Mining

in military affairs, is the art of blowing up any part of a fortification, building, . by gunpowder. The art of mining requires a perfect knowlege both of fortification and geometry; and by these previous helps, the engineer may be qualified to ascertain correctly the nature of all manner of heights, depths, breadths, and thickne es; to judge perfectly of slopes and perpendiculars, whether they be such as are parallel to the horizon, or such as are visual; together with the true levels of all kinds of earth. To which must be added, a consummate skill in the quality of rocks, earths, masonry, and sands; the whole accompanied with a thorough knowlege of the strength of all sorts of gunpowder