Gate. A gate consists of framework, as in a b c d, hinged or hung to a gate-post e, firmly secured to the ground, and catching on a latch attached to another gate-post at the opposite side of the opening. This framework is generally filled in with five horizontal bars, as f f, sometimes with vertical ones. To prevent the weight of the gate acting in the direction of the arrow, as at g, an essential part of an arrangement of the gate is the diagonal strut or brace h h, forming the frame into two triangles, which is the strongest form of all. To produce uniformity another strut may be added, as i i. In fig. 285 we illustrate part of a gate with rails and low-coped wall.
In the various works of the builder, in making excavations, as those for drains, tunnels, and the repairing of decayed or dangerous houses, timber is used in a variety of ways, the operation being known as "shoring-up." In shoring-up a drain the simplest arrangement is shown in fig. 285, in which a a are the sides of the excavation, the interior is either lined with planks, as b b, or planks, as b b, are placed at intervals vertically, and kept apart by the horizontal stays c c c, or by diagonal ones, as d d. The shoring-up of the sides of an open excavation, or a wall which shows signs of decay and failure, may be effected by the arrangement shown at A in fig. 286. Fig. 286a illustrates a method for "underpinning" a wall a a, the side elevation of which is shown at C in same figure. By "underpinning" is meant the operation of supporting the upper part of a building or wall, as a (C), fig. 286a, while the lower part b is being repaired or removed to be replaced by a different arrangement or new materials. The upper part is by the cross beam d and shoring e (B), while the outer end of d may be supported by a vertical piece f. We take, fig. 287, from the Building
News, a method suggested by a correspondent for shoring-up the houses of a street, on both sides of which are houses, as shown by the walls. In figs. 288 to 293 we illustrate the method of shoring-up used in the construction of the tunnel at Viezzy, on the Soissons Railway, near Paris, for which
Fig, 284a we are indebted to the volume for 1861 of the Nouvelles Annates de Constructione, published by Dunod, Paris, a most valuable work, and one abounding in fine examples of construction in various branches. Fig. 288 shows the first operation, fig. 289 being a side elevation; fig. 290 illustrates the method of shoring-up the "gallery of execution," fig. 291, do., where the opening of the tunnel is enlarged; fig. 292 the centre and the shoring-up of the masonry of the vault of the tunnel, and fig. 293 the method of underpinning the side wall of the vault.