Currents may be invisible to the untrained, but not to seasoned mariners. Photo credit: © Clicks/iStockphoto.com
One of these was currents. From time immemorial, journeys have been made or broken by these undersea winds. The western-trending currents of the Indian Ocean, for one, are likely responsible for the Indonesian-based race of Madagascar, an African island more than 3,500 miles from the nearest bit of Indonesia. Similarly, the clockwise currents in the North Atlantic helped doom one of the greatest land scams in history: Erik the Red's colonization scheme for the island he cleverly dubbed "Greenland." Of the 25 ships that sailed west from Norway in the year 990, only 14 arrived.
The father of those North Atlantic currents—the Gulf Stream—was named by none other than Benjamin Franklin. While deputy Postmaster-General of Great Britain in the 18th century, Franklin noticed that his mail ships to the American colonies took longer than whaling ships. Questioning whalers, he learned of a powerful current originating from the Gulf of Mexico—hence his name for it—and sweeping northeast into the North Atlantic (and, incidentally, giving the British Isles a climate positively balmy for such a northern latitude).
Like currents, trade winds have always been important to mariners. Those blowing heads on yellowed old maps were not mere decoration. In the Indian Ocean, for example, Indian traders over the ages have ridden the northeast monsoon to Africa in the cool, dry winter and taken the southwest monsoon back to the subcontinent in the hot, wet summer. To make their annual voyages from Tahiti to Hawaii, a journey of several thousand miles, the Polynesians hitched a ride on the prevailing south-easterly wind, setting a starboard tack and sailing northeast.
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