THE KEYSTONE COLLIERY is on the north dip of the Locustdale basin, and on the same coal-beds which are worked by the Locustdale Coal Company on their south dips. The character and extent of this basin will be found fully discussed in the body of this book, in the general description of the Mahanoy Region—the application is as pertinent to the Keystone as to the Locustdale colliery.
The present operations at this colliery are above water level, by two drifts on the Mammoth, or a water level gangway and a counter level on the upper range of breasts. The height of "breasting," which ranges from 150 to 200 yards, is too great to be worked by a single range of breasts, therefore they are divided into the upper and lower levels. The "run" is one mile west, above the natural drainage, and one mile west and 900 yards east, below, on the Mammoth; but on the underlying seams, the Skidmore, Buck Mountain, &c., the " run" is 2,660 yards east and west.
It is claimed that coal enough remains above water level, in this colliery, to last for ten years, with an average production of 500 tons per day, while the quantity below water level, to the centre of the basin, is immense. The calculation of the production may be approximately made, by adopting the angles and measure ments given in figure 58, page 210, while the number and relative position and thick ness of the coal-beds are given in figure 59, page 212.
The present capacity of the Keystone colliefy is about 500 tons per day. It is estimated, however, that 1,000 tons per day can be produced from this single col liery, by operating both above and below water level, and we have no doubt of the fact. The steam capacity is 170 horse-power. The character of the coal is well established, and enjoys a high reputation. J. Louden Beadle's exhaust fan is used and the ventilation of the mines is perfect.