PLUMBEE-WOKK.] BUILDING 503 turn up against it from 5 to 7 inches, according to circum stances ; and the turning up under the slates, tiles, or other roof covering, to a gutter, should be to the level of that against the wall at the least. The turning up against the wall should be covered by a flashing. This is a piece of lead let into one of the joints of the wall above the edge of the gutter lead, and dressed neatly down over it, to pre vent water from getting in behind it (Plate XXVI. fig. 6). Parallel or box-gutters are necessary next parapets where a curb roof is formed, and are useful in valleys of small roofs where the depth for it can be obtained. Fig. 117 is a section of such a gutter next to a parapet wall, in which A is the wall plate ; B the tie- beam of the roof ; C a bearer for carrying one end of the gutter bearer D, the other end being tenoned into the pole plate K ; E the gutter boards carried by its bearers ; G the lead gutter, laid in somewhat of an oval shape by the small angle fillets, FIG, 117. -Gutter and Hoof- Timbers. which are useful in preventing the lead being returned at a right angle, where it is sometimes cracked in lay ing ; H the flashing ; I the eaves board for raising the last row of slates, over which the lead is fixed ; L the common rafter; M the slating; 1ST the principal rafter forming part of the truss of the roof ; O the saddle back coping of the wall, throated on both sides. Where thick walls could be obtained, it was usual to form this sort of gutter below the timbers of the roof, whereby they were kept dry, and damage from the overflowing of the gutter prevented. The same result is occasionally achieved by a cornice projecting more than usual, the gutter being formed on it in place of a real blocking course. If the gutters and flats are to be often walked upon, they should be protected by deal lattice work raised on fillets but not fixed. Snow falling down the slopes is prevented by this from stopping the gutters, and it also lessens the action of the sun upon the lead-work. Lead on ridges and hips and the top and sides of dormers, not being in sufficient masses to be secured by its own weight, must be fastened by nails bossed over. In making cisterns and reservoirs, unless they be cast (and these are now disused), the sheets of lead must of necessity be joined by soldering ; but the water they are intended to contain protects the lead from the frequent and sudden changes to which in other and more exposed situations it is exposed. The lead-work forms a lining to a wood case, which has grooved and tongued sides and a bottom. But cisterns are now commonly made of zinc, or of galvanized iron, or of slate ; the last two do not require a casing, but may perhaps be enclosed in a closet. Service or water pipes to and from the cisterns, as also waste or overflow pipes, are also made of lead, and described by their bore, as i in., in., inch, and so on. They are generally supported and attached to the wall by means of iron holdfasts. Iron water pipes are fixed where lead will probably be stolen. The opinion that some waters are injured by coming in con tact with the lead of cisterns and pipes, has led to the for mation of pipes of tin encased in lead. The water companies are now requiring a water regulator to be put to each closet, or a water waste preventor where the constant supply is obtained, but these are a very troublesome addition to the plumber s work, on account of the difficulty of keeping them in working order. The constant supply system re quires taps of a different construction from those used in other cases ; these are called " screw down valves," from their action, and resist the pressure of the water. As re pairs must occasionally be needed to the main pipes, it is recommended that, to prevent inconvenience, one or more cisterns be always provided in the house for containing two days supply of water. Rain-water trunks and pipes are made of a certain number of pounds weight to the yard in length, according to the bore or calibre that is required. The pipes are fitted with large case heads above, to receive the water from the gutter spouts, and with shoes to deliver the water below; they are fixed or attached to the walls of buildings of stone usually with flanges of lead, which are secured by means of spike nails, iron and other metals having superseded lead where brick is used or economy requires the substitution. The varieties of water-closet apparatus, of which Under- hay s patent is one of the best, are too numerous to be here described. Pumps of all kinds and powers are amongst the other matters coming within the plumber s province, together with cocks, bosses, ferules, washers, valves, balls, grates, traps, funnels, service boxes, and a numerous collection of other articles. A metal occasionally used for roofs in lieu of lead is known Patent by the name of Wetterstedt s patent marine metal. It is marine composed of lead and antimony. Its advantages are its metal - malleability, great tenacity, elasticity, and durability, and its resistance to acids, oxidation, and the action of the sun and atmosphere. It is manufactured in sheets of certain sizes, from 3 ft to 8 ounces per foot, according to the pur poses for which it is required, the latter weight being useful for lining damp walls. It should be secured with wrought copper nails. A patent metallic canvas is also manu factured of various substances and strength, serving for waterproof and secure covering. Sheet copper was formerly used on account of its lightness Copper to cover roofs and flats. The thickness generally varied roofing. from 12 to 18 ounces per square foot. It was laid like lead, but the plates being of small size were soldered together. It will be well to notice that water collected from copper channels must not be used for culinary pur poses, as a film of verdigris is formed, which is poisonous. Copper is much used for roofing in foreign countries. Lead and copper, where economy is required, are super- Zinc roofs, seded by zinc, which is not only much cheaper, but when good is nearly as durable, and is not so liable to be corru gated by the action of the sun. Zinc is subject to oxida tion ; but the oxide, instead of scaling off as that of iron does, forms a permanent coating on the metal. Its expan sion and contraction are greater than those of any other metal. Zinc sheets as manufactured vary in quality, some being very brittle. That supplied by the Vielle Montagnc Zinc Mining Company possesses a high reputation for purity and excellence. Zinc must be laid like lead, without fixing either by nails or solder. No. 13 gauge, weighing 19 oz. 10 drs., is the least for roofs, flats, and gutters on board ing. No. 14, a medium thickness, weighing 21 oz. 13 drs., is used for roofs and flats ; and No. 15 or 16, weighing 24 oz. and 26 oz. 3 drs. per foot superficial, for best work and roofs without boards. Zinc pipes are extensively used as chimney pots ; stamped and moulded ornamental zinc for dormers, Mansard roofs, vanes, guttering, and rain-water pipes, cisterns, &c. ; and perforated zinc for blinds and for ventilation. Tin cannot class with the building materials in England, Tin roofing, although it is extensively used for covering roofs in America and in Russia. The best publications on this trade arc the makers price books and lists of articles made and sold by them. See also tlie article
METALLUKGY.