This includes the extraction of the clay and its transport to the place where it is to be manufactured. Arrangements for working differ according as the pits are open or underground.

I. Open-Air Pits

Extraction

In the majority of brickworks using the plateau-slime, this extraction is of the most simple character.

Fig. 7. Workings of Plastic Clay at Arcueil.

If hand-machines are used like those in the neighbourhood of Paris (Fig. 89), they are placed near the beds of clay. With a special tool, resembling a wheelwright's spokeshave but with a blade higher and more curved, the workman cuts the earth in tiers, the earth when cut falling to the foot of the machine; it is used as it is, with a little moistening if too dry. When the distance between the bed of clay and the machine becomes too great, that is to say every week or fortnight, the latter is brought nearer. When the bricks are hand-moulded (Flemish method) the clay is extracted beforehand, in order that it may undergo weathering. If ordinary brick-earth (lehm) is used, the shovel and pick are sufficient; if rich clays, however, are used, the process is as follows: -

Fig. 8. Workings of Plastic Clay at Arcueil.

The bed is opened by removing the vegetable earth or any other layer likely to injure the working. Sometimes these layers are fairly thick and entail somewhat heavy expense, and it is necessary in that case that the thickness of the bed should be great enough to repay this outlay. The bed is attacked in tiers (Figs. 7 and 8); the clay is extracted by means of two special tools, kinds of pointed hoe with edged sides; one with a short handle, the other with a longer one. With the first, the workman makes, in the perpendicular face of a tier, vertical then horizontal incisions which will form two dimensions of the slab. When a certain number of these incisions are made he cuts the clay mass vertically with the long-handled tool in a line parallel to the face of the tier and at about 15 centimetres (6 inches) from that face. In consequence of the previous cuts the slab of clay comes away, and the workman lays it down near him. Some may be seen to the left in Fig. 8.

By reason of its plasticity rich clay sticks to the tools and would prevent all working if care were not taken, to avoid this inconvenience, to dip the tool frequently into a bucket of water.

Transport

Except in the case we have mentioned above, clay is rarely used at the place where it is extracted. It has always to be transported from the pit to the manufactory. If the distance is very short, or if local conditions prevent other means, the classic wheelbarrow is used. The English model is the best; the slope of the sides and their slight projection above the bottom place the centre of gravity much lower, relatively to the shafts, than in the French wheelbarrow, and thus render it more stable and easier to move.

Another important advantage is that the contents may be discharged by turning the barrow through an angle of 450, resting it still upon the wheel, and without the man being obliged to move or let go the shafts; the discharge is therefore quick, and can take place on a narrow plank, which is an advantage in certain cases (Brabant, Portefeuille de l'ing*šnieur de chemin de fer). As the wheel of the barrow, by passing continually over the same line, would soon make a rut, especially in rainy weather, and would thus make wheeling difficult or even impossible, it is run upon deal planks 22 centimetres (9 inches) wide and of different lengths. These planks are imbedded in the ground in order not to hamper the walking of the men. Sometimes plates of sheet-iron are substituted for these planks. In damp weather the clay, which always gets deposited on these wooden paths, makes them very slippery and even dangerous if on a slope. This inconvenience may be remedied by occasionally strewing some sand on them.