Secrets of Ancient Navigation by Peter Tyson
Oak and triple bronze must have girded the breast of him who first committed his frail bark to the angry sea
--Horace, Odes
"Aye, mate." One can almost hear the weary assent of countless a hoary sailor upon hearing these words of Horace, almost see the rheumy eye staring distantly as if at some ghost ship on the horizon that only he can see. For the old poet's words ring only too true. In the three or four millennia of seafaring before John Harrison came along, how could mariners know where they were going? The sea is literally without landmarks to guide by, a vast, featureless emptiness ready and more than willing to swallow up the lost and unlucky, leaving no trace save the awful memories of those who survived them.

The first seafarers kept in sight of land; that was the first trick of navigation. Follow the coast. To find an old fishing ground or the way through a shoal, one could line up landmarks, such as a near rock against a distant point on land; doing that in two directions at once gave a more or less precise geometric location on the surface of the sea. Sounding using a lead and line also helped. "When you get 11 fathoms and ooze on the lead, you are a day's journey out from Alexandria," wrote Herodotus in the fourth century B.C. The Greeks even learned to navigate from one island to the next in their archipelago, a Greek word meaning "pre�minent sea." They may have followed clouds (which form over land) or odors (which can carry far out to sea).

But what if land were nowhere nearby? The Phoenicians looked to the heavens. The sun moving across the commonly cloudless Mediterranean sky gave them their direction and quarter. The quarters we know today as east and west the Phoenicians knew as Asu (sunrise) and Ereb (sunset), labels that live today in the names Asia and Europe. At night, they steered by the stars. At any one time in the year at any one point on the globe, the sun and stars are found above the horizon at certain fixed "heights" -- a distance that mariners can measure with as simple an instrument as one's fingers, laid horizontally atop one another and held at arm's length. The philosopher Thales of Miletos, as the Alexandrian poet Kallimachos recorded, taught Ionian sailors to navigate by the Little Bear constellation fully 600 years before the birth of Christ:
Now to Miletos he steered his course
That was the teaching of old Thales
Who in bygone days gauged the stars
Of the Little Bear by which the Phoenicians
Steered across the seas
The Norsemen had to have other navigational means at their disposal, for in summer the stars effectively do not appear for months on end in the high latitudes. One method they relied on was watching the behavior of birds. A sailor wondering which way land lay could do worse than spying an auk flying past. If the beak of this seabird is full, sea dogs know, it's heading towards its rookery; if empty, it's heading out to sea to fill that beak. One of the first Norwegian sailors to hazard the voyage to Iceland was a man known as Raven-Floki for his habit of keeping ravens aboard his vessel. When he thought he was nearing land, Raven-Floki released the ravens, which he had deliberately starved. Often as not, they flew "as the crow flies" directly toward land, which Raven-Floki would reach simply by following their lead.

Heeding the flightpaths of birds was just one of numerous haven-finding methods employed by the Polynesians, whose navigational feats arguably have never been surpassed. The Polynesians traveled over thousands of miles of trackless ocean to people remote islands throughout the southern Pacific. Modern navigators still scratch their heads in amazement at their accomplishment. Like Eskimos study the snow, the Polynesians watched the waves, whose direction and type relinquished useful navigational secrets. They followed the faint gleam cast on the horizon by tiny islets still out of sight below the