The ground is secured by timbering, or more usually by arching in masonry or brick-work.
The latter includes not only the actual excavation of the mineral, but also haulage and hoisting by which it is brought to the surface, timbering and other means of supporting the excavations, and the drainage and ventilation of mines.
This plan has the advantage of requiring little or no timbering when the mineral is strong enough to stand well in the pillars and when the hanging wall is good.
This method of mining requires but little timbering, FIG.
The wool-growing industry has been almost entirely destroyed by the competition of Australia and the West, and the people are now engaged mainly in dairy-farming, timbering, graniteand marble-quarrying, and in keeping summer boarders.