Terrace Roofs. _Terrace roofs_ have been much used in and about London. They are formed of thin arches of tiles and cement, supported on cast-iron bearers or ribs, which are placed about three feet apart. The arch is composed of three courses of common plain tiles, bedded in fine cement without sand. In laying the tiles, laths or small slips of wood are used, resting on temporary bearers between the iron ribs; the laths being shifted as the work advances, in the course of about half an hour after the tiles are laid. Particular attention is required in bonding the tiles both ways; and they are rubbed down closely upon each other, much in the same manner as a joiner glues a joint. Sometimes these terrace roofs are coated with a layer of coarse gravel, and then with nine inches of good soil, so as to form a terrace garden. The roofs of two taverns at Hungerford Market are formed of these cemented tiles. Asphalte Roofs. _Asphalte_ or _bitumen_ has come into use as a material for roofs. It had been employed for various purposes in France for many years, but did not attract much attention till within the last eight or ten years. It is now in very general use in that country for foot pavements, flat roofs, and water-cistern linings; and in England it has also been a good deal used for the same purposes, and for barn-flooring. The particular modes in which it is employed for floors and pavements we need not here consider, but it has been used for roofs in the following manner. Mr. Pocock has patented a “flexible Asphaltic roofing,” intended to supersede the use of slates, tiles, zinc, thatch, &c., in the covering and lining of farm-buildings, sheds, cottages, and other erections; and it is approved for its durability, lightness, and economy. The weight of this material being only sixty pounds to the square of one hundred feet, the walls and timbers to support it need to be but half the usual substance; it is also a non-conductor of heat, impervious to damp, and will bear a heat of two hundred and twenty degrees without injury. This peculiar material is said to be formed of asphalte mixed with the refuse felt of hat manufactories, compressed into thin plates. Scotch Fir Roofs.