 Printer
Friendly Copy  Download
This Document
Direction Finding
Direction finding is an important but
often overlooked skill, both in real life and scouting life. The
ability to know where you are and where you are going can be
potentially lifesaving. This section aims to address part of the
'where you are going' problem. If you want to find related material
then check out the Map and Compass sections of Scouting.
There are many methods of direction finding, perhaps the most
commonly known being the magnetic compass. However, there are
methods that are easier and quicker than this (for rough direction
finding) and methods that do not rely upon you having any special
materials at all (other than the use of your eyesight).
|
Shadow Stick Methods
The Earth's revolution on its axis produces the changes from
light to darkness and its orbit around the sun produces the
seasons (Note: NOT because of the distance to the sun. In
actual fact, the earth is closest to the sun during the
winter months). The earth is tilted at an angle to the sun
and first the north and then the south becomes nearer to it,
the closest point traversing from the Tropic of Cancer (23.5°
N) to the Tropic of Capricorn (23.5° S), the sun being
above Cancer on 22 June and above Capricorn on 22 December.
It is above the Equator on 21 March and 21 September.
The sun rises in the east and sets in the west - but not
EXACTLY in the east and west. Indeed there is a seasonal
variation. In the Northern Hemisphere, when at its highest
point in the sky, the sun will be due south; in the Southern
Hemisphere this noonday point will mark due north. The
hemisphere will be indicated by the way that shadows move;
clockwise in the north, anticlockwise in the south. Shadows
can be a guide to both direction and time of day.
|
Method 1
On a patch of flat, clear ground place a metre-long
(3ft) stick as upright as possible. Note where ites
shadow falls and mark the tip with a pebble or stick
(a). Wait at least 15 minutes and mark the new
shadow tip (b). Join the two and you have the
directions of east and west. The first mark is west.
North-South will be at right angles to this line.
This method works at any time of the day when there
is sunshine and at any latitude. |
|
|
|
Method 2
Another, more accurate, method (if you have the
time) is to mark the first shadow tip in the
morning. Draw a clean arc at exactly this distance
from the stick, using the stick as a centre point.
As midday approaches the shadow will shrink and
move. In the afternoon, as the shadow lengthens
again, mark the EXACT spot where it touches the arc.
Join the two points to give east and west. West is
the morning mark.
|
|
Direction by Watch
A traditional watch with two hands can be used to find direction,
provided it is set to true local time (without variation for summer
daylight saving and ignoring conventional time zones which do not
match real time). The nearer the Equator you are the less accurate
this method will be, for with the sun almost directly overhead it is
very difficult to determine its direction.
|
Northern Hemisphere
Hold the watch horizontal. Point the hour hand at the sun.
Bisect the angle between the hour hand and the 12 mark to give
a north-south line.
|
|
|
Southern Hemisphere
Hold the watch horizontal. Point 12 towards the sun. A
mid-point between 12 and the hour hand will give you the
north-south line
|
|
Improvised and Natural Pointers
|
Improvised Compasses
A piece of ferrous metal wire (a sewing needle is ideal)
stroked repeatedly in one direction against silk
will become magnetized and can be suspended so that it
points north. The magnetism will not be strong and will
need regular topping up.
Suspend the needle in a loop of thread, so that it does
not affect the balance. Any kinks in or twisting of the
thread must be avoided.
|
|
Stroking with a magnet, should you have one, will be
much more efficient than using silk. Stroke the metal smoothly
from one end to the other in one direction only.
A suspended needle will be easier to handle on the move but in
camp or when making a halt a better method is to lay the needle on
a piece of paper, bark or grass and float it on the surface of
water.
|
|
Using Electricity
If you have a power source of two volts or more (a small
dry battery, for instance) the current can be used to
magnetize the metal. You will also need a short length of
wire, preferably insulated. Coil the insulated wire around
the 'needle':If it has no ready-made insulation wrap a few
layers of paper or a piece of cardboard around the needle
first. Attach the ends of the wire to the terminals of the
battery for five minutes.
|
Razor Blade Compass
A thin flat razor blade can also be used as a compass needle
because it is made of two metals bonded together. It can be
magnetized simply by stropping WITH CARE against the palm of the
hand. Suspend it.
|
North Pole Plant which grows in South Africa, leans
towards the north to gain full advantage of the sun.
|
Compass Plant of North America directs its leaves
in a north-south alignment. Its profile from east or west
is quite different from that of north or south.
|
Plant Pointers
Even without a compass or the sun to give direction you can get an
indication of north adn south from plants. They tend to grow
towards the sun so their flowers and most abundant growth will be
to the south in the Northern Hemisphere, the north in the South.
On tree trunks moss will tend to be greener and more profuse on
that side too (on the other side it will be yellowish to brown).
Trees with a grainy bark will also display a tighter grain on the
north side of the tree trunk.
If trees have been felled or struck down the pattern of the rings
on the stump also indicates direction - more growth is made on the
side towards the Equator so there the rings are more widely
spaced. There are even species of plant known for their
north-south orientation.
Wind Direction
If the wind direction of the prevailing wind is known it can be
used for maintaining direction - there are consistent patterns
throughout the world but they are not always the same the whole
year round.
Where a strong wind always comes from the same direction plants
and trees may be bent in one direction, clear evidence of the
wind's orientation. But plants are not the only indication of wind
direction: birds and insects will usually build their nests in the
lee of any cover and spiders cannot spin their webs in the wind.
Snow and sand dunes are also blown into distinctive patterns by a
prevailing wind which blows from the outside of the high central
ridges.
Astronomical Direction Finding
The Moon
The moon has no light of its own, it reflects that of
the sun. As it orbits the earth over 28 days the shape of the
light reflected varies according to its position. When the moon is
on the same side of the earth as the sun no light is visible -
this is the 'new moon' (a) - then it reflects light froms its
apparent right-hand side, from a dradually increasing area as it
'waxes'. At the full moon is it on the opposite side of the earth
from the sun (b) and then it 'wanes', the reflecting area
gradually reducing to a narrow sliver on the apparent left-hand
side. This can be used to identify direction.If the moon rises
BEFORE the sun has set the illuminated side will be on the west.
If the moon rises AFTER midnight the illuminated side
will be in the east. This may seem a little obvious, but i does
mean you have the moon as a rough east-west reference during the
night.
Direction by the Stars
|
The Northern SkyThe
main constellations to learn are the Plough, also known as
the Big Dipper (a), Cassiopeia (b) and Orion (c), all of
which, like all stars in the northern sky, apparently circle
the pole star (d), but the first two are recognizable groups
that do not set.
These constellations come up at different times
according to latitude and Orion is most useful if you are
near the Equator.
Each can be used in some way to check the
position of the pole star, but once you have learned to
recognize it you probably will not need to check each time.
|
|
A line can be drawn connecting Cassiopeia and the
Plough throught the Pole Star. You will notice that the two lowest
stars of the Great Bear (as shown here) point almost to the Pole
Star. It will help you to find these constellations if you look
along the Milky Way, which stretches right across the sky, appearing
as a hazy band of millions of stars.
The Plough (Big Dipper)
The plough is the central feature of a very large constellation, the
Great Bear (Ursa Major). It wheels around the Pole Star. The two
stars Dubhe (x) and Merak (y) point, beyond Dubhe, almost exactly to
the Pole Star about four times further away than the distance
between them
|
CassiopeiaCassiopeia is
shaped like a W and also wheels around the North Star. It is
on the opposite side of the Pole Star and about the same
apparent distance away as the Plough.
On clear, dark nights this constellation may be
observed overlaying the Milky Way. It is useful to find this
constellation as a guide to the location of the Pole Star,
if the Plough is obscured for some reason. The centre star
points almost directly towards it.
|
|
|
|
OrionOrion rises above
the Equator and can be seen in both hemispheres. It rises on
its side, due east, irrespective of the observer's latitude,
and sets due west. Mintaka (a) is directly above the
Equator. Orion appears further awau from the Pole Star than
the previous constellations. He is easy to spot by the three
stars forming his belt, and the lesser stars forming his
sword.
|
|
Other StarsOther stars
that rise and set can be used to determine direction. Set
two stakes in the ground, one shorter than the other, so
that you can sight along them. Looking along them at any
star - except the Pole Star - it will appear to move. From
the star's apparent movement you can deduce the direction in
which you are facing.
Apparently Rising = facing east
Apparently falling = facing west
Looping flatly to the right = facing south
Looping flatly to the left = facing north
|
These are only approximate directions but you
will find them adequate for navigation. They will be
reversed in the Southern Hemisphere.
|
|
|
Reading the Southern SkyThere
is no star near the South Celestial Pole bright enough to be
easily recognised. Instead a prominent constellation is used
as a signpost to south: the Southern Cross (Crux) a
constellation of five stars which can be distinquished from
two other cross shaped groups by its size - it is smaller -
and its two pointer stars.
|
One way to find the Southern Cross is to look along the
Milky Way, the band of millions of distant stars that can be seen
running across the sky on a clear night. In the middle of it there
is a dark patch where a cloud of dust blocks out the bright star
background, known as the Coal Sack. On one side of it is the
Southern Cross, on the other the two bright pointer stars.
|
Finding SouthTo locate
south project an imaginary line along the cross and four and
a half times longer and then drop it vertically down to the
horizon. Fix, if you can, a prominent landmark on the
horizon - or drive two sticks into the ground to enable you
to remember the position by day.
|
|
Pictures and information courtesy of ScoutingResources.org.uk
|
Scouting
Resources
