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Image of a ship's chronometer housed in its wooden box

Ship's chronometer, circa 1907. South Australian Maritime Museum collection.

By 1836 the major problems for mariners finding their way across the oceans had been solved.

There had been great developments in exploring the earth and producing charts to guide shipping. Dutch seafarers had sailed from Europe south past Africa’s Cape of Good Hope and east through the Indian Ocean.  Since 1606 they had encountered the Australian continent and by 1663 had published charts of the Western Australian coast. Britain’s James Cook charted the east coast in 1770. The big step for South Australia came in 1802 when a French expedition led by Nicolas Baudin and a British expedition led by Matthew Flinders charted the southern coast. By 1811, the first complete map of the Australian continent was published in Paris.

The great puzzle that faced navigators in the eighteenth century had been how to measure their longitude, to find how far they had sailed east or west. That problem was solved in the 1770s when John Harrison produced a chronometer, or clock, that was able to keep accurate time at sea. It meant that mariners could carry Greenwich (London) time on long voyages. They could measure their local time at noon when the sun rose to its zenith. They could use the time difference to determine how far they had sailed from Greenwich.

Magnetic compasses had been used in the Mediterranean Sea since at least the twelfth century. The compass needle points to the earth’s magnetic poles. In the early nineteenth century problems with compasses were emerging as increasing amounts of iron were used as fittings on ships. The iron could attract the compass needle, making it deviate from pointing north. Matthew Flinders (1774-1814) pioneered studies of the deviation caused by iron and found that much of it could be corrected by placing a vertical iron bar under the compass.

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