Makeshift Life-belt.--A moderately effective life-belt may be made of holland, ticking, canvas, or similar materials, in the following manner, and might be used with advantage by the crew of a vessel aground some way from the mainland, who are about to swim for their lives:--Cut out two complete rings, of 16 inches outer diameter and 8 inches inner diameter; sew these together along both edges, with as fine a needle as possible and with double thread: add strong shoulder-straps, so that it shall not, by any possibility, slip down over the hips; and, lastly, sew into it a long narrow tube, made out of a strip, a foot long and two inches wide, of the same material as the belt. At the mouth of this, a bit of wood, an inch long, with a hole bored down its middle, should be inserted as a mouthpiece. Through this tube the belt can be re-inflated by the swimmer while in the water, as often as may be necessary; and, by simply twisting the tube and tucking its end in the belt, its vent can always be closed.
After a canvas belt is thoroughly drenched, it will hold the air very fairly: the seams are its weakest parts. For supporting a swimmer in calm water, a collar is as good as a belt.
Transport on Water.--Parcels.--The swimmer"s valuables may as well be put inside the empty vessel that acts as his float, as in the turban on his head (see "Floats"). A goat-skin is often filled half full of the things he wants to carry, and is then blown out and its mouth secured. A very good life-belt may be bought, which admits of this arrangement: it has a large opening at one end, which is closed by a bra.s.s door that shuts like the top of an inkstand, and is then quite air-tight.
A small parcel, if tightly wrapped up in many folds, will keep dry for a long time, though partly immersed in water: the outside of it may be greased, oiled, or waxed, for additional security. If deeply immersed, the water is sure to get in.
Swimming with Horses.--In crossing a deep river, with a horse or other large animal, drive him in: or even lead him along a steep bank, and push him sideways, suddenly into the water: having fairly started him, jump in yourself, seize his tail, and let him tow you across. If he turns his head with the intention of changing his course, splash water in his face with your right or left hand, as the case may be, holding the tail with one hand and splashing with the other; and you will, in this way, direct him just as you like. This is by far the best way of swimming a horse: all others are objectionable and even dangerous with animals new to the work,--such as to swim alongside the horse, with one hand on his shoulder; or, worst of all, to retain your seat on his back. If this last method be persisted in, at least let the rider take his feet out of the stirrups, before entering the water.
[Sketch of horse and man crossing river].
To float a Wagon across a River.--It must be well ballasted, or it will a.s.suredly capsize: the heavy contents should be stowed at the bottom; the planking lashed to the axletrees, or it will float away from them; great bundles of reeds and the empty water-vessels should be made fast high above all, and then the wagon will cross without danger. When it is fairly under weigh, the oxen will swim it across, pulling in their yokes.
Water Spectacles.--When a man opens his eyes under water, he can see nothing distinctly; but everything is as much out of focus, as if he looked, in air, through a pair of powerful spectacles that were utterly unsuited to him. He cannot distinguish the letters of the largest print in a newspaper advertis.e.m.e.nt; he cannot see the s.p.a.ces between the outstretched fingers, at arm"s length, in clear water; nor at a few inches" distance in water that is somewhat opaque. I read a short paper on this subject, at the British a.s.sociation in 1865, in which I showed the precise cause of this imperfection of vision and how it might be remedied. If the front of our eyeb.a.l.l.s had been flat, we should have had the power of seeing under water as clearly as in air; but instead of being flat, they are very convex, consequently our eye stamps a concave lens of high power into the water, and it is the seeing through this concave eyegla.s.s which our eyeball makes for itself, that causes the indistinctness of our vision. Knowing the curvature of the eyeball, it is easy to calculate (as I did in the memoir mentioned above) the curvature of a convex lens of flint-gla.s.s that should, when plunged into water, produce effects of an exactly equal and contrary value, exactly neutralizing the effects of the concave eyegla.s.s of water, if it were held immediately in front of the pupil of the eye. I have made several experiments with a view to obtaining serviceable spectacles, for seeing under water. The result is as follows:--experience has shown the distance from the eyeball at which spectacle-gla.s.ses can be most conveniently placed; now at that distance, the joint effect of the concave water-lens and the convex gla.s.s spectacle-lens, is to produce an opera-gla.s.s of exceedingly low magnifying power, that requires a small adjustment for accurate definition at different distances.
If the spectacle-lens be of flint-gla.s.s and doubly convex, each of its faces should have a curvature of not greater than 6 1/2 tenths of an inch, nor more than 8 1/2 tenths of an inch in radius: within these limits, it is practicable to obtain perfectly distinct vision under water by pressing the spectacles forwards or backwards to a moderate degree.
Lenses of these high magnifying powers are sometimes sold by spectacle-makers, for persons who have undergone an operation for cataract. I have tried, but hitherto without much success, to arrange the fittings by which the lenses are secured so that by a movement of the jaw or by an elevation of the eyebrows, I could give the necessary adjustment of the gla.s.ses, leaving my hands free for the purpose of swimming. (See also, under "Fishing;" "To see Things deep under Water.")
RAFTS AND BOATS.
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 wherethe logs cross, and a few pegs and lashings. Briers, woodbines, etc., 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 f. 1: it is a stout, little wand, bent over the cross piece, and wedged into holes in the framework.
[Sketch of raft].
[Fig 1 and Fig 2 show fastening arrangements].
The rafts of European rivers are usually built on sh.o.r.e, 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 gra.s.s thrown on to make a platform, is very buoyant and serviceable.
Floating power of various Woods.--The floating power of a raft depends on the buoyancy of the wood of which it is made. I give, in a Table (p. 90), a list of the specific gravities of a few well-known woods; and have annexed to them a column of what may be called their "specific floating powers."*
[Footnote] *Specific floating power = (1/Spec. Gr.)--1. (Mem., the Table of these, in previous editions is incorrect.) Burden = weight of raft x specific floating power. Weight of wood required to support a given burden = Burden x (Spec. Gr./1-Spec. Gr.); the last column gives the latter factor.
Hence, to find the actual floating power of a raft, it is simply necessary to multiply its weight into the specific floating power of the wood of which it is made.
Thus, a raft of 12 logs of larch, averaging 30 lbs. each, weighs 360 lbs.; this multiplied by .47, is equal to 169 lbs. very nearly, which is the weight the raft will support without sinking. Poplar is the lightest on the list.
Specific Specific Factors to be multiplied Gravities. Floating Powers. into burden to find weight of raft just able to support it.
Alder........ .80 .25 4.0 Ash........... .85 .18 5.7 Beech......... .85 .18 5.7 Elm....... .59 to .80 .70 to .25 1.4 to 4.0 Fir...... .47 to .60 1.13 to .66 0.9 to 1.5 Larch..... ... .53 .89 1.1 Oak........... .75 .33 3.0 " heart of.. 1.17 sinks cannot be used Pine..... .40 to .63 1.50 to .60 0.7 to 1.7 Poplar........ .38 1.63 0.6 Willow........ .59 .70 1.4
Examples: -- a raft of alder, weighing 200 lbs., would just support 200 x .25 or 50 lbs.
A burden of 100 lbs. would require a raft of alder, weighing not les than 100 x 4.0, or 400 lbs. to support it.
Burning down Trees.--Where there are no means at hand to fell trees, they should be burnt down; two men may attend to the burning of twenty trees at one and the same time. When felled, their tops and branches, also, are to be trimmed by fire. (See "Hutting Palisades.")
Reed Rafts.--Mr. Andersson, in exploring the Tioughe River, in South Africa, met with two very simple forms of rafts: the one was a vast quant.i.ty of reeds cut down, heaped into a stack of from 30 to 50 feet in diameter, pushed out into the water, and allowed to float down stream: each day, as the reeds became water-logged, more were cut and thrown on the stack: its great bulk made it sure of pa.s.sing over shallow places; and when it struck against "snags," the force of the water soon slewed it round and started it afresh. On an affair of this description, Mr.
Andersson, with seven attendants, and two canoes hauled up upon it, descended the river for five days. The second reed raft was a small and neat one, and used for ferries; it was a mattress of reeds, 5 feet long, 3 broad, and some 8 inches thick, tied together with strips of the reeds themselves; to each of its four corners was fixed a post, made of an upright f.a.ggot of reeds, 18 inches high; other f.a.ggots connected the tops of the posts horizontally, in the place of rails: this was all; it held one or two men, and nothing but reeds or rushes were used in its construction.
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.
[Sketch fig. 1 and fig. 2 showing gourd rafts].
African Gourd Raft.--Over a large part of Bornu, especially on its Komadugu--the so-called River Yeou of Central Africa--no boat is used, except the following ingenious contrivance. It is called a "makara," or boat pareminence.
Two large open gourds are nicely balanced, and fixed, bottom downwards, on a bar or yoke of light wood, 4 feet long, 4 1/2 inches wide, and 3/4 or 1 inch thick. The fisherman, or traveller, packs his gear into the gourds; launches the makara 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 makara on his back (fig. 2). The late Dr. Barth wrote to me, "A person accustomed to such sort of voyage, sits very comfortably; a stranger holds on to one of the calabashes. There is no fear of capsizing, as the calabashes go under water, according to the weight put upon them, from ten to sixteen inches. The yoke is firmly fastened to the two calabashes, for it is never taken off. I am scarcely able, at present, to say how it is fastened. As far as I remember, it is fixed by a very firm lashing, which forms a sort of network over the calabash, and at the same time serves to strengthen the latter and guard it against an accident." It is obvious that the gourds might be replaced by inflated bags or baskets, covered with leather, or by copper or tin vessels, or by any other equivalent. I quite agree with Dr. Barth, that a makara would be particularly suitable for a traveller. In Bornu, they make large rafts, by putting a frame over several of these makara, placed side by side.
[Sketch of sailing boat].
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. Recollect Robinson Crusoe"s difficulty in launching his canoe after he had made it. (See "Rafts of Wood.") It is not a difficult, though a tedious operation, to burn out hollows in wood; the fire is confined by wet earth, that it may not extend too far to either side, and the charred matter is from time to time sc.r.a.ped away, and fresh fire raked back on the newly-exposed surface. A lazy savage sill be months in making a single canoe in this way.
[Fig 1 and fig 2 sketch of boat and pattern].
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. If the reader will take the trouble to trace fig. 2 on a stout card, to cut it out in a single piece (cutting only half through the cardboard where the planks touch), and to fasten it into shape with pieces of gummed paper, he will understand the architecture of the boat more easily than from any description. If he wishes to build a boat he had best proceed to make as large a model in pasteboard as his materials admit, and to cut the planks to scale, according to the pattern of his model. The grace of the boat depends on the cut of its planks, just as much as the elegance of a dress does on that of its cloth. These three-plank canoes are in frequent use in Norway. Bark may be used instead of planks. If the canoe be built of five planks instead of three, a second narrow side-plank being added above each gunwale, the section of the canoe is decidedly improved.
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 the 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.
It is perfectly easy to get into a macintosh-boat, after having been capsized out of it into deep water.
Basket-boat with Canvas Sides.--FitzRoy gives an account of a party of his sailors, whose boat had been stolen while they were encamped, putting out to sea in a large basket, woven with such boughs as were at hand, and covered with their canvas tent--the inside of which they had puddled with clay, to keep the water from oozing through too fast. They were eighteen hours afloat in this crazy craft. I mention this instance, to show how almost anything will make a boat. Canvas saturated with grease or oil is waterproof, and painted canvas is at first an excellent covering for a boat, but it soon becomes rotten.
Canoe of Reeds or Vegetable Fibre.--A canoe may be made of reeds, rushes, or the light inner bark of trees. Either of these materials is bound into three long f.a.ggots, pointed at one end: these are placed side by side and lashed together, and the result is a serviceable vessel, of the appearance fig. 1, and section as fig. 2. The Lake t.i.ticaca, which lies far above the limit of trees, is navigated by boats made of rushes, and carrying sails woven of rushes also. Little boats are sometimes made of twigs, and are then plastered both inside and outside with clay, but they are very leaky.
[Fig 1 and fig 2--sketches of reed canoe].
Hide Tray.--This is a good contrivance; and if the hide be smoked (see "Hides") after it is set, it is vastly improved. In its simplest form, Peruvian travellers describe it as a dish or tray, consisting of a dry hide pinched up at the four corners, and each corner secured with a thorn. The preferable plan is to make eyelet-holes round its rim, and pa.s.s a thong through, drawing it pretty close: the tray is kept in shape, by sticks put inside and athwart its bottom.
Coracle and Skin Punt.--If a traveller has one hide only at his disposal he should make a coracle, if he has two, a punt. This last is a really useful boat; one in which very great distances of river may be descended with safety, and much luggage taken. Hide boats are very light, since the weight of a bullock"s skin only averages 45 lbs.; but, unless well greased, they soon rot. When taken out of the water, they should be laid bottom upwards to dry. To make a proper and substantial coracle, a dozen or more oxier or other wands must be cut; these are to be bent, and have both ends stuck in the ground, in such a way as to form the framework of the required boat, bottom upwards, much like half a walnut-sh.e.l.l in shape, but flatter. Where these wands cross, they should be lashed; and sticks should be wattled in, to fill up gaps. A raw hide is then thrown over the framework, sewn in place, and left to dry. Finally, the projecting ends of the osiers have to be cut off. Should this boat, by any chance, prove a failure, the hide is not wasted, but can be removed, soaked till soft, and used again.
A skin punt requires two bullocks" or other hides, and also about ten small willow-trees, or other tough flexible wood, 14 feet long. Captain Palliser says that a couple of days is sufficient for two people to complete an entire punt of this description. He has been so good as to furnish me with the following minute description of the way of making this very useful boat.
1. The keel, stem and stern might be in one; but because the stem and stern ought to be strong, this whole line is made of two small trees lashed together with the thick ends outwards, as in fig. 1, where AB is a lithe clean little willow-tree, and ab another similar one. They are lashed together at their taper ends.
2. Cut notches half-way through KK, at about 20 to 25 inches from each end; then turn up the notched portions, and you have stem, keel and stern, all in one piece, as in fig. 2.
[Fig 1 and Fig 2 sketches].
3. Stake out the ground, according to the size your boat will cover, by driving eight strong pointed stakes of wood into the ground; to these lash four cross (willow-tree) sticks, notched in two places, so that each of these four willows shall form two knees, as well as run across the bottom of the boat.