At Tette, on the Zambesi, there are ridges running parallel to the banks of the river, with hollows between them, which may have served as supplementary channels during extraordinary floods; and, to avoid the low-lying malaria, which is of greater specific gravity than common air, the Portuguese colonists erect their houses on these ridges. The hollows serve as streets or roadways, and also as channels to carry off the deadly exhalations, which, being heavier than air, naturally seek the lowest level. The dwelling rooms are also further elevated by being built over a basement, which serves as a store-room, the elevation of a few feet frequently making all the difference between the chance of catching fever and of escaping it. In these store-rooms they build isolated platforms about 3ft. high, on forked posts of hard wood, which are carefully swept every morning, while salt is strewed around their base to prevent the white ants approaching. Probably tar or turpentine would have the same effect, but in remote regions these are not always at command. The tarred wood of our iron house was never touched; and the camphor wood of India is valued very much on account of its immunity from their attacks.

When the Portuguese on the Zambesi build large houses that are to be divided into rooms, they build into the central and side walls a row of pillars, into the thickness of which stout poles are built, with the forks left upon them, and perhaps other rows of pillars without the connecting walls are built for the verandah.

Dr. Kirk, when consulted as to the best method of colonising the Shire, or Sheeree River, gave it as his opinion that the estates lying low in the fertile valleys should be cultivated by natives only (who in their own country do not seem susceptible to the deadly influence of fever, though when removed to another locality that is not perceptibly worse, they are as liable to be attacked as Europeans), and that the proprietors should have their residences upon the hills, as far as possible above the level of the malaria, with a small military force at their disposal, to keep order when necessary among the inhabitants of the valley. This certainly appears to be the only feasible plan of occupying such a country with any benefit to the various parties concerned.

An Indian cottage, on the banks of the Rio Negro, has been thus described:—“The main supports are trunks of some forest tree, of heavy and durable wood; but the light rafters are the straight, cylindrical, and uniform stems of the Jará palm. The roof is thatched with the large triangular leaves of the Caraná palm in regular alternate rows, neatly bound with sipos or forest creepers. The door is a frame of thin strips of wood neatly thatched over. It is of the split stems of the Pashiuba palm. In one corner is a heavy harpoon for cow-fish; it is of the black wood of the Pashiuba barriguda. By its side is a blowpipe, 10ft. or 12ft. long, and a little quiver of small poisoned arrows hangs near it. With these the Indian procures birds for food or for gay feathers, or shoots the hog or tapir; and it is from the stem and spines of two palms that they are made. His great bassoon-like musical instruments are of palm stems; the cloth to wrap his valued feather ornaments is a fibrous palm spathe, and the rude chest for his treasures is woven from palm leaves. His hammock, his bowstring, and his fishing line are fibres of palm leaves; the first from the miriti, and the other two from the tucum. The comb on his head is the hard bark of a palm. He makes fish-hooks of the spines, or uses them to puncture on his skin the peculiar markings of his tribe. His children eat the agreeable red and yellow fruit of the pupunha or peach palm, and from the assai he has prepared and offers you a favourite drink. A carefully-suspended gourd contains oil from the fruit of another, and the long elastic-plaited cylinder used for squeezing dry the mandiocca pulp to make his bread is of the bark of one of the singular climbing palms which alone can resist for any considerable time the action of the poisonous juice. In each of these cases a species is chosen adapted to the special object to which it is to be applied, and often having different uses which no other plant can serve so well.”

The arboreal dwellings of the Horaforo tribe in New Guinea have been thus described by Dr. J. Coulter:—"Against each tree rested a notched pole, and at a whistle from the chief, answered by hundreds of similar sounds in every direction, natives with flambeaux flitted down the poles till the whole forest was brilliantly illuminated. In fact, they had their houses, or rather nests, in the trees, and when they retired for the night the pole was hauled up to prevent surprise. These abodes were made by thinning away some of the branches, and laying horizontal poles on others sufficiently stout to bear them; the uprights are cut with forks, which rest on the lower branches, while their upper ends are lashed with cocoa-nut fibre to those above; the sides are formed by bamboos lashed closely together; the roofing is also of cane covered by sheets of thick bark sewed together, and perfectly proof against the heavy rains. The flooring is laid with split bamboos and light wood, and the walls are lined with stout matting, which gives sufficient shelter against the piercing winds. The shape varies according to the spread of the tree; sometimes when they extend all round an extensive house is made to inclose the whole tree; the smallest will measure 16ft. square, but sometimes they are longer and less wide; and when the whole tree is built in they are three times as large. They are perfectly safe, for the lower branches are as thick as an ordinary tree.”

The lodges of the North-American Indians are perhaps the most convenient residences which could be devised for people of their nomadic habits. The lodge poles, or supports, are made from tough durable wood, well-grown young saplings being selected for the purpose. On the line of march they are, by fastening them to a sort of pad, secured on each side of a horse, or even dog. The ends trail on the ground like the skids of a sledge, and are packed with various odds and ends, which are prevented from falling off by cross-bars and a lashing of hide or twisted bark rope, as shown in the full-page illustration. When the camp is about being formed, the poles are freed from their attachments and set up in a circle, forming an irregular cone, the apex of which consists of the converging and collected ends of the poles, through which the smoke escapes. The lodge covers are made from prepared skins, on which are depicted, in rough outline, some of the most noteworthy achievements and events in the life of the owner. The lower borders of the skin covers are secured to the ground with pegs, whilst thongs are made use of for binding the poles in places and uniting the skins. The tracks of the trailing lodge poles in the sand, or across the plains, may be looked on by the traveller as peaceful indications, as, where the lodge gear is, the squaws and papooses will be found. On the war path all such impedimenta are left behind in some place of safety.

Water, in fact, unless kept in constant agitation, loses its fluidity. A sheet of ice is as dry as a piece of glass, and snow seems to have no more moisture in it than the dust of the highway on a Derby day.

Owing to this quality snow does not accumulate on small surfaces elevated and exposed to the wind. Captain Parry found that from the roof of his vessel a fresh breeze invariably carried off any snow that had settled on it in calm weather, and also from the masts, yards, sails and rigging. His opinion is that in high latitudes the less the ship is dismantled the better, for the frost does not hurt the gear, and no harm can occur from thawing till the season for refitting arrives.

Should you at any time be so situated as to be compelled to winter on board ship in the Arctic regions, it will be well to follow the plan pursued by Dr. Kane to render his ship and cabin as cold proof as possible. He procured large quantities of moss and turf, with which the quarter-deck was thickly covered. Down below he inclosed a space about 18ft. square, and packed the walls forming it, from floor to ceiling, with the same materials. The floor was carefully caulked with plaster of Paris and common paste, on this was laid a stratum of Manilla oakum 2in. thick, and over this deposit a canvas carpet was spread. The entrance was from the hold, by a long moss-lined passage or tunnel, formed after the manner in which the Esquimaux arrange the “topsut,” or rabbit-burrow like passage which leads to their huts, as shown in the illustrations at pp. 313 and 315. A number of doors and curtains were then constructed at such points as afforded a chance for the ingress of cold. This moss nest, or den, was constructed to accommodate ten men.

The outside of the ship was banked up with moss, and over that a thick bank of snow was made.

The snow, indeed, when lying in proper thickness, and sufficiently compressed, forms the best possible material for building. Cold as it is in itself, it seems to act as a non-conductor of heat; and if an internal structure, however slight, can be set up, the thicker the outer wall of snow is made the better. Captain Parry’s men proceeded in the following manner: In banking the snow against the ship’s sides, a wall of sufficient height was built about 4ft. from them, and loose snow was thrown in till it covered nearly the whole of the upper works; about 8in. of snow was also laid on the decks and hatches, and above this a layer of sand cemented by water, for the double purpose of preventing the escape of heat from below, and saving the planks from being rifted by the frost; and the waste heat of the galley fire was utilised by making the funnel pass up through a tank, which was kept filled with snow, thus without any extra fuel producing 65galls. of water per diem. A wall of snow, 12ft. high, was built at a distance of 25yds. all round the ship, to afford a comfortable shelter from the wind. It is also essential to make and keep always clear of ice a ‘fire-hole,’ from which water can be procured at any moment in case of need.

The observatory was built on shore: first of planking lined with canvas, with a layer of turf outside, and completed by an extra thickness of solid slabs of snow; it was flat-roofed, and as small as possible, the instrument room being 8ft. square, and the working room 5ft. by 8ft., thus economising either natural or artificial heat. In fact, it seems that the primary object in building a house is to make the actual dwelling room as small as possible, and the passage to it so long and narrow, that it requires almost a long journey to reach the external air. Dr. Hayes describes a snow house, or rather cave, dug by an Esquimaux in a snow drift that had collected in a sheltered hollow. He dug downward first about 5ft., then horizontally about 10ft. more, tossing the detached snow blocks out behind him, and then began to excavate his cavern, to which, when finished, he built a doorway just large enough to crawl through. The floor was covered with a layer of stones, and then with several layers of reindeer skins; the walls were also hung with skins; two native lamps lighted, a skin hung across the doorway, and he and his family were “at home,” the temperature soon rising to the freezing point.

The doctor’s temporary encampments were thus formed: A pit is dug 18ft. long by 8ft. wide and 4ft. deep; over the top are placed the oars to support the sledge; over the sledge is the boat’s sail, and on that is thrown loose snow. In one end of this den is a small entrance hole, closed with blocks of snow; over the floor is a strip of india-rubber cloth; over this two buffalo skins, between which the whole party of twelve pack themselves as closely as possible, the only change of costume being to take off the boots and stockings and replace them with sleeping hose of reindeer skin. A pot of hot coffee, or a hash of dried meat and preserved potatoe, cooked over a lamp of oil or alcohol, forming the repast, of which the most estimable quality is its warmth. Captain Parry, being rather surprised at the short time in which an Esquimaux village sprung up near the vessel, induced some of the natives to build a hut, and found that two or three hours were enough to complete the establishment. The only materials are snow and ice, the latter being only used for windows. A number of slabs of compact snow, 6in. or 7in. thick and 2ft. long, are cut and laid edgewise in a circle, on a level spot, covered with snow, from 8ft. to 15ft. in diameter; on this is a second tier, sloping a little inward, each slab made to fit closely by running a knife along its edges, the top is then smoothed off with the knife, and the builder, standing in the centre, receives the slabs for the successive tiers from the men outside. When the walls are 4ft. or 5ft. high they begin to lean inward, so that it appears as if the blocks laid on them would fall; but the workman still goes on raising and closing in the hemispherical walls, and when they have become too high for the slabs to be handed over to him he cuts a hole at the bottom with his knife and has them passed through. The dome is often 9ft. or 10ft. high, and it is carefully finished by the men outside dropping the nicely rounded block that serves as a keystone, to be received and fitted by the man within. The outside workers heap snow round the foundations, and carefully stop up any accidental holes between the blocks. The builder lets himself out by cutting an arch 3ft. high and 2½ft. wide, and from this they construct two passages—end to end—each 10ft. or 12ft. long and 4ft. or 5ft. high, the lowest being next the hut, as shown in the outline ground plan. The roofs of these passages are sometimes arched, and at others covered with flat slabs.

If a single apartment is required the hut is now complete, but if several families are to reside together the passage is made common to all, the first hut becoming a kind of antechamber, and is commonly a little smaller than the rest, which are entered by arched doors 5ft. high. Sometimes the ground plan assumes the form of a cross, as in the instance we now illustrate. A hole is cut into the side of each compartment, and a circular plate of ice 3in. or 4in. thick, and 2ft. in diameter, let into it. The light is like that transmitted through ground glass, and is quite sufficient.

The fireplace is a shallow vessel of stone, the wick is of moss rubbed dry between the hands, disposed along the straight edge for about 18in., it supplies itself from a long strip of blubber hung near enough to be melted gradually, and drop slowly into the hollow of the stone; over the lamp is a network, on which wet boots or mittens are usually laid. Frequently there are two other lamps in the corners next the door, for no married woman or widow can be without her separate fire.

With all the lamps lighted, and the room full of people and dogs, the thermometer on the net over the fire stands at 58°; 2ft. or 3ft. away it falls to 32°, close to the wall it is 23°, the temperature of the open air being at the same time 25° below zero. If the temperature is raised higher than this, the melting of the roof causes great inconvenience; but when an inclination to drip is observed, a patch of cold snow is plastered on to absorb the superfluous heat. In the time between the extreme cold of winter, and the season when it is possible to live in tents, the natives suffer much from this melting of their walls.

The cooking is done in pots of hollowed stone (lapis ollaris), slung over the lamps. Many of these are cracked, but are joined by lacings of sinew, or rivets of copper, iron, or lead, which, with a sufficient coating of dirt, makes them again watertight. Their knives are sometimes of ivory, but the best are of iron, obtained from the Hudson’s Bay Company.

They procure fire by striking two pieces of iron pyrites over a leather case with dried moss in it, and a little floss from the seed of the ground willow helps to convey the flame to a bit of oiled wick—sometimes the wick for the lamp is made of asbestos.

At times, especially in the commencement of the winter, the huts are built of ice instead of snow. They approximate to a circular form, but from the flatness of the material necessarily present a number of flat sides and obtuse angles. They are cemented entirely with snow and water, and roofed with skins, which are replaced by snow as winter advances. The entering tunnels are also of slabs of ice, as are the kennels for bitches and puppies. The skin canoes are propped up on slabs of ice high enough to be out of the reach of the dogs. The semi-transparency of the walls give these huts a strange effect, and some of our later voyagers have called them crystal palaces; but all the purity, either of ice or snow, disappears, and whatever cleanliness the Esquimaux possess is forced upon them by the annual thawing of their houses.

The summer tents are made of several seal or walrus skins, the former without the hair, and the latter with the thick outer coat taken off, and the rest shaved down so thin as to admit light through them. They are irregularly sewn together, forming a kind of oval bag, supported in the middle by a pole of several deers’ horns or bones of other animals lashed together. On the top of this is a cross or T-piece, which serves to extend the top of the tent, 6ft. or 7ft. from the ground the lower part of the tent pole rests loosely on a large stone, from which any accident will knock it off. The borders of the skins are kept down by stones laid on them, and the top is stayed by a thong on the outer side, stretching to a heavy stone at some distance. The door is merely two flaps, one of which overlaps the other, secured by another stone.

Sometimes a little shelter from the wind is given by an outer wall of stone.

If a larger tent is required, two of these bags are made to overlap at the edges, and are set up with a couple of poles.

The accumulation of seal and walrus flesh and blubber during the summer months makes these habitations disgustingly filthy; but it is to be remembered that the great necessity of the Esquimaux is to keep himself warm, and he cannot afford to lower the temperature of his skin by washing off the grease and dirt which encrust it.

On one experimental trip Captain Parry was compelled by a sudden decrease of temperature to shelter his party in a small tent. They attempted to warm themselves by smoking, and found the temperature at their feet to be 1° below zero, while overhead the smoke had raised it to +7°, the outer air being -5°, soon falling to -15°. It was then found possible to dig a kind of cavern in the snow, the spade being lent as a favour to the men who most required to warm themselves, a small fire and a pot of soup were made, and by confining the smoke and hot air the temperature was raised to +20°, while outside it was -25°.

CHAPTER V.
EXTEMPORE BRIDGES AND MAKESHIFTS FOR CROSSING
RIVERS OR RAVINES.

The solitary traveller in a wild country will be very rarely compelled to construct his own bridge, for, as a general rule, he will only have to pass once, or at most to return by the same route. The labour of making a bridge would be greater, and more time would be lost, than by seeking for a practicable passage at some distant point, or, in case a river was the impediment, forming a float of some kind.

There are, however, occasions when there is no alternative but bridge-making, as when exploring expeditions, accompanied by pack animals, or a field force on the march, have rivers, swamps, ravines, or, perchance, rotten ice, to pass over. Where there is not water enough to float a canoe, but where there is sufficient to cause the formation of deep pools and dangerous mire, over which few animals used for the conveyance of baggage could pass without the aid of some artificial footway, narrow deep channels may be very often rendered comparatively easy to cross by filling them up with bundles of brushwood or marsh reeds. We were constantly in the habit, when engaged in making forced marches through Central India, of making use of the stalks of the recently cut juhari for this purpose. Unsafe ice can be rendered firm and secure by strewing a thick layer of reeds over it, and then throwing water enough to cause the whole to freeze into a compact mass.

Before, however, proceeding to describe the various modes usually had recourse to for rendering trees available for bridging purposes, it will be well to give a few plain and practical directions for ascertaining the width of rivers, ravines, and the arms of swamps, without the aid of scientific instruments, and also for finding, by makeshift modes, the altitude of trees.

To find the Width of a River without Instruments.

Fig. 1. If you have a pocket compass, and the river runs, say east and west, and you are on the south side, choose a well-defined tree, A, or other object on the opposite shore, and bring it to bear north of you; mark your position by putting in a stake or peg, B, turn to one side, say the left, and walk westward till A bears north-east, which will be the case at C; then C B will be exactly equal to B A, or the breadth of the river, because from the point C, A will bear north-east, and B will bear east, subtending an angle of 45°, and as the line C B is east, and B A is north, they subtend an angle of 90°, or a right angle, and must be of equal length; the triangle you have formed being the half of a square, divided by a diagonal line from corner to corner.

If you have room repeat this by walking east till A bears north-west from D; and if the first operation has been correctly performed, the second will confirm it; or if the first be in error, it is likely that the second will be exactly as much in error the opposite way, and the mean of the two observations will be approximately correct.

Fig. 2. If you have not a compass, choose A as before, set in a stake at B, and prolong the line to C; then on this line erect a perpendicular by looping a cord on the stake at C, and with a sharpened peg held at the other end of it drawing the arc, D E; then, making D and E equidistant from B, draw through these three points the line D B E F; on this line retire toward F till A and B form an angle of 45°, which may be measured either by folding a square of paper diagonally, or by pegging out a piece of string divided into two lengths of 24in. and one of 32in. See that the longest or diagonal side bears truly upon A, and one of the shorter sides on B, which will take place at the point F, then F B will be equal to B A, or the breadth of the river. Repeat this also if the ground allows, on the opposite side G, and take the mean of the two observations.

The correctness of all these observations may be greatly increased by resting your rifle on each successive point, and carefully sighting all the lines with it.

Fig. 3. Another excellent and simple plan is—choose A; set in B; from B erect the perpendicular B C, C D, divided equally at C; from D erect the perpendicular D E; retire along it till the stake C bears truly upon A, which will be at F, then F D will equal B A.

Fig. 4. If the river bank is so curved that you cannot draw B C D at right angles, you have two alternatives. If there is plenty of room retire as far as you please from the bank before planting the stake B, and deduct from the result the distance you retire from the bank. Or, if there is not room, you may draw B C D, as in Fig. 4, diagonally, and contrive to keep D E as nearly parallel to A B as you can; but any defect in parallelism will greatly affect the correctness of your measurement, as will be evident from the dotted line G.

Fig. 5. If the river is wide, choose A as before; set in B, and retire any measured distance, say 6yds., to C; then from B and C erect perpendiculars of equal length, and draw the square B C, D E; test it by stretching a cord from corner to corner; then, prolonging the line C E, bring the stake D in one with A, and produce the line A D till it intersects C E at F; then divide F E into six parts, measure as many of them as you can on the line E D, and you will find as many of them as there are yards on the line B A; therefore, in the present instance, 11yds. will be the breadth of the river, and one may be deducted because the marks are not close to the edge of the banks; or say, as E F is to E D so is B D to B A.

Fig. 6. To erect a perpendicular on a given point on any line, measure equal distances on either side; set in pegs, loop a cord on them alternately, and strike two arcs, their intersection will be perpendicular to the given point. To cross the end of a line by another at right angles, set a peg some distance back, loop a cord on it, and strike an arc. Measure equal distances from the end of your given line to the arc, then a line drawn through the three points will be at right angles to the first.

A scale of equal parts may be made by folding a slip of paper in half, then folding each part in half, and so subdividing it as much as you wish, but do not fold it in half, and then double the two parts to get the quarters at one operation, and then double the four parts to get the eighths, or you will find them come out very unequally.

A measuring tape may be made by taking a narrow white tape, say ¼in., and winding it on a slip of card barely an inch wide, just so little spirally that each turn may not half cover the preceding one, then carefully blacken the edges, and, when you unwind the tape, mark every twelfth inch with figures to denote feet, and every sixth with an extra line.

A square is made by taking a sheet of paper, folding the corner down so that the edge of the end coincides with the edge of the side, and then cutting off the superfluous length, each corner of the square is an angle of 90°, i. e., a right angle or a quarter of the compass, say from north to east. The diagonal fold makes at each corner an angle of 45°, or four points of the compass, say from north to north-east; fold this again, and it will give 22½°, or two points of the compass, from north to north-north-east, and this may again be subdivided if needful.

We have often tried the breadth of rivers by firing a rifle ball at some well-defined mark on the other side, with the sight adjusted to 100yds. or more, according to the estimated distance, and noticing whether the ball reached beyond or fell short of the mark. The habit of doing this very greatly corrects and assists the eye in forming estimates of distance. A good stone thrower ought to know the range he can make with pebbles of different sizes. If a native is near buy one of his least valued arrows or spears, and get him to throw it across, and then ask him to throw a similar one on ground where you can recover it and measure the distance, but never ask a savage to throw away weapons of the chase for nothing. In calm weather, we have fired a rifle ball, with its utmost range, on the surface of a lake, and have counted seconds from the time we saw the splash till we heard the sound of its fall. Sound travels 1142ft. in a second, or about a statute mile in 4¾ seconds, or a geographical mile—or rather one minute of latitude, or of longitude on the equator—in 5¾ seconds.

To find, without Instruments, the Height of a Tree or other Object, whose Base is accessible.

Fig. 1. Fold down a square of paper from corner to corner, and you will obtain a triangle, of which two of the sides form a right angle, and the third, or diagonal, forms an angle of 45° with each of them (see next page). Make a mark upon the tree 5ft., or the height of your eye, from the ground, and retire from the tree till, holding the paper steadily with one short side horizontal and the other vertical, you can take sight along its lower edge at the mark, and along the diagonal side at the topmost branches; then pace or measure the distance from the tree, add 5ft. for the height of the eye, and you will have the height of the tree; because, if the two angles of the diagonal be 45°, the base and the perpendicular must be equal. A piece of thin board, with pins set in at each angle to serve as sights, would be better than the paper, but is not so readily extemporised. If you split the end of a wand so as to hold the paper or board quite up to the height of your eye, it will give additional steadiness. The observer in our illustration is unavoidably represented a little too near his work, but he is probably taking the height of the first bifurcation, which is often more important than the height of the tree.

Fig. 2. Or, sticking a branch into the ground, select one of its forks, or lash on a cross piece which shall pass through the trigger guard behind the trigger, so that the gun may be about the height of your eye when you aim horizontally at the mark on the tree, the trigger finger grasping the stick for greater steadiness. Take another stick, with a fork or cross rest of equal height with the first, and connect them by a smaller stick of any length, say 18in. or 2ft., and at exactly the same height above the lower rest lash another on the second stick, so that, the base and perpendicular being equal, the gun, when its muzzle is laid on the higher rest, shall form exactly an angle of 45° with its line when previously laid upon the lower one. Now retire until from the lower rest you can sight the mark upon the tree, and from the upper its highest branches; then the distance from your pivot stick, plus 5ft., will be the height of the tree. Our illustration purposely shows this operation in the simplest possible form; but the frame might be steadied by lashing on other cross bars (X fashion), and a friend to help in moving it to a greater or less distance from the tree would greatly assist the observer. It would be inconvenient to make this observation kneeling. A telescope, a long straight reed, a roll of paper, or a straight tube of any material, will answer almost as well as the rifle. Fig. 3 Even a clasp knife (Fig. 3), with a bit of reed stuck into the handle where the point should reach, and resting on the point of the half-opened blade, is better than nothing.

If the ground is perfectly level, and you have a looking-glass, lay it down and level it by setting on it a basin full of water; retire till you see the top of the tree reflected in it, then if your distance from the mirror equals the height of your eye, the distance from the mirror to the tree will be equal to its height. In perfectly calm weather the basin of water will do without the mirror, or a shallow pool or river will give an approximation; but, as the ground is always depressed where water settles, there will be some uncertainty about the height of the eye, which will more or less vitiate the observation, and this will also be the case if thirsty animals rush in to disturb it, as in our sketch. Or if the sun or moon is shining, set up a stick, and watch till its shadow is equal to its height, or note when your own shadow equals your height, and the height of the tree and the length of its shadow will also be equal. But, as it may not be always convenient to wait for this moment, the height of the tree may be found by proportion. If the stick is 5ft. and its shadow 7ft., then if the shadow of the tree be 70ft., its height will be 50ft.; or if in looking at its reflection in the mirror, the height of your eye be 5ft., and the distance 8ft., then if the distance from the mirror to the tree be 80ft., its height is 50ft. In either of the first two methods the same rule must be observed; the paper may be folded to a greater angle if you cannot get far enough from the tree, or a smaller one if you must go farther, and the same with the elevation of the rifle. In these cases, carefully measure the base and perpendicular of your smaller angle, and say, “as the base of the small angle is to its perpendicular, so is the distance from the tree to its height.”

Thus, as in Fig. 4 on next page, if the distance between the two rests is 2ft. and the elevation of the rifle 1ft., the distance from the tree must be equal to double its height.

All these observations will apply to any object of which the highest point is perpendicular to the accessible base, such as a precipice, the wall of a fort, or the gable end of a house, but not to the peak of a mountain, two or three miles beyond its base, nor to the pitched roof of a house seen sideways, nor to the spire of a church, or flagstaff on the central tower of a castle, unless the doors of these buildings be opened so that you can continue to measure your base to a point exactly beneath that which you have taken the angular height. Still, if the base be not accessible, it is not impossible to measure the height, for the distance of the object may be taken by any of the plans for ascertaining the breadth of a river, or any of the above methods may be performed twice over, as in Fig. 5; computing distance from 2 pointsfirst, at any convenient distance, b, and secondly, at a measured distance, c, nearer to or farther from the object; and the easiest way of obtaining the result is to lay down on paper the obtained angles, d, e, f, and g, h, i, in due proportion to the measured distance, b, c, between them; then from them to protract the angle, d, g, a, and continuing the base line, find on it the point j, from which a perpendicular would meet the top of the object, a. The distance, b, c, being known, that of the base, b, j, and the height of the tree, j, a, will be best found by measurement of equal parts, but bear in mind that the result can only be an approximation to truth, for every additional operation involves an increase of possible error.

In passing extensive marsh tracks, few expedients surpass the so-called American cordway, the subject of the illustration on p. 325. It is constructed as follows from the description of material usually abounding in marsh tracks: Trees and poles of almost any description will be found to answer. Cut as many as is thought requisite. Divide them into three classes—ground poles, cross poles, and stringers. The ground poles should be the largest and heaviest. The cross poles are comparatively short lengths, and lay across the ground poles with their ends projecting some distance beyond. They are laid closely together, and then secured and bound down by the stringers which lay on them. A treenail driven in here and there serves to keep all in place by nipping the cross poles tightly. The ends of the ground poles and stringers may be either scarfed and treenailed, or laid side by side and tied with withies or strips of suitable bark. It will be seen, on examining the illustration, that where the roadway ends a bridge begins. This is of the description known as a one-tree bridge, and is made as follows: Select a tree of sufficient length to reach, when felled, across the stream, and of fair average girth, say 9ft.; fell it with the axe in the manner before directed, and then walk out on the trunk and cut away all the branches from the upper surface; then log it up into lengths of about 10ft. a sufficient number of transverse pieces to reach, when placed side by side, from one end of the bridge log to the other. Then in the centre of each of these make a shallow notch by delivering right and left cuts with the axe. Next with your auger bore two holes as wide apart as the diameter of the bridge log will admit of. Lay your transverse piece on the main log, so that it shall rest in the form of a true cross, with the notch in the centre resting on the main log; then, whilst keeping the cross piece steady with one foot, bore down the auger holes about a foot into the solid timber. Treenails (see “Treenails, to make”) are then to be placed in the holes and driven home with a mallet or the head of the axe.

Another form of tree-nailed bridge, calculated for very wet or dangerously swampy ground, is formed by laying down two lines of stouter ground logs than those used to form the “cordway” just described, scarfing and tree-nailing the ends together as they are laid down. The transverse bars for the footway have a right and left chip taken out each end from the surface which is to lay next the ground log. They are then bored with the auger, one hole at each end being sufficient. They are then placed closely side by side. One man completes the hole which passes down into the log, whilst another drives home the treenails, as shown in the annexed illustration. Earth or sand thrown with a shovel between the cross pieces increases the stability of the arrangement. Treenails, to make. Treenails have been, and will be, frequently mentioned in the course of this work; it will, therefore, be well here to give directions for making and using them. To the shipwright they are invaluable, as by their aid he unites the various planks and timbers made use of in the carrying out of his art. In England they are usually made from straight-grained oak, which, after being sawn into proper lengths, is split up into the rough form of the required treenail. This, after being faced and hewn with the adze, is passed through a double-handed cutting instrument known as a treenail tool. A skilfully-handled axe, a spokeshave, or a drawing knife, will, although less expeditiously, produce with ease well rounded and serviceable treenails. In wild countries any tough straight-grained wood may be selected for treenail making. For bridge and roadway work pine wood will answer the purpose very fairly. A dead log is best when it can be obtained for making these wooden holdfasts. Cut it up into pieces the length of the proposed treenail, chop off the bark, and split them into either three or four (as directed at p. 272), according to the size of the log; then, with the froe or axe, split them into rough squares the length of the required treenail, round off the curves and corners, chop off the edges at the end, so that it may enter the auger hole freely, and the treenail is ready for use.

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.