A Treatise on Mine-surveying

accuracy accurate adjustment angle attached axis base bearing brass calculated centre circle clamped Cloth compass consists construction cord corner correct course departure determined dial diameter difference direction distance divided divisions drawn east Edition employed Engineering equal error fathoms feet figure fixed given gives glass graduated ground half height hole horizontal Illustrations inches inclination instrument iron known latitude latter length lode magnetic marked means measured meridian method miner's mines moved necessary needle noted object observations obtained parallel passing perpendicular placed plane plate plotting position practical reduced represent right angles rule scale screw shaft shown side sights square staff station surface survey taken telescope theodolite traverse triangle turned underground usually vernier vertical wire yards