Guadi e Raft - Galton - Viaggiare e sopravvivere di Graziella Martina

Vai ai contenuti


    Rafts.-Rafts of Wood.-Rafts are made of logs of wood, held together by pairs of cross-bars, one of each pair lying above the raft and the other below; then, the whole may be made quite firm by a little judicious notching where the logs cross, and a few pegs and lashings. Briers, woodbines, &c., will do for these. If the logs are large, they should be separately launched into the river, and towed into their proper places. Outriggers vastly increase the stability of a raft. The raft-fastening in common use, is shown in fig. 1: it is a stout, lithe wand, bent over the cross piece, and wedged into holes in the framework.
    The rafts of European rivers are usually built on shore, and launched into the water: three slides are laid for the purpose, on the sloping bank of the river; upon these are laid the four poles, secured together by their ends, which are to form the framework of the raft (fig. 2). Other poles are put in between, until the whole is complete.
    Bamboo rafts.-Where bamboo is plentiful, it is preferable to any other material for rafts. A few bamboos lashed into the shape of an ordinary field gate, but with two diagonals, and with handfuls of grass thrown on to make a platform, is very buoyant and serviceable.
    Rafts of distended Hides.-“A single ox-hide may be made into a float capable of sustaining about 300 lbs.; the skin is to be cut to the largest possible circle, then gathered together round a short tube, to the inner end of which a valve, like that of a common pair of bellows, has been applied: it is inflated with bellows, and, as the air escapes by degrees, it may be refilled every ten or twelve hours.” ('Handbook for Field Service.')
    We read of the skins of animals, stuffed with hay to keep them distended, having been used by Alexander the Great, and by others.
    Goatskin rafts are extensively used on the Tigris and elsewhere. These are inflated through one of the legs: they are generally lashed to a framework of wood, branches, and reeds, in such a way that the leg is accessible to a person sitting on the raft: when the air has in part escaped, he creeps round to the skins, one after the other, untying and re-inflating them in succession.
    African Gourd Raft.-Over a large part of Bornu, especially on its Komádugu – the so-called River Yeou of Central Africa-no boat is used, except the following ingenious contrivance. It is called a “mákara”, or boat par éminence.
    Two large open gourds are nicely balanced, and fixed, bottom downwards, on a bar or yoke of light wood. The fisherman, or traveller, packs his gear into the gourds; launches the mákara into the river, and seats himself astride the bar. He then paddles off, with help of his hands (fig. 1). When he leaves the river, he carries the mákara on his back (fig. 2).
    Rude Boats.-Brazilian Sailing-boat.-A simpler sailing-boat or raft could hardly be imagined than that shown in the figure; it is used by fishermen in Brazil.
    Log Canoes are made by hollowing out a long tree by axe and by fire, and fastening an outrigger to one side of it, to give steadiness in the water.
    Canoe of  Three Planks.-A swift, safe, and graceful little boat, with a sharp stem and stern, and with a bottom that curves upwards at both ends, can be made out of three planks. The sketch, fig. 1, is a foreshortened view of the boat, and the diagram, fig. 2, shows the shape of the planks from which it is made. The thwart or seat shown in fig. 1 is important in giving the proper inclination to the sides of the boat, for, without it, they would tend to collapse; and the bottom would be less curved at either end.
    Inflatable India-rubber Boats are an invention that has proved invaluable to travellers: they have been used in all quarters of the globe, and are found to stand every climate. A full-sized one weighs only 40 lbs. They have done especial service in Arctic exploration; the waters of the Great Salt Lake, in the Mormon country, were first explored and navigated with one by Fremont; they were also employed by Dr. Livingstone on the rivers of South Africa. They stand a wonderful amount of wear and tear; but, as boats, they are inferior to native canoes, as they are very slow in the water: it is, indeed, impossible to paddle them against a moderate head-wind. For the general purposes of travellers, I should be inclined to recommend as small a macintosh-boat as can be constructed; just sufficient for one, or at most for two, persons; such as the cloaks that are made inflatable, and convertible into boats. A traveller wants a portable boat, chiefly as means to cross over to a village for help, or to carry his valuables across a river, while the heavy things are risked at a ford; or for shooting, fishing, or surveying. Now a very small boat, weighing about ten pounds, would do as well for all these purposes as a large one, and would be far more portable.
    Fords.-In fording a swift stream, carry heavy stones in your hand, for you require weight to resist the force of the current: indeed, the deeper you wade, the more weight you require; though you have so muche the less at command, on account of the water buoying you up.
    Rivers cannot be forded if their depth exceeds 3 feet for men or 4 feet for horses. Fords are easily discovered by tying a sounding-pole to the stern of a boat rowing down the middle of the stream, and searching those places where the pole touches the bottom. When no boat is to be had, fords should be tried for where the river is broad rather than where it is narrow, and especially at those places where there are bends in its course. In these the line of shallow water does not run straight across, but follows the direction of a line connecting a promontory on one side to the nearest promontory on the other.
Torna ai contenuti