These sheds or "hallettes" are about 12 feet broad, the posts are 5 feet high, but the length is variable. To strengthen them against the wind, solid stakes are driven into the ground and nailed to the uprights, which, to avoid the dampness of the soil, rest upon baked bricks. In consequence of their lightness, these sheds are easily taken to pieces, and are moved as the work advances; the brick-maker should choose a convenient position, so that they may be used as long as possible. To obtain satisfactory drying the space between two sheds should not be less than 10 metres, so that air and light may have free access.
1 The mailing consists of strong straw plaited together, and about two yards in length It is attached above and below by two little switches arranged lengthways. Instead of straw matting, movable squares of wood of about thirty inches in height are sometimes used, and placed vertically against the bricks; over these, movable wooden roofs art-placed which take the place of matting. In this case the hack is neither very high no very broad, and the bricks are completely enclosed.
In the latter case, however, special precautions are advisable: we must avoid the action of the sun, which dries the bricks too quickly and warps them. Certain clays cannot bear drying in the open air, but require closed drying-places in which even currents of air must be avoided. Under a shed such as we have just described, they begin by stacking two "feutlles" in the middle, and when the foot is quite dry, a third and a fourth are placed, one on each side, which dry in their turn; then another is placed, and so on. Only one row must be placed at a time, for any brick enclosed when fresh between other bricks, remains fresh and does not dry.
Fig. 173. Transverse Section.
Fig. 174. Elevation with and without Planks.
(Scale of 1 centimetre to the metre).
The thickness of the hack is as much as 14 to 16 "feuilles," the height at the centre is from 18 to 22 layers, that is to say, about 8 feet; but the other "feuilles" are not so high on account of the slope of the roofing. The bays are 4 yards long, that is to say, about 50 bricks placed side by side with an interval of about a finger's thickness between them.
A shed 60 yards long (15 bays) can therefore shelter 230,000 bricks. But such a number is rarely allowed to accumulate, because for the requirements of manufacture room must be made from time to time, and the shed relieved of the dry bricks under its shelter.
In order to guard the bricks from the rain which might be driven by the wind under the shed, matting or brushwood is used and is laid against the foot of the "feuilles," when the weather is uncertain. But this precaution is only necessary when the hack is quite close to the side of the shed.
As deal of the usual trade dimensions is used, it is easy, knowing the price of the wood, to make an estimate of the cost of a shed (see p. 18 2).
We have said that the preceding arrangement allows of the drying of machine-made bricks, but in this case, to avoid the too rapid action of the sun, it is advisable to place together a certain number of sheds, which thus form one single open surface (Fig. 175). One side of the covering is formed of Venetian shutters, which enable a draught to pass from the lower to the upper part of the shed. For this part of the covering a direction least exposed to rain will be chosen. The other part is made of tiles or, more cheaply, of planks as in ordinary sheds; for the use of tiles almost triples the cost. A covering of tarred wood lasts twenty years or even longer, as we have observed in many cases.
Fig. 175. Section of several Combined "Hallettes." (Scale, 16 millimetres to the metre).
As economy is required in this class of construction, a simple zinc gutter 6 or 7 inches broad is used and fixed by hooks, and, to be ready for an always possible accident, the part between the uprights is reserved for a tramway or the passing of barrows.
To avoid waste, the wood used should be of the usual trade dimensions, which, as we know, are measured in units of 33 centimetres (about 1 foot). For the estimate of such a shed, we refer the reader to p. 183.