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&c. he constructs at pleasure, with the addition of the peculiar parts, working models of almost every kind of machine. These he puts in motion by a water wheel, or a steam engine, in such a way as to make them in general do the actual work of the real machines, on a small scale; and he explains at the same time the chemical and philosophical principles, on which the various processes of the arts exhibited depend—In the course of his lectures, he explains the theory and practice of mining, and of smelting metallic ores; of bringing them to nature; of converting, purifying, compounding, and separating the metals; and the numerous and various manufactures which depend upon them, as well as the arts which are remotely connected with them, such as Etching and Engraving. He exhibits the method of obtaining Coal and other minerals, the processes by which sulphur, alum, common salt, acids, alkalies, nitre, and other saline substances are obtained, and in which they are used, the mechanical process in the formation of gunpowder, as well as its theory and effects—He shews the arts of procuring and working animal and vegetable substances; the great staple manufactures of the country, in wool, cotton,
