outdoor living » the 10 bushcraft books » travel & gear (pt. 1)

.introduction

It may be necessary to travel through unknown country, and this, without map, compass or any equipment. Under some conditions the traveller may have been totally unprepared and on his ability to travel and arrive may depend his ultimate survival.

In this book a little known or used ability of the eyes to stereoscope aerial or other pairs of photographs, and view the subject in true three dimensions, unaided by any optical equipment, has been included. Under some conditions this knowledge may be useful.

Apart from this, the exercise itself is a valuable and exciting experience in the use of the eyes.

There are many suggestions in this book that will provide real opportunities for adventure, which could be simply doing ordinary things differently.

Travel and gear is of necessity directly associated with Time & Direction, book 10 of the series.

.maps

Before you set out on any journey through the bush you must have a map of the area or else you must make one as you go along.

A map is a plan of a section of country. Being a plan it is drawn to a scale or proportion, and thus is nearly always shown prominently, generally at the foot of the map. As a plan it should also show either TRUE North, MAGNETIC North, or both, which by convention is generally at the top of the map. Unfortunately this useful convention is not always followed, and therefore you must check your map if the North is not shown. If it is not marked you must add this essential information. Show TRUE North as a strong line and MAGNETIC as a dotted line and mark each, so that anyone else using your map will know the difference.

Being a plan of a section of the country, your map will show ground features such as rivers and mountain ranges in relation to one another, and it may show man-made features such as buildings, roads and railways.

.aerial photos

An alternative to a map is an aerial photograph of the country, or better still, aerial pairs of photographs. To read either an aerial photograph or aerial pairs you must learn to hold them correctly.

With aerial photographs but not necessarily with aerial pairs, the shadows must fall towards you as you look at the photograph.

If you hold an aerial photograph upside down, that is with the shadows falling away from you, you will almost certainly read hills as valleys, and vice versa.

Aerial pairs if looked at stereoscopically must be looked at in a special manner, but if a single one of an aerial pair is being studied, it must be viewed with the shadows falling towards you. This is important.

In this aerial the shadows fall towards you, and you can "see" the mountain ranges. Turn it upside down, now the hills become valleys, and the valleys hills.

An aerial photo can give more information than is commonly given on a map, but you must be specially skilled in reading the photograph, and it takes a real expert to look at a photo and say, "That is ploughed land, and that is forest land, while that is grass country".

The texture of the earth's surface photographed tells the story to the eye of the expert.

.stereoscopic vlewing of aerial photos

This is true too of aerial pairs. These are photos taken hundreds of feet apart while the plane is flying several thousand feet above the ground. When looked at stereoscopically the mountains and the valleys show form in full three dimension. You can stereoscope these pairs with your eyes alone, unaided by any mechanical means, provided you have two points of vision, that is provided that there is equal or nearly equal vision in both your eyes. The stereoscopic effect is obtained by making each eye see a different image.

The easiest way for you to do this at first is to roll two pieces of paper into tubes about 10" [25 cm] long and 1" [2.5 cm] diameter. The exact size is not critical.

Put one tube to your left eye, and place it a few inches over the left eye picture (see the last paragraphs of this section to know how to recognise the left eye picture and right eye picture). Now place the other tube to your right eye, with the other end of the tube a few inches above the right eye picture. The two pictures must be side by side, and identical spots on each picture must not be more than 3" [7.5 cm] apart.

Each eye will see a different image, and with a slight exercise that feels rather like "crossing your eyes" you will see the two pictures merge together, and by concentrating on the single image when they come together you will suddenly see it become fully stereoscopic. (Try and bring the two black dots on each picture together.)

Correctly paired.

Incorrectly paired.

This is an eye exercise which at first will make your eyes rather tired, but keep it up. The exercise is good for your eyes, and soon you will be able to look at a pair without tubes and fuse the two images instantly. Try it with tubes on these two pictures. The photo is of a mountain gorge in Dutch New Guinea.

When you have trained your eyes to see each image through the paper tubes you can take the tubes away, and hold the stereoscoped image in your vision.

In stereoscopic use of aerial pairs you must know how to recognise right eye from left eye pictures. If by chance you reverse the images the mountain crests will be deep craters, and the valleys will be ranges. Here is the same stereoscopic pair reversed, viewed stereoscopically you will see this happen.

Note too that in reading stereoscopic pairs it is not necessary for the shadow to fall towards you.

.recognition of right and left stereoscopic pictures

To discover which is the left eye image select two identifiable points similar in each photo of the pair. One is the black spot on the line YY crossline 1 on the end of the mountain range, and the other is the white spot to the right where the little river joins the main stream on the line XX crossline 2.

One of these points must be on what would be one of the points of highest elevation of the land, and the other on one of the lowest elevations. The two points must be as close to a vertical line as practical. The parallax will show you which is the right and left eye image. In the left image Y and X are closer than in the right image.

Explanation: The parallax is the angle between the point nearest to and the point farthest from the camera. Compare this with same photos reversed in the second photograph pair. Notice the space between A and B in both photos. In the left image A and B are further apart than in the right image.

The two pictures must be equal in density of print, and must be placed side by side to be viewed. The maximum distance between two points for comfortable stereoscopic viewing with unaided eyes should not be more than 3" [7.5 cm]; by straining you may be able to fuse separations 4" [10 cm] apart.

Note: You can make three dimensional pictures with an ordinary single lens camera by taking two pictures from different positions with exactly the same exposure and aperture. The distance between the two positions is governed by the distance of the nearest object in the foreground from the camera. For every 30' [9 m] the nearest part of the foreground is distant there should be not less than 9" [22.5 cm], and not more than 12" [30 cm] separation in position.

.route from aerial photo

When deciding a route from an aerial photo, or from an aerial stereoscopic pair which you have stereoscoped it is essential that you mark the TRUE North on the photo and also determine a scale. The scale will probably be approximate, but it should be sufficiently close to give you not more than half a mile [0.8 km] error per five miles [8 km] of travel.

It is also advisable to prepare a route or sketch map based on your study of the aerial photo or pair. If you do this you will work to your sketch map, and only refer to your aerial when some point of doubt arises.

.logging your route, and making a chart

A log is a record of the essential information of your journey. This information must include distances and bearings, and may include any other information which the log writer considers helpful to himself or others.

Distances for log making in cross-country travel are calculated from the factors of rate of travel, and time.

Rate of travel varies. On open undulating country with short grass underfoot a walker will average a mile [1.6 km] in between seventeen and twenty minutes, but in steep rocky country overgrown with scrub and thick growth underfoot a mile [1.6 km] in sixty minutes might be good speed, and I have known places in New Guinea where one had to cut one's path through thick pit-pit (a giant grass up to 12' [3.6 m] high) and there a mile [1.6 km] forward would not be made in eight hours.

The following table may be considered a fair guide to walking paces. Remember there is a tendency to overestimate rate of travel.

These figures are for an active man laden with a 30 to 40lb. [15 to 20 kg] pack. With heavier loads the maximum time would apply.

Rate of progress can be checked by each individual walker for himself. He can assume that 110 paces equal 100 yards [metres], on level walking, and by multiplying the time to walk 100 yards [metres] by 17½ he will have a very accurate indication of his walking speed per mile [multiply time to walk 100 metres by 10 to get walking speed per km].

In climbing or descending rocky or broken ground his pace will be very much shorter and slower, and the walker will take about 150 to 170 paces (depending upon slope) to equal 100 yards [metres]. On very steep slopes there may be 200 paces or more per 100 yards [metres] of lateral distance.

Time of course can be obtained from your watch, or, failing that, from your sun clock - sun compass (previously drawn on your map) or drawn on the piece of paper on which you are keeping your log.

A log is kept most easily by recording the information in vertical columns.

This information is later plotted, and in this form it becomes a chart of your route.

With this chart plotted you are never lost, because you always know where you are in relation to the point from which you started. It was in this manner that early explorers recorded their routes into unknown lands.

.choice of route

Given a free choice it is always advisable in cross-country travel to choose a route up spurs and ranges and down streams, unless in very mountainous country. By following this principle there is less likelihood of getting lost for the simple reason that all spurs lead to the main range crest, and all streams lead to the main river course. By travelling down spurs, or up rivers it is very easy to take the wrong spur; or follow the wrong watercourse and so in a few miles to find oneself hopelessly bushed.

This applies to country which is sparsely populated. Therefore before setting out across country it is advisable to carefully study your map, and plan your route, remembering all the time the general rule to choose if possible, a route up spurs and down rivers.

This sketch map will show you how very easy it is to get "bushed" by either travelling down a series of spurs, or up a watershed. The wise bushman, wishing to go from A to B, will go by the route C rather than by the route D.

You will find these alternatives are often presented to you in cross-country travel.

.map reading

While many maps show man-made features such as prominent buildings, roads, railways, and canals, it is advisable to read the ground shape of the land and not place too much reliance on man-made works. The surface of the land will never change, but man-made constructions may vanish.

The most obvious natural features are ranges and rivers. The ranges may be very steep, or gently sloping, and to show this map makers either use 'contour' lines or hatchuring.

Contour lines are imaginary lines parallel in height and with an equal height separating one height line from the next. By correctly reading contours on a map you can tell if one hill is convex or concave in its slope. If concave, you can see the bottom of the hill from the top, unless of course intervening vegetation limits your visibility. With convex slopes you cannot see the lower grades because the curvature of the slope cuts off your field of vision.

The end of the spur in top left position of the map shown is a convex slope, and the slope east from the hill bottom centre is a concave slope.

A convex slope shows the contour lines closer together at the foot of the hill, and wider apart at the top, while a concave slope shows the contour lines farther apart toward the lower slopes.

Position on a map is always given by a map reference. These are a series of numbers which indicate the square referred to. You will see in the top left corner of the map (Fig. 1) numbers reading vertically and also other numbers reading horizontally. These numbers are always shown on military maps, which you are more likely to use than others.

The vertical figures indicate the longitude (shown as 147 degrees 15 minutes), and the other figures 976,000 are the number of yards from the 'base line' of that section of country. Reading to the right from the top left corner each smaller square is indicated by the last two THOUSAND numbers, 77, 78, etc. Each square is 1000 yards (unless marked otherwise - see the map scale for this information). The same rule applies to the horizontal numbering; on this column is shown the latitude of the line (in this case 34 degrees 50 minutes south of the equator). Map references are read from west to east first and from south to north, so that the figures 78.58 mean that you look along the grid line 78 until you find the square starting 58, and the reference is within that 1000 yard square. Each thousand yard square is divided again into ten smaller squares, each of which is 100 yards. This gives a six-figure reference 782.583. and you will find that this is the fork of the creek in the third square second row from the bottom.

Now see if 806.584 is the top of a hill?

Map reading when done correctly allows you to build up in your mind a picture of what you could see from any given position. If you were on the spur at A 768.632, could you see the position B at 858.572? In the lower diagram (Fig. 2) the elevations between A and B have been plotted. The tongue of hill running north-east through 81.59 and 82.60 would interrupt your view of B from A.

A military map also shows you a 'legend,' which are symbols indicating vegetation, water, and roads, etc. This is generally given at the foot of the map, and assists you in building up in your mind a complete picture of the country.

Hatchuring, instead of contour lines, is used by some map makers to give an indication of the nature of the country. Fig. 3 would be a hatchured map of the same country shown in Fig. 1. In hatchuring thick strokes close together indicate very steep grades, while thin strokes far apart indicate gentle slopes. In many European maps the hatchurings are definite, thick strokes very close together might mean a slope of 1 in 2, to 1 in 3; thick strokes farther apart a slope of 1 in 4 to 1 in 6; thin strokes close together 1 in 8 to 1 in 10. These of course may be also expressed in degree of slope (1 in 56 grade equals a one degree slope).

.the sun compass - sun clock

[Get you hands on a simple Sun Compass/Clock generator here.]

Direction and time can both be obtained by drawing a sun compass - sun clock on your map. Trace off the illustration for the latitude line nearest to your map, and it will be both a compass and a clock for you. With a sun compass - sun clock, when you have any one of the following you can discover the other two.

1. A watch to get correct time.
2. A reliable compass.
3. A map correctly oriented (that is laid in the ground so that the features drawn on the map correspond exactly with the recognisable ground features).

When You Are Able To Orient Your Map Correctly

The north-south line of your sun compass will correspond with the north-south of your map, and your time is read and corrected as explained in the instructions below.

To orient your map select two, or better, three, recognisable land features, and identify these on your map, Turn your map until the identified features exactly correspond in direction with the ground features. When this is done your map should exactly fit all the ground plan visible from your position.

When You Have A Watch Set To Correct Time

Place a thin shadow stick on the centre line of the sun compass which must be held flat, opposite the appropriate date, and turn the map until the shadow falls across the adjusted time on the latitude line.

When you have done this your map will be set to TRUE north, and oriented with the ground features.

When You Have A Compass

Place your compass on the map with its axis along TRUE north line, and turn both map and compass till the compass needle is pointing to the MAGNETIC north of your map. (This may be east or west of TRUE north depending where you are.) The magnetic variation is shown on ALL Ordinance Survey (Military) maps.

When you have done this, hold the shadow stick on the north-south line of the sun clock opposite the appropriate date and where the shadow of the stick falls across the latitude line is local sun time.

To correct to STANDARD or CLOCK time make the correction for the equation of time shown opposite the date, and also the correction for longitude by deducting four minutes for each degree you are east of the longitude of standard time [i.e. the longitude your time zone is based on, see here], or adding four minutes for each degree you are west. (When east of the longitude or standard time the sun is earlier, and when west the sun is later.)

When the magnetic of your compass exactly points to the magnetic north of your map, then your map is correctly oriented.

.weather lore

An infallible weather forecast, if a change of weather is coming up, is in the nautical couplet:

"When the rain is before the wind, your topsail halyards better mind,
But when the wind is before the rain, then hoist your topsails up again."

In plain words this says that when rain comes first without wind then expect a long period of bad weather with high winds and heavy rain. But when wind comes first and is followed immediately by rain, then fine weather will follow at short notice.

Many people are trapped by bad weather in the bush every year, and if they but knew of this simple weather sign they could be prepared, and get out to a position of safety before really bad weather sets in.

Another infallible weather signal is the appearance of cumulus nimbus cloud, a foreteller of thunderstorms. While a greenish light in the sky preceding a thunderstorm is an almost certain sign of heavy hail.

.clouds and their reading

Cirrus: This is the "mare's tail" sky of the landsman, shows as long threads or wisps of cloud. This is the highest of all cloud formations, and is a sign of a "high" barometrical pressure, which means fine weather.

Cirro Stratus, and Cirro Cumulus: In these clouds the former is long wispy, cloud, and in the latter rounded small cloud the typical "mackerel" sky. Both are indicators of a high barometric pressure, and fine weather.

Cumulus and Cumulus Nimbus: Cumulus is the high white piled-up masses of cloud seen in summer. When streaked with horizontal bands it is Cumulus Nimbus, or thunder cloud, a sign of coming storms, which may be of short duration, or may indicate a change in the weather generally.

Nimbus: This is the grey ragged cloud which uniformly covers the sky. It is the true rain cloud, and an indication of low barometric pressure and rainy weather.

Storm Scud: This is formless masses of very low cloud driven fast before the wind. It is a sign of very low barometric pressure, and continuing bad weather.