Some clay rocks which have been laid down by water are very uniform through their whole thickness, and are called mud-stones. Others split readily into fine leaflets or laminae parallel to their bedding, and this structure is accentuated by the presence of films of other materials, such as sand or vegetable debris. Laminated clays of this sort are generally known as shales; they occur in many formations but are very common in the Carboniferous. Some of them contain much organic debris, and when distilled yield paraffin oil, wax, compounds of ammonia, &c. In these oil-shales there are clear, globular, yellow bodies which seem to be resinous. It has been suggested that the admixture of large quantities of decomposed fresh-water algae among the original mud is the origin of the paraffins. In New South Wales, Scotland and several parts of America such oil-shales are worked on a commercial scale. Many shales contain great numbers of ovoid or rounded septarian nodules of clay ironstone. Others are rich in pyrites, which, on oxidation, produces sulphuric acid; this attacks the aluminous silicates of the clay and forms aluminium sulphate (alum shales). The lias shales of Whitby contain blocks of semi-mineralized wood, or jet, which is black with a resinous lustre, and a fibrous structure. The laminated structure of shales, though partly due to successive very thin sheets of deposit, is certainly dependent also on the vertical pressure exerted by masses of super-incumbent rock; it indicates a transition to the fissile character of clay slates.
(J. S. F.)
CLAY CROSS, an urban district in the Chesterfield parliamentary division of Derbyshire, England, near the river Amber, on the Midland railway, 5 m. S. of Chesterfield. Pop. (1901) 8358. The Clay Cross Colliery and Ironworks Company, whose mines were for a time leased by George Stephenson, employ a great number of hands.
CLAYMORE (from the Gaelic claidheamh mòr, “great sword”), the old two-edged broadsword with cross hilt, of which the guards were usually turned down, used by the Highlanders of Scotland. The name is also wrongly applied to the single-edged basket-hilted sword adopted in the 16th century and still worn as the full-dress sword in the Highland regiments of the British army.
CLAYS, PAUL JEAN (1819-1900), Belgian artist, was born at Bruges in 1819, and died at Brussels in 1900. He was one of the most esteemed marine painters of his time, and early in his career he substituted a sincere study of nature for the extravagant and artificial conventionality of most of his predecessors. When he began to paint, the sea was considered by continental artists as worth representing only under its most tempestuous aspects. Artists cared only for the stirring drama of storm and wreck, and they clung still to the old-world tradition of the romantic school. Clays was the first to appreciate the beauty of calm waters reflecting the slow procession of clouds, the glories of sunset illuminating the sails of ships or gilding the tarred sides of heavy fishing-boats. He painted the peaceful life of rivers, the poetry of wide estuaries, the regulated stir of roadsteads and ports. And while he thus broke away from old traditions he also threw off the trammels imposed on him by his master, the marine painter Theodore Gudin (1802-1880). Endeavouring only to give truthful expression to the nature that delighted his eyes, he sought to render the limpid salt atmosphere, the weight of waters, the transparence of moist horizons, the gem-like sparkle of the sky. A Fleming in his feeling for colour, he set his palette with clean strong hues, and their powerful harmonies were in striking contrast with the rusty, smoky tones then in favour. If he was not a “luminist” in the modern use of the word, he deserves at any rate to be classed with the founders of the modern naturalistic school. This conscientious and healthy interpretation, to which the artist remained faithful, without any important change, to the end of an unusually long and laborious career, attracted those minds which aspired to be bold, and won over those which were moderate. Clays soon took his place among the most famous Belgian painters of his generation, and his pictures, sold at high prices, are to be seen in most public and private galleries. We may mention, among others, “The Beach at Ault,” “Boats in a Dutch Port,” and “Dutch Boats in the Flushing Roads,” the last in the National Gallery, London. In the Brussels gallery are “The Port of Antwerp,” “Coast near Ostend,” and a “Calm on the Scheldt”; in the Antwerp museum, “The Meuse at Dordrecht”; in the Pinakothek at Munich, “The Open North Sea”; in the Metropolitan Museum of Fine Arts, New York, “The Festival of the Freedom of the Scheldt at Antwerp in 1863”; in the palace of the king of the Belgians, “Arrival of Queen Victoria at Ostend in 1857”; in the Bruges academy, “Port of Feirugudo, Portugal.” Clays was a member of several Academies, Belgian and foreign, and of the Order of Leopold, the Legion of Honour, &c.
See Camille Lemonnier, Histoire des Beaux-Arts (Brussels, 1887).
(O. M.*)