_The Unknown_.--I will readily allow that accident has had much to do with the origin of the arts as with the progress of the sciences. But it has been by scientific processes and experiments that these accidental results have been rendered really applicable to the purposes of common life. Besides, it requires a certain degree of knowledge and scientific combination to understand and seize upon the facts which have originated in accident. It is certain that in all fires alkaline substances and sand are fused together, and clay hardened; yet for ages after this discovery of fire, glass and porcelain were unknown till some men of genius profited by scientific combination often observed but never applied. It suits the indolence of those minds which never attempt anything, and which probably if they did attempt anything would not succeed, to refer to accident that which belongs to genius. It is sometimes said by such persons, that the discovery of the law of gravitation was owing to accident: and a ridiculous story is told of the falling of an apple as the cause of this discovery. As well might the invention of fluxions or the architectural wonders of the dome of St. Peter's, or the miracles of art the St. John of Raphael or the Apollo Belvidere, be supposed to be owing to accidental combinations. In the progress of an art, from its rudest to its more perfect state, the whole process depends upon experiments. Science is in fact nothing more than the refinement of common sense making use of facts already known to acquire new facts. Clays which are yellow are known to burn red; calcareous earth renders flint fusible--the persons who have improved earthenware made their selections accordingly. Iron was discovered at least one thousand years before it was rendered malleable; and from what Herodotus says of this discovery, there can be little doubt that it was developed by a scientific worker in metals. Vitruvius tells us that the ceruleum, a colour made of copper, which exists in perfection in all the old paintings of the Greeks and Romans and on the mummies of the Egyptians, was discovered by an Egyptian king; there is therefore every reason to believe that it was not the result of accidental combination, but of experiments made for producing or improving colours. Amongst the ancient philosophers, many discoveries are attributed to Democritus and Anaxagoras; and, connected with chemical arts, the narrative of the inventions of Archimedes alone, by Plutarch, would seem to show how great is the effect of science in creating power. In modern times, the refining of sugar, the preparation of nitre, the manufacturing of acids, salts, &c., are all results of pure chemistry. Take gunpowder as a specimen; no person but a man infinitely diversifying his processes and guided by analogy could have made such a discovery. Look into the books of the alchemists, and some idea may be formed of the effects of experiments.