Where the ground admits, it is considered the best mode of working veins, to commence at the back of a coal eminence, or as low as possible, and work up, filling the excavation with slate and fine coal, leaving a horizontal passage for the coal barrows. A section of a wide vein near Pottsville, has been wrought by this mode several hundred feet into the hill. The same vein is explored from parts of the summit by vertical and inclined shafts. The coal and slate handled, are raised by horse-power, in wagons by a rail-way that has the inclination of the vein. Veins of coal alternate with gray wacke slate in the hill. Vegetable impression sometimes occur in the argillaceous schist that forms the roof of the Pottsville coal veins. The western part of Pennsylvania is abundantly supplied with bituminous coal, as the eastern is with anthracite. It is found on the rivers Conemaugh, Alleghany, and Monongahela, and in numerous places to the west of the Alleghany ridge, which is generally its eastern boundary; it occurs on this mountain at a considerable elevation, and elsewhere, in nearly a horizontal position, alternating with gray sand-stone that is often micaceous and bordered by argillaceous schist. The veins are generally narrow, rarely over six feet in width. This mineral is abundant and of good quality near Pittsburg, where it is valuable for their extensive manufactures. Beds of bituminous coal are reported as occurring in Bedford county, in the north-west part of Luzerne, and in Bradford county. In the last county, nine miles from the Susquehanna, there is an extensive bed of coal, regarded as bituminous. It has been penetrated thirty feet without fathoming the depth of the strata. Bituminous coal is abundant in Tioga county, state of New York. The summit level is forty-four feet above the river, and upwards of four hundred above the lake. It occurs on the Tioga, and on the Chemung, a branch of that river. Bituminous coal exists on the numerous streams that descend the western side of the extensive peninsula, situated between the north and west branches of the Susquehanna. The appearance of the Tioga, or bituminous coal, differs but little from the best Liverpool or Newcastle coal. Its color is velvet black, with a slight resinous lustre, its structure is slaty or foliated, and its layers as in the best English coal, divided in prismatic solids, with bases slightly rhomboidal; it is easily frangible, and slightly soils the finger. It burns with a bright flame and considerable smoke, with a slight bituminous smell, a sort of ebullition taking place, and, as the heat increases, an appearance of semi-fusion leaving a slight residue or scoria.