“When you get 11 fathoms and ooze on the lead, you are a day’s journey out from Alexandria.”
Herodotus, 4th Century BCE
I often think of the Greek historian, Herodotus more as a narrator of life than a pedantic historian. A prolific writer, he travelled the world drawing on the ancient Ionian tradition of storytelling. He gleaned the tales and legends from oral poetry, sung by wandering minstrels he met on his journeys. Yet, he was meticulous, even systematic in testing the accuracy of the information before orchestrating all of the scattered facts into a well-constructed and dynamic account.
Herodotus, with all of his wanderings, knew the rules of navigation. Follow the coast; and keep a look-out for landmarks along the shoreline. A precise geometric location on the ocean could be ascertained by lining up landmarks, say a nearby boulder against a distance point of land, from two different directions. Taking a sounding, which used poles or a weighted sounding line when measuring greater depths, would add a measure of comfort.
The Greeks mariners were creative, navigating from one island to the next in their archipelago. They followed the cloud formations, recognizing they generally form over land masses. They used their noses to detect “land” odors that were known to drift far out into the waters.
The Greek’s greatest advantage came in the form of Thales of Miletos, recognized as the first true mathematician. He used geometry to determine the distance of ships from the shore. According to the Alexandrian poet Kallimachos, Thales of Miletos taught Ionian sailors to navigate by the Little Bear or the Ursa Minor constellation in the northern sky. Even so, the Greeks were not the first to follow the stars.
“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.”