less by many of the coal-viewers !*

Coal-viewing, however, had as yet been limited to some 200 or 220 fathoms; and the views of the Messrs. Pemberton (the enterprising owners of this colliery) were not to be bounded by such ordinary depths; they considered that the thickness of the coal formation might be vastly greater where protected by the super-incumbent limestone, than where exposed to those denudations which, in the neighbourhood of the "rise" collieries, had probably swept away the strata through which their own shaft had hitherto been sunk; that they were, therefore, justified in anticipating the larger and known seams at greater depths; and that, in case these larger seams had (as was intimated) been split into smaller strata, the same causes which in other places had produced their subdivision might, at Monkwearmouth, have effected their junction. They continued, therefore, their sinking, and in October, 1834, reached a seam of considerable value and thickness, at the depth of 1578 feet below the surface; and presuming that this newly discovered seam was identified with the Bensham seam of the Tyne, (or Maudlin seam of the Wear,) they are rapidly deepening their shaft, in anticipation of reaching the Hutton or most valuable seam, at no distant period, but which (if their anticipations are well founded) will be found at a depth approaching 300 fathoms from the surface!! In the mean time, however, workings have been commenced in the supposed Bensham seam, though not as yet carried to any great extent: and when only a few days before this sheet went to press (April 1835) the writer paid a visit to the pit, he found the sinking still going on,

*Durham Advertiser.

ADITS, OR WATER DRIFTS.

189

The

the depth reached being about 265 fathoms. outlay of capital in this spirited undertaking has been immense-it is said not less than between £80,000 and £100,000.

As pertaining immediately to the province of the sinker may be mentioned the driving of thirls, or adits, for the emission of water at what are called day-levels. This was a primitive method of draining coal in situations which rendered the adoption of such an expedient available; and especially before the introduction of hydraulic machinery, or the steam engine. The particular mention of drifts to carry off the water, occurs, in connexion with the sinking of pits at Ferryhill, in a lease to the Prior of Durham dated in 1354. The old Preston Grange Colliery near Edinburgh, abandoned in 1746 on account of being inundated, discharged 220 gallons per minute, by means of a drift, into the Frith of Forth. In South Wales the numerous deep valleys intersecting the coal country, afford many favourable opportunities for this kind of drainage in general these adits are used as canals for bringing out the coals. Since the application of steam power in its most efficient forms, some gigantic undertakings for carrying off the water by day levels have been completed: the Cornish adit, for example, which drains about fifty mines, extending its ramifications about 26,000 fathoms, or nearly thirty miles, is a prodigious work of this kind: it empties itself into the sea at Falmouth harbour. The adit of the Duke of Bridgewater's collieries at Worsley is about thirty miles long, and navigable for barges used in the extraction and transit of the coals. There are several others of great extent, and that have been the subject of enormous expense in different parts of the country, particularly in the lead mining districts.

Few operations can be conceived more unpleasant and dangerous to the workmen, than the execution of these adits, especially when, as is sometimes the case, they are barely wide enough to allow the sinker to creep along. The dangers which are created by blasting the solid rock with gunpowder in such confined spaces, will be easily conceived: in the stillness of night the report of these explosions is sometimes heard to a distance of three or four miles; and the writer of this recollects on one occasion to have heard the wife of an intrepid sinker describe the feelings with which, at midnight, she used to hear when in bed, the reverberation of every shot fired by her husband in his dangerous subterranean toil, at a distance of two miles at least.

CHAPTER X.

WORKING MACHINERY.

Drawing and air shafts-Importance of Ventilation— Draining the Mine-Bearing of strata-Early contrivances for raising the water-Bucket wheelsSteam-engine-Boulton and Watt-Pumping apparatus-Subterranean Steam-engines-Deep Pits divided by Bratticing-Head Gear— Whimsey — Steam-engine and counterpoise-Hydraulic Machinery for raising Coals-Corves, Trams, Buckets, and Waggons-Screen-Entrance to Pits by Canals and Footrails.

ASSUMING, in accordance with the preceding Chapter, that a shaft is sunk to the coal, and properly secured against the irruption of loose shattery sand or gravel, as well as of water, by wood or iron tubbing, it is proper farther to state, that this shaft must either be divided down the middle by a partition of boards, so as to form upcast and downcast tubes for ventilation, and, in some cases, to serve for engine-pumps, as well as drawing coals; or else, that another pit must. be sunk, to be connected with the former by means of an underground drift, and thus afford a circulation of air. In very deep pits, the saving of expense

commonly compels the former course; in other cases, the latter method is adopted. In Staffordshire, it is usual to sink "a pair of pits"; the establishment of works for a single colliery being called "a plant,” or plantation.

That most important particular in the economy of our mines, and upon which the health and lives of the colliers so much depend—namely, Ventilation— has been the theme of a great deal of discussion— not always temperately conducted. The philanthropist has sometimes upbraided the coal-viewer with murder, for neglecting the trial of some theory of injecting or circulating air; while the viewer, in turn, has occasionally scouted, with perhaps too little ceremony, schemes which appeared ingenious and plausible enough on paper, but which might be to him obviously unavailable in practice. It will at once be apparent, that the mere existence of two or more pits at any given distance from each other, would do little, if any thing, toward cooling the interior of the mine, and changing the respirable air: the pits would simply stand, full of air, as in two vessels, under similar circumstances, water would stand at one level. Air must, therefore, be either artificially forced down one of the vents, or it must be made to descend by altering the quality of the subincumbent portion both these methods have been resorted to— the latter with most success. As the natural tendency of the atmosphere to restore its equilibrium, causes the general volume to travel by the nearest direct channel toward any place where a partial vacuum is formed; and as the object of the miner is to counteract, or rather to take advantage of, this law, stoppages are so arranged in the workings, by