Page:Vitruvius the Ten Books on Architecture.djvu/241

203 broken stone in the proportions, if it is new, of three parts to one of lime; if it is old material used again, five parts may answer to two in the mixture. Next, lay the mixture of broken stone, bring on your gangs, and beat it again and again with wooden beetles into a solid mass, and let it be not less than three quarters of a foot in thickness when the beating is finished. On this lay the nucleus, consisting of pounded tile mixed with lime in the pro­portions of three parts to one, and forming a layer not less than six digits thick. On top of the nucleus, the floor, whether made of cut slips or of cubes, should be well and truly laid by rule and level.

4. After it is laid and set at the proper inclination, let it be rubbed down so that, if it consists of cut slips, the lozenges, or triangles, or squares, or hexagons may not stick up at different levels, but be all jointed together on the same plane with one another; if it is laid in cubes, so that all the edges may be level; for the rubbing down will not be properly finished unless all the edges are on the same level plane. The herring-bone pattern, made of Tibur burnt brick, must also be carefully finished, so as to be without gaps or ridges sticking up, but all flat and rubbed down to rule. When the rubbing down is completely finished by means of the smoothing and polishing processes, sift powdered marble on top, and lay on a coating of lime and sand.

5. In the open air, specially adapted kinds of floors must be made, because their framework, swelling with dampness, or shrinking from dryness, or sagging and settling, injures the floors by these changes; besides, the frost and rime will not let them go unhurt. Hence, if necessity drives, we must proceed as follows in order to make them as free from defects as possible. After finishing the plank flooring, lay a second plank flooring over it at right angles, and nail it down so as to give double protection to the framework. Then, mix with new broken stone one third the quantity of pounded tile, and let lime be added to the mixture in the mortar trough in the proportion of two parts to five.

6. Having made the bedding, lay on this mixture of broken