2. A very thin seam of shed of coal.

COAL PRINTS (N.). Thin films or patches of coallike matter interbedded with shale, &c.

COAL-RAKE (D.). A seam or bed of coal.

COAL ROAD. An underground roadway or heading, made or driven entirely within the seam, or one having a coal roof and floor as well as coal sides.

COAL SALAD (S. W.). A mixture of various sorts of coal.

COAL SEAM. See Coal Bed.

COAL SHALE (F.D.). See Coal Measures.

COAL SHED. A bed of coaly matter only a few inches in thickness, and therefore unworkable.

COAL SMITS (Y.). Worthless, earthy coal. See Coal Smut.

COAL SMUT. A black, earthy coaly stratum at or near the surface. The outcrop of a coal seam.

COAL WARRANT (N. W.). A kind of clunch or fireclay forming the floor of a coal seam.

COAL WASHING. See Washing Apparatus.

COAL WORK (N.). Headings, &c., driven in a seam of coal.

COB (D.). A small solid pillar of coal left in a waste as a support for the roof.

COBBLES. Round coal in smallish lumps.

COBBLING. Cleaning the roads in the pit of coals which have fallen off the trams during the turn (1).

COCKERMEGS.

Timber props fixed in the manner

shown in Fig. 42, to support the coal during holing.

COCKERPOLE. A piece of timber placed horizontally between two inclined pieces which abut against the roof and floor. See Fig. 42, Cockermegs.

COCKERS. See Cockermegs.

COCKERSPRAGGS, See Cockermėgs.

COCKHEAD (D.). A description of pack or support to the roof of a waste, consisting of a gobbin of slack or rubbish about 12 feet in width, surmounted by a few lumps of coal.

COFFERING. Watertight casing or walling of a shaft without the employment of metal tubbing. It consists in lining the shaft to stop the influx of feeders of water where the head of water is not great by means of brickwork set in hydraulic mortar backed with puddled clay or with soil; the water being allowed to escape down a wooden pipe called a plug-box during the putting in of the coffering.

COG. 1. See Chock.

2. (S. S.) A pack, which see.

COG AND RUNG-GIN. One of the earliest appliances

for raising the coals and water from coal pits. It was a kind of windlass fitted with a cog-wheel and pinion arrangement, and worked by a horse in much the same way as our nineteenth century horse-gins are worked.

COGGER. One who builds up cogs (1) (2).

COGGING (S. S.). The propping up of the roof in longwall stalls.

COKE-COAL (N.). Carbonised or partially burnt coal found on the sides of whin dykes.

COKING COAL. A coal having the property of being converted into large and hard cokes, free from sulphur, &c.

COLD FURNACE (N.). A drift driven up into an upcast shaft to convey the return air into it instead of passing it over the furnace fire. This is done to guard against any gas in the return air firing (3) from the heat of the furnace.

COLD PIT (Lei.). A downcast pit. Called cold because the fresh or cold air comes down it.

COLLAR (N.). The mouth of a pit-shaft.

COLLAR-CRIB (N.). A strong oak polygonal frame fixed in a shaft, upon which the wooden wedging crib of solid wood tubbing is bedded.

COLLARING. Timber framing for steadying and supporting pump trees in a shaft. See Chogs, Fig. 40.

COLLIER. 1. Strictly speaking, a man who cuts or hews coal with a pick, though commonly applied to any one who works in or about a colliery,

2. A steam or sailing vessel carrying a cargo of coals from staithes and drops (2) coast wise.

COLLIER'S COALS. A certain weight of coals allowed periodically (once in a month or six weeks) by the owners to the colliers (1) and other men employed on the works, who are in most cases householders, as a perquisite. The colliers, however, are not as a rule paid for cutting and hauling these coals.

COLLIER'S (1) TON. A weight of often several cwt. in addition to the standard ton or 2240 lbs. In former times as much as 28 cwt. was reckoned as one ton.

COLLIERY. A place where coal is mined, with its machinery and plant.

COLLIERY CONSUMPTION. The amount of fuel consumed in generating steam and for other purposes in and about a colliery establishment.

COLLIERY WARNINGS. Telegraphic messages despatched from the Government meteorological stations to the principal colliery centres to warn the managers of mines when any sudden fall of the barometer is taking place, in order that extra vigilance and care may be taken in guarding against the effects of possible sudden outbursts of fire-damp, or of unusually large quantities of that gas being given off from old workings, &c., as a consequence of a reduced atmospheric

pressure.

COLUMN. 1. The rising main (either fixed vertically or inclined) or length of pump-trees or pipes conveying the water from the mine to the surface.

2. Ventilating column, which see.

3. See Carrot.

COMB COAL.

COME (Come Water). The constant or regular flow of water in a mine proceeding from old workings or from watery rocks.

COMET (S. W.). An open-burning hand lamp with a long torch-like flame.

COMING UP TO GRASS or COMING UP to Day. A common term used by miners for the word Basset.

COMPANY. A number of butty colliers who work and carry on a stall, &c.

COMPOUND VENTILATION (N.). The system, first practised by Buddle, of dividing up or splitting the air, and of ventilating the workings of a coal mine by giving to each district or panel a separate quantum of fresh air, and conveying away the return air to a main return direct from each panel.

CONDUCTORS. See Cage Guides.

CONE-IN-CONE COAL. Steam or anthracite coal exhibiting a peculiar fibrous structure passing into a singular toothed arrangement of the particles called cone-in-cone coal or crystallised coal.

CONICAL DRUM. The rope roll or drum of a winding engine constructed in the form of two truncated cones placed back to back, the outer ends or sides being usually the smallest in diameter. See Fig. 43. The winding ropes are wound and unwound in a spiral form, and rest in channels or grooves of iron riveted upon the