A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Peter Fogg
Date: 2009 Jun 20, 06:20 +1000
So, this "great power" (which conquered and colonised Greece and its colonies, more or less for starters) was well and truly founded on a base laid by Eratosthenes and others in the past.
Its fairly typical that the Greeks had the good idea of using the sun's shadow to calculate the circumference of the earth, although to be fair many of their scientific and other ideas were imported from the east following the colonisation of those lands by Alexander the Great.
Most knowledge tends to be derivative We are all standing of the shoulders of others. Such is our strength - that of sharing ideas and systems.
Not to be nit-picky but Eratosthenes was Greek, not Roman. More importantly, he lived well before Rome was the great power it was to become 200 years later.
From "The Word Origin Calendar", Friday, June 19, 2009
In Roman time-reckoning, developed in a sunny and temperate land, the middle of the day occurred at around what we call 3:00 p.m., roughly nine hours after sunrise. This hour was called nonus, meaning "the ninth hour" and referring to the middle of the afternoon. In our system of reckoning, "noon" now stands at the middle of the twenty-four hour day.
Interesting. This would suggest that the Romans did not equate "midday" with the maximum altitude of the Sun. Eratosthenes famously used the Sun and its shadows at local noon to estimate the circumference of the Earth. The Romans from the 1st century BC on surely knew that. Perhaps their time-keeping using the "nonus" is even older and they decided to stick with it... Are there any list members who know more about this particular element of history?
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