GABION BRIDGE.
Gabion bridge, to make.
Tartar bridges, to make.
Rivers which are too wide to be crossed by the one-tree bridge, and yet of inconsiderable breadth, may be crossed by the use of the gabion bridge, which is thus constructed: First, prepare as many strong wicker gabions as the width of the stream will render necessary. About 14ft. apart will be found a convenient distance to place them. Their height will depend on the depth of the water. Three feet at least should be allowed between the surface of the stream and the upper edge of the gabion. Where suitable poles and sticks for gabion making cannot be obtained trees should be felled and split up, as for rails (see [p. 273]). The bars thus obtained should be cut up into proper lengths, and, by the use of the axe and auger, converted into large deep crates, such as are used for packing earthenware. These are made by boring rows of auger holes in strong wooden bars, and then driving the sharpened ends of the lesser bars into them until the crate is finished, no nails or metal fastenings being required. Whether the crate or gabion is used, the principle of construction observed in making the bridge is the same. The first gabion, after being secured to the end of a stout rope, is launched from the bank, and then guided, end upward, by the aid of forked setting poles, to its proper position. Stones, pebbles, or pieces of broken rock, are now cast pell-mell by hand into the open mouth of the gabion, which is held down by the setting pole until fixed in its position by the weight of the mass within it. When quite full two or three stout poles are laid side by side for a man to walk over. He takes up his station on the gabion, and aids in arranging the ends of two side logs which are pushed out to him from the shore, and placed wide enough apart to give sufficient width to the intended bridge. Transverse bars formed of split logs are now rapidly treenailed on, as shown in the accompanying illustration. The second gabion is now launched from the first, the stone collectors with bags and baskets walk out, cast their loads, and return for more, proceeding in the same manner until the bridge is finished. Tartar bridges, to make. When travelling among the Tartars we had on more than one occasion to pass our mules and horses over rather insecure-looking bridges formed by the natives. They were alike in construction, and were made by laying three long strong poles, or rather small tree trunks, side by side from bank to bank. Across these alternately (butt-end and top), as shown in the engraving on next page, was laid a close row of tightly-bound bundles or faggots of small brushwood. On these bundles of twigs large flat slabs of turf, grass side upward, were placed and stamped compactly down, forming serviceable and really good bridge ways. A small river can be easily crossed by men on foot by simply felling a tree of sufficient girth and length across it. Should there be a number of packs or loads to pass across, it will be well, if the party is a large one, to so station men along the tree trunk that they can pass the bundles or articles from hand to hand, just as firemen hand buckets of water, thus saving unnecessary labour. A rope stretched across greatly aids the men in keeping their balance.
Extempore jetty, to build.
TARTAR POLE AND FAGGOT BRIDGE.
We, on one occasion, when encamped on the banks of a large Indian river, were called on to provide for the immediate transport of a battery of field guns, waggons, horses, &c., to the opposite side. Some large native boats were procured, but they, even when empty, drew so much water, that they could not be made to approach within some distance of the shore. We therefore felled two trees, which fortunately stood side by side, letting their crowns fall from the bank, well out into the stream. We soon foraged out three large dug-out canoes, which were concealed among the reeds hard by. These, with our own axe, and those of two stalwart-limber gunners, we split into lengths of uneven plank. Whilst we were doing this, a party had been at work forcing down large heavy branches between the two tree trunks, and on these compactly-bound faggots of brushwood (which a number of natives attached to the expedition prepared close at hand) were rammed and stamped down. Tho boards procured by cutting up the canoes were arranged side by side on this bed, their ends being secured by burden ropes knotted together and hitched over them, as shown at [Fig. 1, p. 292]. We now employed the natives in throwing buckets and bags of earth and sand thickly over and between the planks. Over this extempore jetty—which reached out to the boats, on some of which platforms had been erected—all our battery, consisting of two 12-pounder howitzers, and four 6-pounder guns, with all their equipment, passed in perfect safety. The work was not commenced until late in the afternoon, and all had crossed long before morning.