Re: VMs: How did Ptolemy know about time zones

[Elmar Vogt <elvogt@xxxxxxxxxxx>]

Dan Gibson/CanBooks wrote:

> I believe that Ptolemy wrote around 130 A.D. By that time Arab merchants 
> (Nabataeans) had over two hundred years experience sailing from India to 
> the Red Sea. Some had sailed to China. Arab merchants (Nabataeans) had 
> also established a thriving colony near Rome itself. These merchants 
> used the stars for navigation. Thus they were in an excellent position 
> to observe events taking place from China to Europe. They would surely 
> notice and discuss how events in the stars took place at different times 
> of the day in different locations.

Still -- how many such events are there? I guess you'd have to rely almost 
completely on lunar eclipses.

> The Arabs used several ways to determine latitude. 

Latitude isn't really the question here. You can determine your latitude by 
the height of the sun in summer or winter. But longitude is a different 
issue, and Ptolemy secifically referred to that!

Cheers,

	Elmar, still curious about that cunning bastard

--
Elmar Vogt / Königswarterstr. 18 / 90762 Fürth / GERMANY
elvogt@xxxxxxxxxxx / www.beamends.de / Tel.: (++49/0)911 - 31 52 58

"It is through the truthful exercising of the best of human qualities -
respect for others, honesty about ourselves, faith in our ideals - that
we come to life in God's eyes." (Bruce Springsteen, "Vote for Change")

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