posted on Jan, 6 2013 @ 04:28 PM
I think the first true Atlantic mariners were the Phoenicians, when you consider the power and might of all the Eastern Mediterranean cultures -
Egyptians, Greeks, Hittites - theirs was the one culture that was hemmed in by their neighbors and had only one route to expansion - the sea.
Expansion by war and conquering territory of course would have been a more traditional route, but Phoenicians were the remnants of the Canaanite
city-states that never gelled into a true empire that could have dominated it's region in the eastern Med. by such means, instead fighting amongst
themselves more often that their enemies. Perhaps as a consequence they set out to colonize Northern Africa (Carthage was among their great cities),
Hanno explored parts of the African Atlantic coastline, with Phoenicians colonizing the Atlantic coast of both Africa and Spain, potentially trading
with Northern Europeans. The sacking and looting of Carthage and collapse of the Phoenician culture was a true loss, if anyone was poised to be the
first trans-Atlantic navigators, or had the knowledge of such, it were they.
Regarding the 'dioptra' - I know this topic has been covered before here on ATS, but this particular one is surely a ceremonial carving of a dioptra
buried with a famous Egyptian architect, and not an actual functioning dioptra. It was surely a tool used by this architect for land surveying, as
opposed to celestial observation (dioptras can be used for both disciplines). I think that 'context' of where this ornamental piece was found
dictates it was used for land surveying, however - not that it wouldn't also help with establishing cardinal coordinates.
Something else to consider is the role of Sumerian sailors (who plied the ancient Persian Gulf), then Indus and Egyptian navigators who sailed the
northeast monsoon to Africa in the winter and the southwest monsoon in the summers back to the Indian subcontinent. However, this took advantage of
prevailing winds and didn't truly rely on "navigation" - mostly drifting along by luck. It did at least usher in some development in Astronomical
observations to ensure the proper tack. It was a similar feat employed by later Polynesians to sail from Tahiti to Hawaii, by riding prevailing winds
and keeping to the proper tack by navigating by sun and stars.
Most of the tech belonging to ancient mariners might be useful for determining a north-south position (latitude) by sun and stars, but it would not be
able to determine east-west position (longitude) - not until the invention of a reliable marine chronometer in the early 19th c. It's doubtful even
Romans had bothered with true marine navigation, since (as Hanslune pointed out in another thread), they were bound to make landfall in the Med sooner
or later, and basic navigating skills by sun and stars would get them to their destination in a reasonable amount of time. That might suffice in a
body of water like the Med, or the Black Sea, or even the Indian Ocean, but true trans-Atlantic navigation required more precision, charts (at least
of prevailing currents and winds), and a culture supporting such crossings, and the two that best fit that criteria are the Phoenicians and later
Norse navigators (let's not forget Norse sailors reached deep into Russia following waterways and coastlines, as well as all the North Sea isles).
I sense that you are looking for clues about whether ancients mariners may have grasped the nature of the globe, and truly understood the concept of
how to navigate it - they certainly left tantalizing clues along those lines - for instance, the Sumerian 'beru' is a measure of time identical to
our modern hour - and is used in navigation to represent the measure of how long the sun takes to travel across an angular measure of 15 degrees of
the globe - i.e., one longitude. Is there a deeper reason Sumerians chose to divide the day/night cycle into 12 equal increments each? Did they grasp
that a circle (360º), when divided by 15º, would leave 24 equal segments that was equivalent to a length of time needed for the sun to traverse our
globe in one hour? One wonders is only the Sumerians had achieved a working, reliable, marine chronometer, would they have been able to develop true
navigation and chart-making skills? (ps: the Piris Reis map is a good example of what happens when you chart a coast line without using
accurate longitude/latitude measurements - it's didactic but still grossly inaccurate). I should point out that what we have as examples of Sumerian
map making show no concept of latitude or longitudes, instead they drew their maps in a radial representation with a city (and the viewer) placed in
the center, and features (mountains, rivers, cities, etc.) shown radially with distances by how far it would walk to them (using 'beru' as the
standard measure of time, representing both hours or days). Such maps become useless once taken from their origin point - like a classic "you are
here" map in a mall.