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a compass, which may be made in France but used in British Columbia. Conversion of compass readings.—The amount and direction of declination is nearly always shown on better maps. To obtain a true map reading where there is an east declination, add the amount of the declination to
Fig. 9. Relation of magnetic north to true north (simplified). the compass reading; in localities having west declination, subtract the amount. In the field it is usually simplest to use magnetic bearings throughout, since no conversion is then necessary. If the magnetic declination is not known, it can be determined as accurately as the compass will read by taking a bearing on Polaris, the North Star. |
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