a furnace of one or two pots not exceeding fifty pounds each, kept working for that sole purpose. In the ordinary course of Flint Glass manufacture, working a large pot of Glass for optical purposes not only retards general operations, but usually spoils the greatest part of its contents, whilst the quantity of optic plate produced is comparatively small, and uncertain in its results; and if unfit for the optician, it becomes valueless to the manufacturer for other purposes. As an affair of science and merit, especially were a Government premium offered for an uniformly certain process, which has not yet been accomplished at home or abroad, it is anticipated that English manufacturers would rival foreigners in this field of honourable competition. The author has constructed a small furnace, to try the principle of agitating fused Flint Glass by a rotating pot, with one or more interior divisions: and this means of subjecting the Glass to an uniform intensity of caloric and agitation in a covered pot destroys the striæ or cords by mechanical means, without exposing the contents to the cooling effects of the atmospheric air.

Flint Glass works require a very considerable area of ground—viz., about half an acre or more—to conduct the various operations; and separate apartments are requisite for washing sand, refining alkali, and picking and washing broken glass, technically called cullet; besides mixing-rooms, &c., there are, likewise, requisite one or two furnaces, usually with ten melting pots in each; a horse or steam mill, for grinding old crucibles or pots; from two to four arches, with their fire-places, for annealing Glass; and large rooms, or lofts, in which to mix clay for making pots and crucibles; besides store-rooms and a packing warehouse. The whole should be so planned, that the crude materials in the course of