A great many centuries afterward--that is to say, toward the close of the fifteenth century of the Christian era--when some of the secrets of the glass-house, supposed to have been known to the ancients, were lost, and the simple art of blowing glass was but scantily cultivated--an artificer, whose name has unfortunately escaped immortality, while employed over his crucible accidentally spilt some of the material he was melting. Being in a fluid state it ran over the ground till it found its way under one of the large flag-stones with which the place was paved, and the poor man was obliged to take up the stone to recover his glass. By this time it had grown cold, and to his infinite surprise he saw that, from the flatness and equality of the surface beneath the stone, it had taken the form of a slab--a form which could not be produced by any process of blowing then in use. Such was the accident that led to the discovery of the art of casting PLATE-GLASS. These are the only _accidents_ recorded in the History of Glass. For the rest--the discovery of its endless capabilities and applications--we are indebted to accumulated observation and persevering experiment, which, prosecuting their ingenious art-labors up to the present hour, promise still farther to enlarge the domain of the Beautiful and the Useful. The importance of glass, and the infinite variety of objects to which it is applicable, can not be exaggerated. Indeed it would be extremely difficult to enumerate its properties, or to estimate adequately its value. This thin, transparent substance, so light and fragile, is one of the most essential ministers of science and philosophy, and enters so minutely into the concerns of life, that it has become indispensable to the daily routine of our business, our wants, and our pleasures. It admits the sun and excludes the wind, answering the double purpose of transmitting light and preserving warmth; it carries the eyes of the astronomer to the remotest region of space; through the lenses of the microscope it develops new worlds of vitality which, without its help, must have been but imperfectly known; it renews the sight of the old, and assists the curiosity of the young; it empowers the mariner to descry distant ships, and to trace far-off shores, the watchman on the cliff to detect the operations of hostile fleets and midnight contrabandists, and the lounger in the opera to make the tour of the circles from his stall; it preserves the light of the beacon from the rush of the tempest, and softens the flame of the lamps upon our tables; it supplies the revel with those charming vessels in whose bright depths we enjoy the color as well as the flavor of our wine; it protects the dial whose movements it reveals; it enables the student to penetrate the wonders of nature, and the beauty to survey the marvels of her person; it reflects, magnifies, and diminishes; as a medium of light and