, MILITARY

'Acid. Oyg Gas. gen. Bituminous Cwm Clydach . 19'72 5'44 1.05 63'76 29.75 it . 14.34 9'43 2'25 31.95 56'34 Steam See also:

• NAVIGATION (from Lat. navis, ship, and agere, to move)

This is now generally done, and in some countries is compulsory, when the rocks are deficient in natural moisture. In one instance the quantity of water required to keep down the dust in a mine raising 85o tons of coal in a single shift was 28.8 tons, apart from that required by the jets and motors. The distributing network extended to more than 30 M. of pipes, varying from 31 in. to r in. in diameter. In all British coal-mines, when gas in dangerous quantities has appeared within three months, and in all places that are _ dry and dusty, blasting is prohibited, except with ploal SafetysX " permitted " See also:

• EXPLOSIVES

A more extended application of the same principle was made in the apparatus of L. Denayrouze by which the air, contained in cylinders at a pressure of 300 to 350 lb per sq. in., was supplied for respiration through a reducing See also:

• VALVE (Lat. valva, a leaf of a double or folding door, allied to volvere, to roll, as of a door on its hinges)

Experiments have also been made with a See also:

• DEVICE

In the large shafts of the Northern and Wigan districts the cages are made about 8 ft. long and 31 ft. broad, being sufficient to carry two large trams on one See also:

• DECK

Many colliery managers, however, prefer to have only two opposite guides, as being safer. The cage is connected by tubular clips, made in two pieces and bolted together, which slide over the ropes. In addition to this it is necessary to have an extra system of fixed guides at the surface and at the bottom, where it is necessary to keep the cage steady during the operations of loading and landing, there being a much greater amount of oscillation during the passage of the cage than with fixed guides. For the same reason it is necessary to give a considerable clear- ance between the two lines of guides, which are kept from 15 to 18 in. apart, to prevent the possibility of the two cages striking each other in passing. With proper precautions, however, wire guides are perfectly safe for use at the highest travelling speed. The cage is connected with the drawing-rope by short lengths of chain from the corners, known as tackling chains, gathered into a central ring to which the rope is attached. Ropes and Round steel wire-ropes, about 2 in. in diameter, are chains. now commonly used; but in very deep pits they are sometimes tapered in section to reduce the dead weight lifted. Flat ropes of steel or iron wire were and are still used to a great extent, but round ones are now generally preferred. In Belgium and the north of France flat ropes of See also:

• ALOE

Ultimately also the ropes should be reversed in position, and this can only be done with a rope of See also:

• UNIFORM

For flat ropes the drum or bobbin consists of a solid disk, of the width of the rope fixed upon the shaft, with numerous parallel pairs of arms or horns, arranged radially on both sides, the space between being just sufficient to allow the rope to enter and coil regularly upon the preceding See also:

• LAP

In Belgium it was tried in a pit 940 metres deep, where it has been replaced by flat hempen ropes, and is now restricted to shallower workings. In Westphalia it is applied in about thirty different pits to a maximum depth of 761 metres. A novelty in winding arrangements is the substitution of the electromotor for the steam engine, which has been effected in a few instances. In one of the best-known examples, the Zollern colliery in Westphalia, the Koepe system is used, the winding disk being driven by two motors of 12oo H.P. each on the same shaft. Motion is obtained from a continuous-current generator driven by an alternating motor with a very heavy See also:

• FLY (formed on the root of the supposed original Tent. fleugan, to fly)

The opposite axes are connected with springs which are kept in compression by tension of the rope in drawing but come into action when the pull is released, the side axes then biting into wooden guides or gripping those of steel bars or ropes. The use of these contrivances is more common in collieries on the continent of Europe, where in some countries they are obligatory, than in England, where they are not generally popular owing to their uncertainty in action and the constant See also:

• DRAG (from the Old Eng. dragan, to draw; the word preserves the g which phonetically developed into w)

When the cage has several decks, it is necessary to repeat this operation for each, unless there is a special See also:

• PROVISION (Lat. provisio)

Silksworth Colliery, North. 1 535,000 tons in a year for shaft umberland . . . 58o yds. deep, two engines. See also:

• BOLSOVER

The nature and extent of these operations vary with the character of the coal, which if hard and free from shale partings may be finished by simple screening into large and See also:

• NUT
• NUT (0. Eng. knutu, cf. Dutch noot, Ger. Nuss; allied with Gael. cno; it is not of the same form as Lat. nux)

Anthracite coal in Pennsylvania is subjected to breaking between toothed rollers and an elaborate system of screening, before it is See also:

• FIT

1065 3494 Agrappe, See also:

• MONS (Flemish Bergen)

Under such conditions work would be practically impossible except with very energetic ventilation and dry air. It would be scarcely possible to circulate more than 120,000 to 130,000 cub. ft. per minute under such conditions, and the number of working places would thus be restricted, and consequently the output reduced to about 500 tons per shift of io hours, which could be raised by a single engine at the surface without requiring any very different appliances from those in current use. In the United Kingdom the ownership of coal, like that ofother minerals, is in the proprietor of the soil, and passes with it, except when specially reserved in the sale. Coal lying under the sea below low-water See also:

• MARK
• MARK, CARL (1858– )
• MARK, GOSPEL OF ST
• MARK, ST

• 135 Total . 1129 The principal See also:

• SOURCES

It continues the table of former See also:

• OFFICIAL (Late Lat. QJicialis, for class. Lat. apparitor, from officium, office, duty)