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What puzzles me, however, is how they would get
even a rough figure of right-ascension, in the absence of a timekeeper with
any precision. How
accurate could a water-clock be?

That's a great question. This whole thing is very interesting. For myself it
is stimulating, for I finally have the time and interest to delve into and
learn about this stuff.

I've found a bit more in "Astronomy before the telescope", ed. Walker, 1996.
This refers (page 237)
to "... instruments made by the best Asian astronomers, notably Ulugh Beg
(1394-1449) in Samarqand,
whose accuracy was between 5' and 10' of arc". That seems a far cry from the
accuracy Doug quotes,
of "a few seconds" of arc.

That few seconds of arc statement made by the writers of the book is what
got me interested in this story in the 1st place. That kind of accuracy from
the 1400's, if it is true and not an error on their behalf; is really
something else.

And yes, the Muslim world did keep alive and advance science through the
western civilization's long sleep after the fall of the Roman Empire.
Something the entire world should be grateful for.

Thanks for all your inputs. Keep them coming.

   

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