As from this point of our journey to its very conclusion the buildings—whether the great _ksor_, or walled fortresses, of Tafilet or the humble cottage of the Berber of the northern slopes of the Atlas—are all constructed of the same material, _tabia_, it may render more clear the constant use of the word in the descriptions of scenery and villages if I describe here the manner in which _tabia_ is used, and of what it consists. Roughly it may be said to be cement without lime—in other words, the soil, of sand, gravel, and pebbles, beaten into a consolidated mass. The manner in which it is employed is the following. The foundations of a building are sunk and the ditch filled in; then from the level of the ground to the height of usually some 2 to 3 feet stakes are driven into the earth at each side of the ditch, and on the inside planks are arranged parallel with the soil. Quantities of loose gravel and pebbles are now brought, and the space intervening between the planks is filled up with the material, which, by means of being constantly beaten down with heavy blocks of wood at the end of poles—_mrakas_, the Moors call them—becomes a solid mass. Upon its drying the planks are removed and replaced above the first stratum of wall, the gravel being treated in the same manner. In this way a solid and tolerably durable material is obtained, subject to but one destroying action, that of water. On the northern slopes of the Atlas, where the rains are heavy, the walls of the houses are protected almost always by overhanging roofs, constructed on beams which project 2 feet or more over the wall. Across the beams and at right angles to them is laid a flooring of dried canes, which again is covered with brushwood. Beaten into the brushwood is a flat roof of adhesive clay, which is held firmly in its place by the twigs which intersect it in every direction. On the southern side of the Atlas range, however, the rainfall is exceptionally small, and there is no necessity for the overlapping roofs, the material being of sufficient durability and strength to withstand the rare showers that fall there.