| Map Reading |
| The two other bridges within the squares are at 761327 and 764324. similarly the inn is at 765327 and the halt is at 760323. Should it be necessary to indicate a position even more accurately, the same method of estimation may be extended another stage by dividing each of the small square again into further tenths and by adding a fourth figure to each d the easting and northings. The fourth figure represent one hundredth of the unit. The reference to the halt in Fig 4.2 could be written as 76073235, but such a reference is only required when a six figure reference is not precise enough to defined the point without any doubt. Important points to remember are: 1) All the easting figures are always given before the northing figures, i.e, the first half of any grid reference is the easting and the second half is the northing. 2) Grid reference figures are always given to the reference lines west and south of the point. The six-figure reference to the halt is thus 760323 and NOT 761324. 5. Direction Describing Direction The point of the compass North, south, east and west are the four cardinal points of the compass. There are in all 32 points of the compass but only 16 of them are normally used in map reading for the description of the direction. These are the four cardinal and the twelve intermediate points shown in Fig 5.1 In Fig 5.1 the letter, N, S, E and W stand for North, south, east and west respectively. In the intermediate points these letter are combined, e.g SE is southeast. Bearings A bearing is an angle, measured clockwise that a line makes with a fixed zero line. The zero line is always the north, unless some other zero line is stated. If one stands at the point P, and says the bearing of A is 40o, it means that the line PA makes an angle of 40o with the North Line, see Fig 5.2(a). If one says that the bearing of a is 10o form a zero line PB, its means that the angle between PA and PB is 10o, ,measured clockwise, see Fig 5.2(b). The essential point to remember is that bearing are always measured clockwise form the zero line, Fig 5.3 emphasizes how the angle of the two bearing is always measured clockwise. Fig 5.3: Bearing Back Bearing A bearing gives the direction of a line from the point of observation P to a point A. A back bearing gives the direction from the point A back to the point of observation P. |
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