COAL. WHO can sum up the benefits we derive from coal? It warms and lights our dwellings, cooks our food, illuminates our streets. Coal develops and sustains the force which propels the locomotive along the railway and the ship across the sea; works the printing press, wields the hammer, lifts the weight, draws the load, moves the machinery, grinds the corn, spins the cotton, weaves the cloth, pumps the mine, deepens the river, covers the land with a network of railways, forges the electric wire, and, submerging the ocean telegraph, "will put a girdle round about the Earth in forty minutes." 1 Who shall set bounds to the power of coal, iron, and steam? The economical and industrial importance of the union of coal and iron2 in the British Isles cannot be over-estimated. To the abundance of these minerals in the deposits of the coal formation are owing the increase and prosperity of the British people, their wide-spread mercantile enterprise, their rapid intercourse with all parts of the world, their boundless territories abroad, their opulence and influence at home. From its proximity to a mere patch of the English coal measures—a detached portion not exceeding the area of one of the larger Scottish lakes-Birmingham has risen to the rank of the first iron manufacturing town in the world. Manchester and Glasgow have equally derived their manufacturing and commercial importance from being placed each in the centre of a great coal basin. The vegetable origin of coal is no longer a matter of doubt. The leaves of ferns, reeds, and other plants, are frequently found between layers of shale or slaty clay, beautifully perfect, but converted into coal. And in many kinds of coal, by means of very thin sections, and by the employment of the microscope, the cells of a vegetable structure become visible; thus affording us a distinct proof that coal is really a vegetable substance, and produced by vegetable decay. 3 The coal plants flourished in the widely extended forests of the primeval world; and as they fell and decayed, they left their remains imbedded in sandstone and shales, accumulating in lakes and the deltas and estuaries of rivers, to become transformed into coal in the lapse of ages, by the united influences of heat and pressure. The trunks of the trees, being covered with water, were kept from contact with the air, and gradually decayed, until they were converted into a blackishbrown substance resembling peat, but which still retained more or less of the fibrous structure of wood. The decomposed mass became gradually covered with a deposit of sediment, the great pressure of which, when accumulated into beds of clay or sand of some thickness, gave to this substance the hardness and density of a true mineral. It thus became stored up for future employment in the service of man. The trees which grew in the swamps and forests of the coal period derived their carbonaceous substance from carbonic acid gas and water, existing in the soil and floating in invisible currents in the air. They imbibed the gas by their fronds, leaves, and IDEAL VIEW OF A MARSHY FOREST OF THE COAL PERIOD. roots; and separating the solid carbon from the oxygen gas with which it was combined, they appropriated the former for the purposes of their nourishment and growth, and restored the latter to the atmosphere. But the plant can only decompose carbonic acid and water with the aid of the light and heat of the sun-the process ceases in the dark. In helping the plant to appropriate and deposit carbon in its tissues, the sun parted with so much of its light and heat, which became latent in the vegetable. This long dormant light and heat are set free by the process of combustion. When the Yule' log is laid on the blazing hearth of the baron's hall, and the fagots are piled on the peasant's fire, they shed upon the radiant faces of the festive circle light and heat which were borrowed from the sun, and became latent in the plant, while the seed sprang into a sapling, and at length became a goodly tree, a century or two old. But the coal glowing in the cheerful fires of our town dwellings, and diffusing light by means of the gas-pipes of our streets, is composed of vegetables in which are stored up light and heat derived from the sunshine of distant ages. In the grate we liberate this ancient heat for our comfort; in the gasometer we take advantage of the light for our convenience ; in our boilers and engines we convert the latent heat into mechanical force. 8 "Wood fires," says a distinguished philosopher, “give us heat and light which have been got from the sun a few years ago. Our coal fires and gas lamps bring out, for our present comfort, heat and light of the primeval sun, which have lain dormant beneath seas and mountains for countless ages.' Sketches in Natural History-ELLIS's Chemistry. 'Will put a girdle, &c.- The boast | but the greatest iron mines occur in of Puck, the gentle spirit in Shake- the neighbourhood of the most abunspeare's Midsummer Night's Dream, Act ii., Scene 1. 2 Coal and iron. Not only do the British Isles contain both coal and iron, dant coal measures, and also of the limestone which is so important in its manufacture. The distribution of the coal fields in a country at once indi • La'tent, concealed; inactive. The term here refers to the fact that the power of the sun's rays can be stored up by vegetables for any length of time. When coal is burnt, this stored-up power is developed in the active form of light and heat. 7 Yule log, the large log of wood formerly put on the hearth on Christmas eve, to form the basis of the fire. Yule was the general name for the Christmas festival among the Scandinavians. [Old Norse, jól, the feast.] In Old Eng. Geola was the winter solstice, and the months of December and January were called Fore-Yule and After-Yule respectively. 8 Mechanical force. Thus George Stephenson said that his locomotives were driven by bottled sunbeams. QUESTIONS.-Mention some of the great things done by means of coal. What other mineral is generally found near coal? Mention great cities which owe their importance to coal? What is the origin of coal? How is this proved? How have the coal plants been transformed into coal? Whence did they derive their carbonaceous properties? What are latent or dormant in coal? Whence were they derived? When do they again become active? CHOICE QUOTATIONS. (To be written from memory.) THE CARES OF GREATNESS. PRINCES have but their titles for their glories,— - And, for unfelt imaginations, They often feel a world of restless cares : So that between their titles and low name There's nothing differs but the outward fame. --SHAKESPEARE CONSCIENCE. HE that has light within his own clear breast, |