Postscript: (March 28th 2012). On a University of Hawaii site that also links to contemporary (1999-2000) makers of replica astrolabes, astrolabes in the Greek-speaking world are attributed to “the early centuries BC”, the first being possibly made by Hipparchus. Hipparchus was not born in Europe, nor in mainland Greece, but in (Thracian) Bithynia in Asia minor, east across the Hellespont from what would later be the site of Byzantium. Hipparchus’ adult life appears to have been spent in Rhodes – at that time a centre of mixed population and cultural influences. A standard biography of Hipparchus.
Way back when – in 2007 – Rich Santa Coloma made some observations about this folio, noting that it has what seems to be a pin-mark, the sort you’d expect to see when circles are made with a pair of compasses.
As he realised, of course, people have been using compasses (circinus as Isidore calls them) since the time of the ancient Greeks in the Mediterranean and certainly as far as China by the 6thC AD. Since Egypt and India seem to have been the leaders of the ancient world in geometry and in mathematics, respectively, we can suppose they had sorted out how to draw concentric circles fairly early too.
That doesn’t make Rich’s observation irrelevant.
His pointing out that f.57v has ‘two centres’ (or three?) does take us forward, because (as I’ve just realised, though others may have done before me), the point allows a neat mesh with thoughts about this folio offered by him in 2007 and in 2010 on ‘Ciphermysteries’.
I can’t link to the Vms mailing list and it is a mailing list, so I’ll keep the quote from Rich’s post brief:
[A post from 2007] relates to the possible use of a compass… You can see the pinprick/compass point mark.. a small hole, with raised vellum fibers around it, such as a sharp point would make:
On the next image, the tick mark is marked with a one pixel red dot, which is at pixel 477,330:
I’ve taken the liberty of brightening the picture a little: if the green is still difficult to see, the original link is in the caption.
The red circles are formed exactly from this tick mark.
The second circle is the most “off”, but … I would say there is a good possiblitly this point was used to draw the circles. They are really extremely close.
But the inked “center” dot is not the center of any of the circles, as shown by the green circle.
(details from original artwork with permission ~ thanks to Rich Santa Coloma)
So effectively, the central part of the diagram on folio 57v contains two, and possibly three, ‘centres’.
So, today (2013), while collecting variant forms for “Arabic” star-names on medieval Islamicate instruments, I turned to this astrolabe dated to 1370 AD and was reminded (as I should have been much earlier) that an astrolabe always has effectively more than one ‘central’ point. As folio 57v appears to have.
(If you follow that link, click on the left-hand thumbnail under the dog, and you’ll get a BIG picture).
No need to applaud here, nor rush to gather information about astrolabes. It was done in 2010, at the very least. See post at Ciphermysteries (see below).
Here’s the Ciphermysteries post! (again)
I’m happy too.
I collected another couple of variations for these terms, and a fine example of ‘dog and dragon’ pairing. So good all around. 🙂