Determination of the direction and inclination of a mineral deposit, Determination of a point at the surface directly above one under- A MANUAL OF MINE-SURVEYING. CHAPTER I. GENERAL EXPLANATIONS. Surveying is the art of making such measurements as are necessary to determine the relative positions of any points on the earth's surface. From such measurements a map, or plan, of any portion of the surface may be drawn, and its area calculated. All surveys are conducted upon nearly the same principles, the difference consisting in the style of instruments used in the work, and the amount of attention bestowed on the various details. Trust The branch of surveying specially applied to mining is known as Mine-surveying or, locally, as "dialling" or "latching." It consists in measuring, with a view to subsequent delineation on a plan and sections, first, the underground workings of a mine, and, secondly, the mine-buildings at the surface and the mineconcession or royalty. Thirdly, it requires an accurate method of connecting the underground- and surface-surveys. worthy plans and sections are of value for giving a condensed view of all the facts connected with the works and explorations of a mine; for affording data to assist in the further prosecution of workings after temporary abandonment of the excavations; and for the avoiding of destructive and lamentable effects— such, e.g., as disastrous litigation respecting trespass on adjoining royalties, loss caused by driving in the wrong direction, or irruptions of water, quicksand, or firedamp, giving rise to loss of life and property-which have too often resulted from incorrect or imperfect mine-plans. Historical Sketch. The origin of mine-surveying must be sought with that of mining in very early times. The oldest mine-plan known is a papyrus, preserved in the museum at Turin, depicting the workings of an Egyptian gold-mine. It was drawn in the reign of the king Mineptah, 1,400 years before the Christian era. Land-surveying was first practised in Egypt. There the annual overflows of the Nile, and the consequent deposit of mud, destroyed the land-marks of the different proprietors, so that it became necessary to determine them by measurement every year. The oldest evidence of the solution of mathematical problems is afforded by a papyrus in the British Museum, which is believed to have been copied, 1,700 years B.C., from a much older work. It gives rules for the calculation of areas of triangles, trapezoids, and circles. That the important mines of the ancient Greeks necessitated the solution of mine-surveying problems is shown by the fact that such problems are fully discussed by Hero of Alexandria (B.C. 285-222), several of whose works are extant. The greatest advance in survey practice made by Hero was his invention of the diopter, a sighting instrument for surveying purposes. The oldest instrument for measuring angles, like the cross-head which is still in use, only permitted right angles to be set out. This primitive instrument consisted of two straight-edges fastened together at right angles, a pointed vertical staff being fixed to the point of intersection. The two straight-edges were provided at each extremity with sight vanes, from which plumb-lines were suspended so as to enable the instrument to be levelled. With Hero's improved instrument, any angle could be measured. Indeed, it must be regarded as the origin of the highly perfect theodolite of the present day. It consisted essentially of a beam resting between two uprights on a pillar-like stand. The beam was movable in both directions by means of spiral screws acting on horizontal and vertical cog-wheels. It was hollowed out, and contained a metal tube, at right angles to which were glass cylinders at each end of the beam. The cylinders had special covers made of metal plate, which could be raised or lowered by means of screws. They were furnished with vertical and horizontal slits for sighting. The instrument was thus a combined theodolite and level. Two staves with sliding circular vanes were used in conjunction with it. From the beginning of the Christian era until the Middle Ages, mining records are wanting. An ancient charter relative to the mines of the Mendip Hills is in existence. Of this Mr. Robert Hunt gives a fac-simile in his British Mining. It dates from the reign of Edward IV., about 1480. It is a rude attempt at plan-drawing, representing the "Myne deeps," as they were then called. The first writer who treated mining systematically, Georgius |