Stephen Johnston

And as someone who works more readily with visual geometry than with trigonometry and calculation, Alex Boxer's astrolabe has time and again allowed me to quickly check on research questions - so it pops up in my footnotes as well as being a great tool for teaching and public presentation.

Many thanks for this - I had a suspicion that print might beat the online resource, and so it's proved. As I increasingly spend time with medieval sources, I should really get my own paper copy of Cappelli....

I thought it might be - certainly gave me a surprise. (And glad to join so rarified a group of numerical devotees!)

The form of X is stylistically similar to the Merton College astrolabe, even if Latitudo is here in minuscule. This instrument is from the inexhaustible collection of the History of Science Museum in Oxford hsm.ox.ac.uk/collections-... where it has been identified as C13 from Latin Spain.
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Astrolabe plate for latitude 42° from Latin Spain, with three instances of an abbreviation for Roman numeral 40.

Update from a comparably messy astrolabe, which was also extensively reworked but whose plates are mostly original. I've marked up 3 instances of a similar abbreviation for the Roman numeral XL as X', from the bottom upwards: latitude X'II (42°), zenith LX' (90°) and almucantar X'V (45°).
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If you spot anything later that would be very useful - I don't want to overload this one piece of evidence. But it does tie in with the exclusive use of Roman numerals and the provision of plates laid out for the climates, both of which point towards an earlier rather than later dating.

It's also very encouraging because I've gradually been coming round to the idea that the original base layer of this "ugly duckling" astrolabe was much earlier than previously thought. It was reworked c.1400 but this hint of an early Spanish origin is particularly tantalising. More work needed!

Many thanks, Stephen - this is exceptionally helpful, not least because I've now been able to get hold of both your own book and the Lemay article. (And three cheers for the collegial spirit of Bluesky!)

Detail of a latitude plate of a medieval astrolabe at Merton College Oxford, with the inscription CLIMA· III XXX

Though script consistency may not have been the engraver’s strongest suit. Note how the M in CLIMA on the plate for the 3rd climate differs from the previous image, this time no longer in uncial form.
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Detail of a latitude plate of a medieval astrolabe at Merton College Oxford, with the inscription CLIMA· V LATITVDO·XLI.

For context, this is from another plate in the same instrument, where the 5th climate has its latitude (41°) rendered more conventionally as XLI.
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Detail of a latitude plate of a medieval astrolabe at Merton College Oxford, showing the numbering of the almucantar lines in Roman numerals, with an unusual abbreviation for 40.

Paging #medieval #palaeography for an unfamiliar abbreviation of XL on an astrolabe at Merton College Oxford. Does this ring any bells in terms of date or place for @sebfalk.com or @eleonoraandriani.bsky.social? Or anyone else you can think of? (There’s nothing obvious in Cappelli online.)
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Unfortunately, I think most of the candidate suggestions for screw-related t-shirt text will not be printable for a dissertation defence.... 😄

Thanks! Günther posted an announcement to the rete mailing list this afternoon, so I'd already downloaded the free-to-read first 70 pages!

Qibla diagram from chapter 35 of Fifty Chapters for the Ruler on the Science of the Astrolabe (Panjah Bab-i Sultani dar Marifat Usturlab) by Rukn al-Din b. Sharaf al-Din al-Husayni al-Amuli. Qatar National Library, HC.MS.2017.0057, f. 147.

Composed and copied in Herat, this treatise gives an approximate method for the direction to Mecca (the qibla). Herat is in the centre of the figure. The city is north east of Mecca but, since south is at the top of the diagram, Mecca appears here on the diagonal upwards from the centre.
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A display showing three leaves from Fifty Chapters for the Ruler on the Science of the Astrolabe (Panjah Bab-i Sultani dar Marifat Usturlab) by Rukn al-Din b. Sharaf al-Din al-Husayni al-Amuli. Qatar National Library, HC.MS.2017.0057.

One of the two cases features three leaves from a disbound manuscript containing al-Amuli’s treatise on the astrolabe. Originally written for the Timurid prince Baysunghur (d. 1433), this copy is dated 1456 and its text was checked against the author’s autograph version.
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A generous loan from the Qatar National Library has extended the scope of the Lines of Faith exhibition - so it now includes astrolabe manuscripts. It's also extended in time, running until mid-October. Many thanks to the OCIS Librarian Wassilena Sekulova for masterminding the complex logistics!
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Wooden version of a Roman sundial displaying the time in unequal hours. It has been set up for the latitude of Oxford and for the sun's declination (just beyond the solstice), and the shadow of the gnomon falls roughly half way between 1 and 2 on the hour scale.

Good to see that, heatwave or not, my DIY "portable" Roman sundial is still working fine. I simply suspended the dial and turned it so that the shadow of the gnomon was exactly on the hour scale. At 07.20 British Summer Time we were already half way through the second seasonal (unequal) hour.

That should already have been on my homework list! And I can immediately see nice things in it for current work as well as my naive question - though I might need some extra help, eg at n. 224 on the armillary sphere. (Sorry - force of habit - I inadvertently went straight for the instruments....)

Although if I was there (amongst a diverse audience of students of ancient philosophy, medicine and mathematics as well as of Islamic astronomy and alchemy), I know I’d also be asking more general questions about these late Byzantine schools, and particularly their clientele: who was there and why?

Detail from the Johannes Schöner terrestrial globe of 1520, seen in 2023 at the Germanisches Nationalmuseum, Nuremberg.

Sorry! I was getting confused - what I saw in 2023 at the GNM was the Schöner terrestrial of 1520. How could I forget the experience of watching Scotland detach itself from England and purposefully change direction to head off towards the continent?
(Will some of us ever get over Brexit....?)

Updating not hosting!

Thanks very much for hosting - it was still in Nuremberg in 2023 and I'd presumed it hadn't moved. Another reason to visit Stuttgart!

Small equinoctial sundial, closed to show lid with Gothic inscriptions, in the Landesmuseum Württemberg

Ooohh. Never been - looks lovely - and the 1st floor Kunstkammer seems pretty special too. For my current interests, doesn't look like there's many medieval instruments, but then again the online catalogue isn't complete. And I did spot www.landesmuseum-stuttgart.de/sammlung/sam...

Wow. I hadn't even heard of this meeting, so I hope you'll be reporting on it in a fulsome way here on Bluesky (even if you're feeling weary - one last effort before the summer?). Obviously, canonicity gets a thumbs up, but all 4 of the papers straight after yours sound especially up my street too.

Instrument catalogued as "Fake? Astrological Astrolabe" at https://hsm.ox.ac.uk/collections-online#/item/hsm-catalogue-2078

Unlocking one promptly led me to another, again in the Oxford collection – though this is one whose authenticity has been questioned (it's certainly much later than everything else I covered), and definitely in need of more research.
But if you spot any more devices like these, do let me know!
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Manuscript astrological astrolabe by Hanns Herghamer, 1492, at the History of Science Museum, University of Oxford https://hsm.ox.ac.uk/collections-online#/item/hsm-catalogue-9231

Oh yes, I should have remembered that much sooner - but such are the crooked paths of research. It is admittedly on the very rare southern projection, so the Tropic of Cancer rather than Capricorn is at the edge – perhaps that overwhelmed my memory, or maybe I just forgot…..
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Cartoon image of Homer Simpson suffering a “D’oh!” moment.

One wanted to look at paper or parchment astrolabes, rather than just the more familiar metal ones. So I recommended one from Oxford that I recalled from long ago. Only to instantly realise as I saw it on screen that it was another simplified astrological example – FROM MY OWN INSTITUTION!
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Johanna Garzon, Afra Akyol and Maedeh Hosseinzadeh presenting on astrolabes at the Paris Observatoire.

While teaching on the recent Global History of Astronomy training week in Paris (eida.hypotheses.org/seminars-2/t...), I was supporting a group of three students from Iran, Turkey and Argentina/USA who took astrolabes as their project focus.
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And I was right, in a way that is either amusing or embarrassing, depending on one’s point of view. Because the article was already out of date while it was at the printers! Not because someone else had helpfully reported fresh examples, but because I had found “new” ones.
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Handcoloured paper astrological astrolabe pasted onto the inside of the wooden back cover of the “Heidelberger Schicksalsbuch” (Book of Fate), dating from after 1491. Universitätsbibliothek Heidelberg, Cod. Pal. germ. 832 (http://digi.ub.uni-heidelberg.de/diglit/cpg832/0560).

Actually, one of my biggest hopes was simply to flush out more examples of what I’ve christened simplified astrological astrolabes. A key part of the paper was to establish a small initial corpus of these devices in metal, parchment, and printed paper. But surely there are more to be found….
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