Discoveries and Inventions of the Nineteenth Century

The foregoing pages have been devoted to the description of inventions or operations in which mechanical actions are the most obvious features. Some of the contrivances described have for their end and object the communication of motion to certain bodies, others the arrangement of materials in some definite form, and all are essentially associated with the idea of what is called matter. But we are now about to enter on another region—a region of marvels where all is enchanted ground—a region in which we seem to leave far behind us our grosser conceptions of matter, and to attain to a sphere of more refined and subtile existence. For we 381are about to show some results of those beautiful investigations in which modern science has penetrated the secrets of Nature by unfolding the laws of light— “Light Ethereal, first of things, quintessence pure.” The diversity and magnificence of the spectacles which, by day as well as by night, are revealed to us by the agency of light, have been the theme of the poet in every age and in every country. It cannot fail to arrest the attention to find Science declaring that all the loveliness of the landscape, the fresh green tints of early summer and the golden glow of autumn, the brilliant dyes of flowers, of insects, of birds, the soft blue of the cloudless sky, the rosy hues of sunset and of dawn, the chromatic splendour of rubies, emeralds, and other gems, the beauties of the million-coloured rainbow,—are all due to light—to light alone, and are not qualities of the bodies themselves, which merely seem to possess the colours. The following quaint stanzas, in which a poet of the seventeenth century addresses “Light” have a literal correspondence with scientific truth: “All the world’s bravery, that delights our eyes, Is but thy several liveries; Thou the rich dye on them bestowest, Thy nimble pencil paints this landscape as thou goest. “A crimson garment in the rose thou wearest:; A crown of studded gold thou bearest; The virgin lilies, in their white, Are clad but with the lawn of almost naked light. “The violet, Spring’s little infant, stands Girt in thy purple swaddling-bands; On the fair tulip thou dost dote; Thou clothest it in a gay and parti-coloured coat.” All these beauties are indeed derived from the imponderable and invisible agent, light; and the variety and changefulness of the effects we may constantly observe show that light possesses the power of impressing our visual organs in a thousand different ways, modified by the surrounding circumstances, as witness that ever-shifting transformation scene—the sky. In the skies of such a climate as that of England there are ceaseless changes and ever-beautiful effects, producing everywhere more perfect and diversified pictures than the richest galleries can show. In the night how changed is the spectacle, when the sun’s more powerful rays are succeeded by the soft light of the moon, sailing through the azure star-bestudded vault! What limitless scope for the artist is afforded by these innumerable modifications of a single subtile agent, in light and shade, brightness and obscurity, in the contrasts and harmonies of colours, and in the countless hues resulting from their mixtures and blendings! It will be necessary, before attempting to explain the discoveries and inventions which prove how successfully science, aided by the powerful mathematical analysis of modern times, has acquired a knowledge of the ways of light, to discuss such of the ordinary phenomena as have a direct bearing upon the subjects to be considered. 382 Fig. 189.—Rays.