. The book of the garden. Gardening. abutments are introduced. The nearer they resemble a piece of rock of the same character as that existing naturally in the vicinity, the better. A parapet, or hand-rail, is also introduced, both for safety and effect. The footway is covered as just described, and as in all the other examples. The uprights in the parapet are mortised into the floor of the bridge, and also into the top of the hand-rail, as are also the slightly-curved pieces between them; and, although bolted together at their middles, a strong withing is wound round them, as if they were tie
. The book of the garden. Gardening. abutments are introduced. The nearer they resemble a piece of rock of the same character as that existing naturally in the vicinity, the better. A parapet, or hand-rail, is also introduced, both for safety and effect. The footway is covered as just described, and as in all the other examples. The uprights in the parapet are mortised into the floor of the bridge, and also into the top of the hand-rail, as are also the slightly-curved pieces between them; and, although bolted together at their middles, a strong withing is wound round them, as if they were tied by that means alone. Fig. 999 is a bridge of great strength and simple construction. It will be seen that it is upon the principle of the arch : the greater the weight on the centre, the greater the pressure on the abutments ; and while these remain sound, no weight Fig. can break it down. We believe that this bridge was the invention of Napoleon, and first used during his inroads into Germany in the early part of his eventful career. We have often used this sort of bridge for temporary purposes, as it can be put up and taken down in a very short time. The principal part of the construction is to make the abutments sound with coarse stone-work. Four larch trees (or any other that are straight) are cut into lengths, a little more than half the width to be spanned. Their but-ends are set in holes left in the abutments for their reception; the other ends are elevated upon tressels, or held up by men, until the two cross bearers, the sections of which are shown at a a, are placed ; the one resting on the top of the longitudinal bearer, or tree, on the right-hand side, and the other on that on the left-hand side. The top ends of the longitudinal bearers on each side then fall down, and rest on the top of the cross bearers, thus forming a rude arch of great strength. The cross bearers are kept in their places by having an iron or timber bolt driven through them and into the l
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectgardening, bookyear18
