400 



!<' A R Al E R S ' II V: ii I S 1' E K 



[No. 7 



appeaiance shown in Fig. 120, which is an end 

 view ol" it. And this is permanent work, or work 

 that remains in the kihis that have fire-places huili 

 ill their floors, or has to he formed every lime the 

 kihi is set, when it has a Hat boiloin. Tiie inter- 

 vals hi'tween the walls are laid first witli shavin<fs, 

 or light and dry brushwood, or any thing that vvili 

 kindle easily, then with larger brushwood cut into 

 short lengths, that it may pack in a compact man- 

 ner ; and, lastly, with logs of split Ihckory, or 

 strong burning wood. This done, the over-span- 

 ning or formation of the arches is conuiienced ; lor 

 this purpose every course of bricks is made lo ex- 

 tend an inch and a half beyond the course imme- 

 diately below it, for five courses in height, taking 

 care to skintle well behind, that is, to hack up, or 

 fill up with bricks against the over-spanners. An 

 equal number of courses, on the opposite side ol' 

 the arch, is then set as before, and thus the arch 

 is formed, which is called rounding, and is a nic, 

 and imjjortant operation, for if the arch fails or ialls 

 in, the (ire may be extinguished, or many of the 

 bricks above the arch may be broken. Tiie inter- 

 mediate spaces between the arches are now filled 

 up, so as to bring the whole surli^ce lo a level, and 

 then the setting of the kiln proceeds with regulari- 

 ty until it obtains its full height. In setting the 

 kiln, not only in its body, but in the arclies also, 

 the ends of the bricks touch each other, but nar- 

 row sjiaces must be left between the sides of every 

 brick lor the fire to play through, and this is done 

 by placing the bricks on their edges, and following 

 what is called the rule of three upon three, by 

 brickmakers, reversing the direction of each course 

 as shown at Ficc. 121. The kiln being filled, the 

 top course is laid with flat bricks, so disposed, that 

 one brick covers part of three others, which pro- 

 cess is called platting. 



The kilns of Philadelphia are constructed and 

 managed in a manner very nearly according with 

 the above description of the country kilns of Eng- 

 land, but they are larger, having an average vvidtli 

 of twenty-eight feet in the clear, and are higher; 

 but the bricks are not laid more than thirty-five or 

 thirty-six courses. There are seven arches or 

 firing holes in the end, each two feet high by six- 

 teen inches wide, and the distance between each 

 arch is three bricks. Such a kiln holds 140,000 

 bricks, and consumes from foity to fifiy cords of 

 wood for burning them. 



The kiln being built, or finished, the firing suc- 

 ceeds; and this is the most delicate operation, and 

 one that requires practice. "^iMie fuel is kindled 

 under the arches, but requires close watching and 

 attendance, for being in a large body, it would 

 burn violently and produce so sudden a iieat as 

 would crack and spoil the lowest bricks. To check 

 the burning, the arch holes or mouths arc closed 

 with dry bricks, or even smeared with wet clay, 

 in order to prevent the entrance of air, and rapid 

 combustion that would ensue. The fire must be 

 made to smother rather than burn, in order ihal 

 by its gentle heat it may evaporate away the hu- 

 midity that remains in the bricks, and produce dry- 

 ing rather than burning. The slow fire requires 

 lo be kept up about three days and three nights, 

 by occasionally opening the vents, to sup|»ly air 

 and additional fuel, and closing or partially closing 

 them, until the fire gets up, as the workmen call 

 It, that is to say, until it has Ibund its way through 

 all the chinks and openings between the bricks. 



and begins lo heat those at the top of the kiln. 

 To ascertain the progress of the fire, the top of the 

 kiln nmst be watched, and as soon as the smoke 

 clianijies color liom a light to a dark hue, the dry- 

 ing is complete, and the fire may be urged. The 

 first, or white smoke, called water-smoke, is, in 

 liict, little else but the steam of the water while 

 evaporating, and when that is gone, the real smoke 

 of the fuel succeeds, and now the vents may be 

 opened to admit full draught, and a strong fire kept 

 up for from forty-eight to sixty hours ; but the 

 heat musi not be white or so strong as to melt 

 or vitrily the i)ricks, and whenever it appears to be 

 increasing too rapidly, ihe vents must be partially 

 closed. By this time the kiln, if it contains thirty- 

 five courses, will be found to have sunk about nine 

 inches ; but the stronger the clay the more it will 

 shrink, and ii is by this sinking thai the workman 

 knows when the kiln is sufficiently burnt. The 

 experience of burning a few kilns will show how 

 much the clay of that particular place yields to the 

 firing. When it is thus ascertained that the kiln 

 is done, the vent-holes, and all other chinks through 

 which air can enter, arc carefully stopped with 

 bricks and clay, and in this state it remains until 

 the bricks arc cold enough to be taken down, when 

 they are distributed for use. 



From the nature of the above process it will be 

 evident that bricks of very different qualities will 

 be found in the same kiln ; ihr as the fire is all ap- 

 plied below, the lower bricks in its immediate vi- 

 cinity will be burnt lo great hardness, or, perhaps, 

 vitrified ; those in the middle will be well burnt ; 

 and those at the top, which are not only most dis- 

 tant from the fire, but exposed to the open air, 

 will be merely baked, and not burnt ai all ; con- 

 sequently, if they can be used, they must be re- 

 served for inside work, that is not exposed to 

 weather, or they will soon fail and crumble to 

 pieces. 



(n the London method of open clamp burning, 

 without any kiln, the piling and disposition of the 

 bricks is the same as above described, except that 

 the bottom arches are much smaller, as they arc 

 only intended to contain brushwood to produce 

 the first kindling, and not for the future supply of 

 fuel. No fuel is used except the breeze cinders 

 and small coal belbre described, and this is distri- 

 buted by means of a sieve, witli wires about half 

 an inch apart, over every course as it is latd near 

 the bottom, and over every other alternate course, 

 or every third course higlver up in tlie kiln. The 

 first layers of this fuel are from an inch to an inch 

 and a half in thickness ; but they diminish as they 

 ascend, because the action of the heat is to ascend, 

 consequently thc-e is not the same necessity lor 

 fuel in the upper, as in the lower part of the kiln. 

 The brushwood in the bottom ignites the lower 

 stratum of fuel, and fiom the nature of its distri- 

 bution, the vertical as well as horizontal joints 

 will be filled willi it, and thus the fire gradually 

 spreads itself upwards, and the whole clamp is 

 nothing but a mass of bricks and burning fuel. 

 The heat is therelbie much more generally distri- 

 buted throughout the whole mass, and in order lo 

 confine it, the cmire outside of the clam|) is thickly 

 plastered with wet clay and sand, the bottom lioles 

 being o|)ened or shut as occasion may require for 

 regulating the draught of air. 



Notwithstanding the heat is much more equably 

 distributed throughout tliis Ibrm of kiln, yet the 



