Re: VMs: Anthony Askham's zodiacal volvelles and similar Irish volvelles

[Nick Pelling <incoming@xxxxxxxxxxxxxxxxx>]

Hi everyone,

It looks as though Askham merely copied the volvelles, rather than 
originated them: here's a good description of an extremely rare printed 
version from 1551, with the volvelles still intact (unassembled) in the 
print - $7500 seems a good price to me for this, but what do I know? :-p

http://www.reeseco.com/cat216/cat216f.htm

Here's another description, with various-size images of a volvelle designed 
to demonstrate lunar eclipses:

http://www.hps.cam.ac.uk/starry/sacrobooks.html

However, I should perhaps point out that Askham's translation of De Sphaera 
seems to have incorporated other calendrical elements, perhaps from 
Sacrobosco's Compotus (which specifically dealt with calendrical problems) 
or elsewhere: and that the volvelles appear in this section. De Sphaera was 
used as an astronomical textbook for centuries (it was later recommended 
for this by Melanchthon, for example), and there has been considerable 
academic interest in the alterations and extensions made to it by later 
authors - as well as Lynn Thorndike's 1949 book, Owen Gingerich has written 
on this.

So, it may well have been the case that Askham was translating from a 
printed book or incunabulum, which had been extended by a more contemporary 
author.

It should also be pointed out that the idea of adding of volvelles to 
Sacrobosco's De Sphaera (which appeared in numerous incunabulum editions) 
only seems to have occurred circa 1500: if the VMS' volvelles can be proven 
to be derived from this tradition, it would give an earliest date for the 
VMS of circa 1500.

All the same... I have a strong feeling that Askham's volvelles are likely 
to turn out to be more conventional properly-functional volvelles (ie, ones 
that actually do a job), whereas the diagrams in the VMS are merely 
"volvelle-like", or "suggestive of volvelles" - a presentation of 
information, not a rotating informational tool per se. But we shall no 
doubt see...

Cheers, .....Nick Pelling.....


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