THE patterned tiles used in the Middle Ages for pavements, and occasionally for a wall covering or decoration, were made of clay squeezed into wooden moulds, usually square, like a shallow box with no lid; the clay was made level and smooth on the top by its surface being rubbed over with some flat tool. The tile so made was turned out of the mould, and while it was still soft, the pattern, cut on a piece of wood the same size as the tile, was pressed on to it, leaving an impression like a seal does on soft sealing-wax. We know that the pattern moulds were made of wood, for in one or two cases there are lines on the tiles showing that the moulds had slightly split along the grain. The tile thus formed was then put on one side to dry to a certain extent, and when it had become hard enough to handle, a' slip' made of white clay, mixed with a considerable amount of water to make it more liquid than the body of the tile, was run into the hollows made on the surface. More often than not the tile makers were very careless, and the consistency of the clay for the tile or for the 'slip' varied so much that different effects were accidentally obtained with the same mould. Sometimes the 'slip' did not fill the impressions, at other times too much was used and the superfluous material was not too carefully removed; it is the variations thus caused which make the old tiles so attractive while the wellmade modern counterparts are so much the reverse.