as the Gothic, with the exception that the start may be made from either the right or left hand, as the case may require. The fillet a on the two upper flanges becomes a water-tight

joint.

The shingle is nailed through the lower edge of the flange b on each side. The central longitudinal rib c imparts rigidity and adds to the effect.

Hexagonal shingles, Fig. 61, are of the same construction as the diamond, save for the right-hand flange a, which is extended. The additional fillet necessitates the laying of these shingles from the left to the right.

71. The method of laying tile shingles, from the ridge to the caves, is shown in Fig. 62. The ridge cap is the same

as that used in the other methods.

The lower flanges a of

the shingles are made with a groove b into which the next

(b)

(a)

course fits.

FIG. 62.

The chief advantage of these shingles is that all scaffolding is removed as the roof is laid, and all difficulty in making a tight joint at the point of support for the scaffold is obviated.

COPPER ROOFING.

PROPERTIES OF COPPER.

72. Copper is distinguished from all other metals by its peculiar red color. Its resistance to corrosion when exposed to the atmosphere, combined with its lightness, gives it great value as a roof covering. Copper is very malleable

and ductile, and also tenacious; it is found in most countries, the principal mines being those on the shores of Lake Superior, in the United States of America, and at Corocoro, Bolivia, South America.

73. Sheet Copper.-Copper is obtained from its ore by the following process: First, the ore is roasted or calcined; after the roasting, it is melted in a reverberatory furnace, whence it issues in the state called coarse metal; this metal is then stamped and pulverized, passed through a furnace, and afterwards melted; the resulting pure metal is roasted and then refined. The copper is then cast into ingots and afterwards rolled into sheets, which are cut to market sizes, varying from 24 in. X 48 in. to 48 in. × 72 in., and are supplied in two forms, soft or annealed, and hard or cold rolled. Both varieties may be tin plated or "tinned," when desired.

74. Tests. The qualities determining the suitability of the sheets for roofing are ductility and strength, and uniformity of gauge or thickness. The sheets must stand bending with and across the fiber, without yielding even to repeated attempts at splitting and breaking. The gauge, which varies from 1 to 30, must be as represented, and tested with a wire gauge, and the sheet must be of the full weight, corresponding to the gauge, which, in common use, ranges from 10 to 20 ounces per square foot. When a piece is broken off, the fiber should present a bright, lustrous, and silky appearance, if the copper is of the best grade. The metal should also bear stamping into form without developing fractures.

LAYING COPPER ROOFS.

75. The methods employed in laying copper roofs are usually the same as those required for tin roofing, though the flat roof laid with a lap seam is not to be commended. It is weak, and, being soldered and nailed, will not permit sufficient expansion and contraction. Where solder is used, the lock seam with cleats is best. The edges of the sheets

and all surfaces with which they come in contact should, before the seaming and folding are done, be thoroughly cleaned with chloride of zinc. When the sheets are in place, mallet them down to the roof. on one side, the folds should be surfaces shall face each other.

In case the metal is tinned turned so that the tinned Tinning is resorted to so

that the solder may flow or sweat more freely than it will on The solder used for copper roofs is the same as

the copper.

for tin roofing, but with a flux of sal ammoniac.

The standing seam method of laying should be employed where extra strength and stiffness are required, on very steeppitched roofs, and on flat surfaces where work without solder is to be carried out.

ways.

76. Roll-joint copper roofing is laid in two different In the one the roll is hollow and is secured to the roof by clips or tingles; in the other a solid roll is used, set with a trough or nailed directly to the roof.

shows the hollow

roll. The clips or

Fig. 63

sheets b are turned, and the left-hand sheet is bent over to form the lock c. This joint or lock is seamed and then turned over in a roll, as indicated by the dotted lines and the completed roll d.

77. The trough method is illustrated by Fig. 64. The

FIG. 64.

wood rolls a are 11⁄2 in. ×2 in. The trough b made of copper, in which the rolls are set, is nailed to the roof boards; the sheets

c are then bent up to the top of the trough and the edges d of the trough are locked or turned down over them. The cap e is made as indicated, and is sprung tightly over the roll. The other solid roll, shown in Fig. 65, has the roofing plate a bent up and over it, the upper sheet being the last

put in place between the rolls as the covering is laid. This, under ordinary circumstances, makes a good roof.

78. To save time and labor, flashings or other vertical jointed work should be soldered, when required, before being taken on the roof. When the sheets are in place, the solder will not flow into the vertical joints; but on the ground, the seams may be laid flat and the solder will readily soak in.

Connections between the flashings of the walls, chimneys, etc. and the gutters should be double locked, and to permit free movement, they should be unsoldered.

79. The gauge, thickness, and weight per superficial foot of copper used for roofing purposes, are given in the following table: