| Map Reading |
| True, Magnetic and Grid North Definition of North There are three types of North: 1) True North 2) Grid North � Grid North is the northern direction of the north-south grid lines on the map. The grid lines on a map provided the most useful and normal reference for measuring bearing on a map; such bearings measured from the Grid North are called grid bearings. These are the grid bearings most commonly used in map reading. 3) Magnetic North � Magnetic North is the direction in which a compass needle points when free from error or disturbance. This needle is to the magnetic pole, which differs from the North Pole; its position varies slightly form year to year. Bearing measured from the magnetic north are called magnetic bearing; these are the bearings read on a magnetic compass, subject to its individual error. Taking a map bearing from a map To read a map bearing from A to B, place the compass with the long side on the line AB and with the line of travel arrow pointing towards B. Then turn the graduated circle and base plate so that the arrow on the base plate points towards grid north and the lines are parallel to the north-south gird lines. The gird bearing of B from A is then read off at the point where the tail of the line of travel arrow cuts the graduation on the circle. Taking a field bearing � Hold the compass horizontally and point the direction of travel arrow at the object � While keeping the compass in this position, turn the graduated circle so that the orienteering arrow on the base plate corresponds with the north (red) end of the needle. � The field bearing is the read off at the direction of travel line. Walking on a bearing � Look straight ahead in the direction of a set bearing. � Pick a landmark at a reasonable distance away. � Hold the compass in front of you as you walk in the direction of the line of travel arrow. � Keep the compass needle and the orienteering arrow coincident. � Take the easiest route to the landmark without looking at the compass. � On reaching the landmark, repeat the sighting procedures and so until you reach you destination |
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| Fig 5.5 Silva Compass set on a map |
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