of time, gets its maximum heat, it usually forms sufficient clinkers from the coals; the potsherds are then no longer needed.

Dimensions of a furnace for ten pots, of thirty-six inches diameter—viz., twelve feet seven inches inside diameter of the siege; nineteen feet outside diameter; including the flues; four feet six in height to the inside centre of the dome (D), each of the arches (E), being three feet one inch wide, by three feet three and a half inches to the highest part.

A Flint Glass furnace is reverberatory; and as no heat or flame is usually allowed to issue from the centre, it therefore seeks escapement through the linnet holes (C), below the foot of the dome, and passes up the flues (F), viz., one between each of the ten pots placed around the siege, discharging the smoke, &c., into the outer brick dome, as shown in page 56, and from thence through the funnel and chimney-shaft. The duration of a furnace is scarcely ever less than three years, and often exceeds ten years, according to the quality of the Stourbridge clay bricks: some of these weigh nearly half a ton; they are