On Brick-making. 
383 
1830 .] 
jnuch silica, renders them difficult to mould, and increases the danger of their nitri- 
fying, and adhering together in the kiln. The proportion may, however, vary con- 
siderably ; and the best mode of ascertaining the fitness of .any clay, is to make 
a few bricks, and bake them in a small kiln or oven. . . 
Having ascertained the earth to be of a suitable nature, the prepaiation of it 
will occupy, from November to January. # 
The upper surface of the ground is first removed, if it consists of vegetable 
soil unadapted to the purpose : a trench is then dug from 3 to 5 feet in width, 
and about the same in depth : the earth of excavation is heaped along the 
edge of the trench close alongside, a second trench is dug, the clay from 
which is thrown into the first trench, and so on, for a convenient space, talcing 
care to leave the clay in loose lumps, that it may be permeable to water and frost : 
unless this precaution be taken, of leaving the crude clay exposed during the 
winter, the bricks will be apt to split and break in drying ; especially if the clay 
be of a rich quality. 
Towards April or May, the work is resumed in the following manner 
A labourer, called in French the demileur, throws several buckets of water into 
the last cut trench, which has remained empty, against the heap of clods ; lie 
breaks these up with the spade, and piles them in layers in a circle around him, o 
10 feet diameter, watering the layers until they have reached a height of If toot : 
— he then works the mixture with his feet, and with a hoe, draws it to the cen le, 
removes all stony particles, replaces it in heaps, smooths the surface, and some- 
times even covers it with straw, to prevent the drying action of the air. 
It is convenient to have a trough of water hard by, to clean the tools used ; also 
a small wooden scraper. , . . , , 
Each heap should contain clay enough for 2,000 bricks, or about a cube of 
^9 ifciifc 
~A portion of the clay is now conveyed in barrows to the table of the moulder, 
who is provided with several wooden brick-moulds, and ustribe, or flat lath, to 
pass over the surface of the moulds.— On the table should also be placed a small 
trough of water, to hold the stribe, a small knife to clean the mou Ids, and a sup- 
ply of dry sand. The French bricks are commonly 9 inches long, 4 4 broad, and 
thick, and they contract a tenth in drying. . , , 
The barrow-man, and his assistant, place upon the table, previously sanded, a 
quantity of clay sufficient for 200 bricks. . 
A boy dips one of the moulds first m water, and immediately after, into the 
dry sand, and hands it to the moulder, who fills it with clay, squares it, slides 
it to the edge of the table, and hands it, held sideways, lo an assistant, who 
carries it to the drying ground, suddenly turns it, and raises the mould perpendi- 
cularly, so as not to deform the brick. Proceeding m this way, the moulder 
ought to make from 6 to 9,000 bricks per diem, if the clay be very soft ; but it is 
better to use a harder material, though the produce be reduced thereby to 2 
° r The°drving -round should be well levelled and sprinkled with sand ; it should 
be prov1dld g wfth drains in case of rainy weather. The bricks remain on their 
L sTdes for about 24 hours, when, if sufficiently solid, they are set on edge, 
and when capable of bearing it, they are stacked with interstices, to admit a 
circulation of air throughout. Should rain be expected, the stacks should be 
protected with thatch. About 20 days will be required to dry the bricks fit for 
kl We" now come to the operation of kilning, which requires some nicety as the 
heat at which a brick will be well baked, falls little short of that which will 
vitrify and spoil it for purposes of building with moi tai cement 
Kilns of peculiar construction, are required for burning bricks with wood ; but 
where ioal fs used, nothing further is required but to build up a solid pile, with 
“'X a 1rst ye polnt l !'s‘to feveUhe' ground, lay one or two courses of waste bricks, as 
a substratum^ and entrench the whole with a oT&iclsTbe burned at a 
time’ 6 The; 6 'larger and bighe? ttekilnrtie less fuel will he used in proportion. At 
SE Z? sometimes c A 
always^Tlie most 'evenljMiaked, and the Flemish Engineers make a point of rejecting 
the M.° ckreTrutofte length and breadth of the parallelogram in the ratio of 
