usually made from two parts of ground potsherd, (the glass being carefully chipped off,) and one part of new clay, kneaded by the feet, &c. Occasionally, the siege, or bottom of the furnace, is repaired, and a new crown (E), or the greater part of the crown, renewed, without extinguishing the furnace.

In case of accident, which is not unfrequent, as the falling in of part of the arch, or crown of the furnace, the tiseur must throw upon the bars as much fuel as possible from the teaze-hole, and then, through the breach in the crown, fill the entire furnace with a solid mass of coals and cinders; the upper part of which forms a centre upon which to build a new crown, or arch. The draught is thus almost stopped, and but little consumption of coal takes place, while the workmen are proceeding with the new arch, under the inconvenience of the smoke and heat of the furnace. The pots remain partly or wholly full of metal. When this is completed, the furnace is gradually urged to a maximum of heat, and the debris is taken out by degrees into the cave beneath, by removing a bar or two. In the course of twelve hours, by means of prepared arch-bricks, and Stourbridge clay as mortar or cement, the repair of a fearful accident in the midst of the blowing operations has been completed by the workmen; and that without materially, if at all, diminishing the weight of the week's work of manufactured Glass.

Round furnaces are most economical, and almost exclusively used for Flint Glass works. Economy of fuel greatly depends upon the size and properties of the furnace; too large dimensions leave too great an area unoccupied by the pots or the fuel; and too small a furnace exposes the backs of the pots, (which are placed round the exterior diameter of the