Navigation_prior_to_the_compass History_of_the_compass

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prior introduction of compass, geographical position , direction @ sea determined sighting of landmarks, supplemented observation of position of celestial bodies. on cloudy days, vikings may have used cordierite or other birefringent crystal determine sun s direction , elevation polarization of daylight; astronomical knowledge sufficient let them use information determine proper heading. invention of compass enabled determination of heading when sky overcast or foggy, , when landmarks not in sight. enabled mariners navigate safely far land, increasing sea trade, , contributing age of discovery.








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