it obtains its full height. 
In setting the kiln, 
not only in its body, but in the arches also, the 
ends of the bricks touch each other, but narrow 
spaces must be left between the sides of every 
brick for 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. The kiln being filled, the top-course 
is laid with flat bricks, so disposed, that one brick 
covers part of three others, which process is call- 
ed platting. 
The kiln being built, or finished, the firing 
succeeds, and this is the most delicate operation, 
and one that requires practice. The 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 heat as would crack and spoil the low- 
est bricks. To check the burning, the arch-holes 
or mouths are 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 that by its gentle heat it may 
evaporate away the humidity that remains in the 
bricks, and produce drying rather than burning. 
The slow fire requires to be kept up about three 
days and three nights, by occasionally opening 
the vents, to supply 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 found its way through all the chinks 
and openings between the bricks, and begins to 
heat those at the top of the kiln. To ascertain 
the progress of the fire, the top of the kiln must 
| be watched, and as soon as the smoke changes 
colour from a light to a dark hue, the drying is 
complete, and the fire may be urged. The first, 
or white smoke, called waier-smoke, is, in fact, 
little else but the steam of the water while eva- 
porating, 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 must not be white or so strong as to 
melt or vitrify the bricks, and whenever it ap- 
pears to be increasing too rapidly, the vents 
(L 
——— 
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 it is by this 
sinking that 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, are carefully stopped with bricks 
and clay, and in this state it remains until the 
bricks are cold enough to be taken down, when 
they are distributed for use, 
From the nature of the above process it will 
BRICK-MAKING. 
O30 
be evident that bricks of very different qualities 
will be found in the same kiln; for as the fire is 
all applied below, the lower bricks in its imme- 
diate vicinity will be burnt to great hardness, 
or, perhaps, vitrified; those in the middle will 
be well burnt; and those at the top, which are 
not only most distant from the fire, but exposed 
to the open air, will be merely baked, and not 
burnt at all; consequently, if they can be used, 
they must be reserved for inside work, that is 
not exposed to weather, or they will soon fail 
and crumble to pieces. 
In 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 
are only intended to contain brushwood to pro- 
duce the first kindling, and not for the future 
supply of fuel. No fuel is used except the breeze 
cinders and small coal before described, and this 
is distributed by means of a sieve, with wires 
about half an inch apart, over every course as it 
is laid near the bottom, and over every alternate 
course, or every third course higher up in the 
kiln. 
they diminish as they ascend, because the action 
of the heat is to ascend, consequently there is | 
not the same necessity for fuel in the upper, as 
in the lower part of the kiln. The brushwood 
in the bottom ignites the lower stratum of fuel, | 
and from the nature of its distribution, the ver- 
tical as well as horizontal joints will be filled 
with 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 therefore much more generally distributed 
throughout the whole mass, and in order to con- 
fine it, the entire outside of the clamp is thickly 
plastered with wet clay and sand, the bottom 
holes being opened or shut as occasion may re- 
quire for regulating the draught of air. Not- 
withstanding the heat is much more equably dis- 
tributed throughout this form of kiln, yet the 
outside bricks all around receive very little ad- 
vantage from the fire, and are never burnt; but 
being on the outside they are easily removed, | 
and are reserved for the outside casing of the | 
next clamp that may be built; and being then 
turned with their unbaked sides inwards, some 
of them become available. 
their perfection and goodness. 
burnt very hard but have not lost their figure or 
shape, are called ma/ms, or malm-facings, or 
malm-paviors, and are used for facing good work; 
or for paving, for which their hardness makes | 
them peculiarly suitable. The main body of the 
clamp produces well burnt and regularly formed | 
bricks called stocks, with which the generality of | 
houses are built; and such as are imperfectly 
burnt, and are soft, are called place bricks. These 
The first layers of this fuel are from an | 
inch to an inch and a half in thickness; but | 
On taking down the || - 
clamp, the bricks are assorted, in London, into — 
three separate parcels or varieties, according to | 
Those that are | 
