COTTAGE DWELLINGS IN VARIOUS STYLES. i^O? roofs of this span, or even one of more than double the extent, might be covered without a single rafter appearing inside. In short, no material hitherto brouglit into notice at all approaches this, in its capacities for forming light and economical roofs of the greatest extent of span, and with the least loss of interior room. Its durability will depend on the application of oil or tar paints : for barns, sheep-houses, and various other country buildings, and for all manner of sheds, both in town and country, it is par- ticularly suitable. As the invention has only been known four or five years, much has not hitherto been done w ith it ; but there are several roofs of corrugated iron in the London Docks, and fig. 353 represents a portion of one of them. " Its length is •2'25 feet, its vsidth 40 feet, and the height of the columns on which the roof is supported 12 feet. The columns are of cast iron, a gutter of which metal is continued from column to column, the whole length of the roof; and in the gutter rests the edge of the roof. The arch is formed of several sheets of iron, curved in a reverse direction to the corrugated arches, as shown fig. 353, and riveted together longitudinally. Similar arches, connected to each other by rivets, compose the roof: every corrugated arch forms a watercourse, ending in the gutters at the side, and thereby rendering it quite water- proof. To give stability to the whole, a tie rod, fig. 354, is carried across tl:e shed ■^ 354 from each column to the one opposite. Between this shed and the brick wall is a lean-to corrugated roof, forming a half nrch, springing from the gutter, and resting against the wall, as shown in fig. 353." The walls of buildings may be constructed of this iron set on edge, either in single plates, or of double plates with a vacuity between, to lessen the effect of changes in the exterior temperature on the space enclosed. As the corrugation, or fluting, of the iron may be made either large or small, it may be adapted to the panels of doors, as in figs. 355, 356, and 357 ; ^r an 355 356
