Page:EB1911 - Volume 18.djvu/554

 For fuller information see also J. L. Propert, History of Miniature Art (London, 1887); G. C. Williamson, History of Portrait Miniatures (2 vols., folio, 1904), Portrait Miniatures (London, 1897); Richard Cosway (London, 1897); George Engleheart (London, 1902); Andrew Plimer, &c. (London, 1902); How to Identify Miniatures (London, 1904); Richard Cosway (London, 1905), and the privately printed catalogue of the Pierpont Morgan Collection (1906, 1907, 1908); Les Émaux de Petitot du Louvre (Paris, 1862–1864); catalogues of the Buccleuch Gallery, Welbeck Gallery, Ward Usher Collection, Bemrose Collection, Woburn Abbey Collection, all privately printed, the catalogue of the collection exhibited at South Kensington, and the privately issued catalogue at the Burlington Fine Arts Club, with illustrations.

MINIM (adapted from Lat. minimus, the smallest; a superlative formed from the Indo-Germanic root min-, small), the smallest possible part of a thing, a particle. In music the name “minim” (nota minima) was given by medieval musicians to a note whose value was half a semibreve. It was, as its name implies, the note of the shortest duration then in use. In modern music several notes of lesser value, as the “crotchet” and “quaver,” have been added, and the minim is now about halfway in the scale of “values.” According to Thomas Morley (A Plaine and Easie Introduction to Practical Music, 1597), its introduction into manuscript music is ascribed to Phillipus de Vitriaco, a musician of the 14th century.

In medicine a minim is the smallest fluid measure, being equal to one drop. Sixty minims make a fluid drachm.

For the religious Order known as “Minims” see.

MINING, the general term for the working of deposits of valuable mineral. The term is not limited to underground operations, but includes also surface excavations, as in placer mining and open-air workings of coal and ore deposits by methods similar to quarrying, and boring operations for oil, natural gas or brine. Mining may be subdivided into the operations of prospecting or search for minerals, exploration and development, work preparatory to active operations, and working. 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. Finally, under the heads of administration, mine valuation, mining education, accidents, hygiene and mining law, will be discussed matters having important bearing on mining operations. Special methods of mining are dealt with in the separate articles on, , and other minerals and metals. and, which may be considered as branches of mining, are also discussed in separate articles.

Prospecting.—In the article on (q.v.) the distribution and mode of occurrence of the useful minerals and ores are fully discussed. The work of prospecting is usually left to adventurous men who are willing to undergo privation and hardship in the hope of large reward though the chances of. success are small. The prospector is guided in his search by a knowledge of the geological conditions under which useful minerals occur. When the rocks are concealed by detrital material he looks for outcroppings on steep hillsides, on the crests of hills or ridges, in the beds of streams, in landslides, in the roots of overturned trees, and in wells, quarries, road-cuttings and other excavations. When the solid rock is not exposed the soil sometimes furnishes an indication of the character of the underlying rock. Sometimes the vegetation, shrubs, trees, &c., as characteristic of certain soils, may furnish evidence as to rock or minerals below. Search should be made in the beds of streams and on the hillsides for “float mineral” or “shoad stones,” fragments of rocks and minerals known to be associated with and characteristic of the deposits. Fragments of coal, or soil stained black with coal, will be found near the outcrop of coal beds. Grains of gold or particles of ore may be detected by washing samples of gravel in a prospector’s pan. By tracing such indications up the stream or up the hillside the outcrop may sometimes be found, or at least approximately located. The outcrop of a metalliferous vein frequently manifests itself as a line of rocks stained with oxide of iron, often honeycombed and porous, the “gossan” or “eisen-hut,” the iron oxide of which results from the decomposition of the pyrites, usually present as a constituent of such veins. Other metals, such as manganese, copper, nickel, may show their presence by characteristic colours. Finally, the surface topography will often throw much light on the underground structure. The shape of the hills and ridges is necessarily influenced by the inclination of the strata, by the relative hardness of different rock-beds, and by the presence of folds and fissures and other lines of weakness. A quartz vein or bed of hard rock may show itself as a sharp ridge or as a well-defined bench; a stratum of soft rock or the line of a great fissure, or the weakening of the strata by an anticlinal fold, may produce a ravine or a deep valley. The bed of fire-clay under a coal seam, being impervious to water, frequently determines the horizon of numerous springs issuing from the hillsides. As the coal and the associated rocks usually contain pyrites, these springs are often chalybeate. When the location of the deposit has been determined approximately, further search is made by trenches or pits or borings through the surface soil.

Exploratory Work.—Before opening and working a mine it is necessary to have as full and accurate information as possible as to the following:—

1. The probable extent and area of the deposit, its average thickness, and the probable amount and value of the mineral;

2. The distribution of the workable areas of mineral in the deposit;

3. Conditions affecting the cost of opening, developing and working the mine or determining the methods to be adopted.

Work undertaken to secure this information must be distinguished from prospecting, which is the search for mineral deposits and from development, work undertaken to prepare for actual mining operations. Exploratory work is associated intimately both with prospecting and with development, but the purpose is quite distinct from either prospecting, development or working, and it is of importance that this should be clearly recognized. It must be remembered that the line between a workable deposit and one that cannot be profitably worked is often very narrow and that the majority of mineral deposits are not workable. The money that is spent in prospecting and in development is therefore liable to prove a loss. This is a recognized and legitimate business risk, differing only in degree from the risks attending all business operations. The risk of failure in mining enterprises is offset by the chances of more than ordinary profits. If the property proves valuable the returns may be very great. While the risk of loss of capital is not to be avoided, it is of the utmost importance to limit the amount of money expended while the extent and value of the deposit are still uncertain and to do the necessary work by the cheapest methods consistent with thoroughness. As the information as to the character and extent of the deposit becomes more definite, and as the prospects of success become more favourable, money may be spent more freely. The risk will vary with the character of the deposit. In the case of the cheaper and more abundant minerals, such as coal and iron ore, and of large deposits of low-grade ores, the extent and character of the deposit can generally be determined by surface examinations at comparatively small expense. On the other hand, in the case of less regular deposits, including most metalliferous veins, and especially those of the precious metals, the uncertainty is often very great, and it is sometimes necessary to work on a small scale for months before any considerable expenditure of money is justified.

The quickest and cheapest method is by surface explorations. The work of the prospector frequently furnishes much of the information required. By sinking additional pits or by extending the costeaning trenches and uncovering the outcrop of the deposit more fully it is sometimes possible to obtain all the