POTTERY 611 



B, fig. 1646, is the plan at the level d, d, of the floor, to show the arrangement 

 and distribution of all the horizontal flues, both circular and radiating. 



c, fig. 1647, is a plan at the level e, e, of the upper ^_- 



mouths b, of the furnaces, to show the disposition of the 

 fireplaces of the vertical flues, and of the horizontal 

 registers, or peep-holes. 



D, Jig. 1647, is a bird's-eye view of the top of the 

 vault or dome s, to show the disposition of the vent- 

 holes, c, c. 



v,fig. 1648, is a detailed plan at the level c, c, of one 

 furnace and its dependencies. 



F, Jiff. 1649, is a transverse section, in detail, of one 

 furnace and its dependencies. 



The same letters indicate the same objects in all the figures. 



Charging of the kiln. The saggers are piled up first in the space between each of 

 the upright furnaces, till they rise to the top of the flues. These contain the smaller 

 articles. Above this level large fire-tiles are laid, for supporting other saggers, filled 

 with teacups, sugar-basins, &c. In the bottom part of the pile, within the preceding, 

 the same sorts of articles are put ; but in the upper part all sueh articles are placed 

 as require a high heat. Four piles of small saggers, with a middle one 10 inches in 

 height, complete the charge. As there are 6 piles between each furnace, and as the 

 biscuit-kiln has 8 furnaces, a charge consequently amounts to 48 or 50 bungs, each 

 composed of from 18 to 19 saggers. The inclination of the bungs ought always to 

 follow the form of the kiln, and should therefore tend towards the centre, lest the 

 strong draught of the furnaces should make the saggers fall against the walls of the 

 kiln, an accident apt to happen were these piles perpendicular. The last sagger of 

 each bung is covered with an unbaked one, three inches deep, in place of a round lid. 

 The watches are small cups, of the same biscuit as the charge, pkiced in saggers, four 

 in number, above the level of the flue-tops. They are taken hastily out of the saggers, 

 lest they should get smoked, and are thrown into cold water. 



When the charging is completed, the firing is commenced, with coal of the best 

 quality. The management of the furnaces is a matter of great consequence to the 

 success of the process. No greater heat should be employed for some time than may 

 be necessary to agglutinate the particles which enter into the composition of the paste, 

 by evaporating all the humidity ; and the heat should never be raised so high as to 

 endanger the fusion of the ware, which would make it very brittle. 



Whenever the mouth or door of the kiln is built up, a child prepares several fires in 

 the neighbourhood of the howell, while a labourer transports in a wheelbarrow a supply 

 of coals, and introduces into each furnace a number of lumps. These lumps divide 

 the furnace into two parts ; those for the upper flues being placed above, and those 

 for the ground flues below, which must be kept unobstructed. 



The fire-mouths being charged, they are kindled to begin the baking, the regulator 

 tile, z, fig. 1649, being now opened ; an hour afterwards the bricks at the bottom of 

 the furnace are stopped up. The fire is usually kindled at 6 o'clock in the evening, 

 and progressively increased till 10, when it begins to gain force, and the flame rises 

 half-way up the chimney. The second charge is put in at 8 o'clock, and the mouths 

 of the furnaces are then covered with tiles ; by which time the flame issues through 

 the vent of the tower. An hour afterwards a fresh charge is made ; the tiles s, which 

 cover the furnaces, are slipped back ; the cinders are drawn to the front, and replaced 

 with small coal. About half -past 11 o'clock the kiln-man examines his furnaces, to 

 see that their draught is properly regulated. An hour afterwards a new charge of 

 coal is applied ; a practice repeated hourly till 6 o'clock in the morning. At this 

 moment he takes out his first watch, to see how the baking goes on. It should be at 

 a very pale-red heat ; but the watch of 7 o'clock should be a deeper red. He removes 

 the tiles from those furnaces which appear to have been burning too strongly, or 

 whose flame issues by the orifices made in the shoulder of the kiln ; and puts tiles 

 upon those which are not hot enough. The flames glide along briskly in a regular 

 manner. At this period he draws out the watches every quarter of an hour, and 

 compares them with those reserved from a previous standard kiln ; and if he observes 

 a similarity of appearance, he allows the furnaces to burn a little longer ; then opens 

 the mouths carefully and by slow degrees ; so as to lower the heat and finish the 

 round. 



The baking usually lasts from 40 to 42 hours ; in which time the biscuit-kiln may 

 consume 14 tons of coals ; of which four are put in the first day, seven the next day 

 and following night, and the last four give the strong finishing heat. 



Emptying the kiln. The kiln is allowed to cool very slowly. On taking the ware 

 out of the saggers, the biscuit is not subjected to friction, as in the foreign potteries, 



B R2 



