CHAPTER XVIII. MINE PLANS. Plan and Section. For the representation of mine workings a plan and a vertical section are required. The plan is a projection of the mine workings on a horizontal plane; the section is a projection of the workings on a plane running parallel to the main longitudinal direction of the mine. With complicated and irregular mines, one section is not sufficient. In such a case, several sections have to be made in given directions. (a.) Metalliferous Mines.-Four drawings are necessary in order to represent a metalliferous mine-(1) the ground plan; (2) the working plan; (3) a longitudinal section; (4) a transverse section. The ground plan gives a general representation of the whole concession. It may be on a scale of about 3 chains to the inch, and on it the boundary of the property of every land owner should be distinctly marked, and all the lodes indicated. The working plan gives a general view of the underground workings, as they would be seen from above if the ground was transparent. This plan should be drawn on a large scale, 4, 5, 8, and 10 fathoms to the inch being scales used for the purpose. The longitudinal section is drawn on the supposition that a section of the ground is cut away, and that a side view of the mine is exposed. All the vertical shafts, the stopes, the dip of the orecourses, and the surface-line with elevations of the mine buildings, will be correctly shown. The levels, diagonal shafts, and winzes will have a false appearance. The levels will appear perfectly straight however crooked their course may be, the diagonal shafts and winzes will appear perpendicular, and the cross-cuts will be represented as open doorways. The transverse section is of great value, as it shows the dip of the ore-courses. In the transverse section, the view is taken at one end of the workings, at right angles to the longitudinal section. Thus, the inclination of the shafts and winzes sunk on the lode is shown. The levels driven on the lode will be represented as open doorways; the cross-cuts are correctly shown; and all variations in the dip of the lode may be seen from the surface to the bottom of the mine. When the lode is very flat, as at the Cornish mines of Wheal Jane and Wheal Kitty, the section is made along the lode. In 50 40 ૩૧ 20 10 ADIT. Fig. 91.-Transverse Section. this way a true idea is given of the ground worked; but an erroneous one with regard to depth. This method of projecting the section is necessary to enable the ground stoped away to be shown, as when the lode is so very flat, the back of one level in a vertical section would touch the floor of the next. As a rule, lodes are so vertical that a perpendicular plane may be taken for the section. The workings of a metalliferous mine are represented in Figs. 90, 91, on a scale of about 20 fathoms to the inch. The mine has an adit-level and below that, 10-, 20-, 30-, 40-, and 50-fathom levels. The adit is north of the shaft. The engine shaft contains the pumps which lift the water from the sump or lowest point of the shaft to the adit-level, which comes out to the surface on the adjacent hill side. This shaft was sunk vertically to intersect the lode at the 10-fathom level, a cross-cut being driven to the adit. Then, instead of continuing vertically, necessitating the driving of cross-cuts to the lode, the shaft follows the latter. The shaded portions shown in the longitudinal section represent the projection of the ore masses, removed by stoping. In practice, such portions are not shaded but coloured-purple for tin, green for copper, blue for lead, &c. Between the 10- and 20-fathom levels a mistake arose, the winze and rise did not meet owing to an error of the dialler. It will be found advisable to colour all the levels on one lode the same tint. Formerly it was the general practice to colour each level a different colour, the adit-level being blue, and the levels below it red, green, yellow, violet, and brown in succession. No scale is prescribed by law for the plans of the British metalliferous mines. The variety of scales used presents great difficulties with regard to the comparison of the plans of different neighbouring mines. In many districts, the plans are prepared in a slovenly and unsatisfactory manner. This is notably the case in the Derbyshire lead mines. There, according to Mr. A. H. Stokes, H.M. Inspector of Mines for that district, the majority of the mines have no plans whatever. Even at the larger mines which have plans, they are very roughly drawn and rarely indicate the extent to which the ore has been worked.. The variable width of the levels is not shown, the latter being represented by a coloured line. The position of the best and most profitable parts of the mine, that is, the width to which the ore has been extracted, is shown as an ordinary narrow heading. In fact, the plans are not true representations of the mine, but merely represent the length of underground tramways. Sections of the mine are seldom made. (b.) Colliery Plans. By the Coal Mines Regulation Act, 1887, the owner, agent, or manager of every colliery is compelled to keep, in the office at the mine, an accurate plan of the workings of the mine up to a date not more than three months previously, and the general direction and rate of dip of the strata, together with a section of the strata sunk through, or if that be not reasonably practicable, a statement of the depth of the shaft, with a section of the seam. Every such plan must be on a scale not less than that of the Ordnance Survey of 25 inches to the mile. Representing collieries on a plan is a much more simple operation than representing metalliferous mines. The workings are projected on a horizontal plane. The coal withdrawn is coloured dark, and the direction of the air-current indicated by arrows. The intake air-current is coloured blue, and the return air-current red. The water-courses may be coloured green, drowned waste also green, and faults bright red shaded off on the dip. Main doors may be indicated by a D in blue, main stoppings by blue lines, and caution-boards by a C in red. heights of the different points above the level of the shaft-bottom should be shown in red figures, and those below the level of the shaft-bottom in blue. The signs shown in Fig. 92 are employed on colliery plans. The When two or more seams are worked one above the other, and are shown on the same plan, they are distinguished by means of colour. Admirable illustrations of the manner in which colliery plans should be executed are afforded by the plans which accompany the annual reports of H.M. Inspectors of Mines. Surface Plans. The surface plan of a colliery or metalliferous mine requires great distinctness of detail. If the scale of about 25 inches to the mile is adopted, the conventional signs used on the maps of the Ordnance Survey should be employed. If the scale is larger, care must be taken to give the conventional signs such dimensions as will accord with the scale of the plan. Buildings are coloured crimson lake for houses, and dark grey (a light wash of indian ink) for outbuildings. The mine buildings may be distinguished from other buildings shown on the plan by having a darker tint of red. In representing objects on the plan, their natural colours are sometimes adhered to; in other cases a conventional colour is used. Thus, for grass land, a flat |