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Stephen Johnston @stephenaj.bsky.social · 17/08/2026

Occasionally (very occasionally) I emerge from medieval astrolabe obsession. Here's a piece from last year, now released from publisher embargo. Inspired by a museum acquisition and C19 in focus: "Object lessons from the asylum: the portable museum of Thomas E. Dexter" ora.ox.ac.uk/objects/uuid...

ora.ox.ac.uk

Object lessons from the asylum: the portable museum of Thomas E. Dexter - ORA - Oxford University Research Archive

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Stephen Johnston @stephenaj.bsky.social · 12/08/2026

Mais il y a du monde sur la montagne - a real occasion for family outings

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Stephen Johnston @stephenaj.bsky.social · 12/08/2026

Incredible weather in Ghent! In the Pyrénées it's glimpses between the clouds

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DLR-next @dlr-next.bsky.social · 10/08/2026

Weil es so kompliziert ist, hier nochmal eine unserer aufwendigen Visualisierungen, die (natürlich nur stark vereinfacht) den Unterschied zwischen einer partiellen und einer totalen Sonnenfinsternis zeigt.

Mal wieder eines unserer Spaßbilder, das wir hier aus dem Archiv gekramt haben. Wobei es eigentlich zwei Bilder sind, und zwar jeweils mit zwei runden Keksen auf einer Tischplatte. Im linken Bild liegt ein Schokokeks nur teilweise auf einem hellen Keks, sodass davon ein Großteil unbedeckt bleibt. Im rechten Bild liegt der Schokokeks ganz auf dem hellen Keks - na ja, jedenfalls fast.

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Stephen Johnston @stephenaj.bsky.social · 25/07/2026

Anyone up for reading a #medieval symbol (or two)? Here's the rete of an astrolabe at HSM Oxford (hsm.ox.ac.uk/collections-...) - with the circle of zodiac signs for the sun's place in the ecliptic and a selection of star pointers. It's been variously dated to c. 1360 and c. 1400. 1/4

Brass rete of a medieval astrolabe: metal disc cut out to leave a circle for the ecliptic with the names of the zodiac signs and a framework of arcs supporting named star pointers.

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Stephen Johnston @stephenaj.bsky.social · 12/07/2026

If everything goes according to plan, there will be an article in the December issue of the Bulletin of the Scientific Instrument Society. As you'll see, the qualified "newness" of the find isn't just because it's an old object. It was described 70 years ago when sold at a London auction. 1/2

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Stephen Johnston @stephenaj.bsky.social · 12/07/2026

Just published online: a blog post with the first findings from my January research trip to Jacksonville, Florida. This is the unexpected location of a remarkable "new" astronomical compendium by the 16th-century London maker Humfrey Cole. More to follow.... scientificinstrumentsociety.org/blog/

A cotton-gloved hand holds a silver circular disc, itself part of a larger astronomical compendium. The volvelle disc carries an engraved zodiac-calendar scale and two independently rotating discs, one with a sun pointer underneath a smaller disc with a moon pointer. The centre of the moon disc has an astrological aspectarium and a window to show the phase of the moon. Beyond a hinge, a part of another circular face of the instrument is visible.

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Stephen Johnston @stephenaj.bsky.social · 30/06/2026

For all those dropping everything to attend this seminar tomorrow, there's now a new, simplified link from @luiscamposribeiro.bsky.social: us02web.zoom.us/j/82936830101 See you there!

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Stephen Johnston @stephenaj.bsky.social · 26/06/2026

At the time of his death in 2023, Jim Bennett had begun a study of Elizabethan navigation. Only its introduction was approaching completion; the edited draft has now been published in the online journal of the @hakluytsociety.bsky.social. Direct download from www.hakluyt.com/downloadable...

hakluyt.com

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Stephen Johnston @stephenaj.bsky.social · 25/06/2026

Another edition of the excellent Coffee with a Codex series - this time playing away from home with a new acquisition in upstate New York (www.rit.edu/carycollecti...). The live timing was perfect for a viewing party at GHA 2026 eida.hypotheses.org/seminars-2/2....

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Stephen Johnston @stephenaj.bsky.social · 07/06/2026

Being back in Paris meant another chance to visit the Réserves of the @museeartsetmetiers.bsky.social in St Denis. This time I was able to take a microscope to document this astrolabe - thought to be (at least partly) from the workshop of Regiomontanus.

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Stephen Johnston @stephenaj.bsky.social · 07/06/2026

👀 "This project has received $0 in research funding"👀 A great reminder that funding does not automatically equate to research excellence!

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Stephen Johnston @stephenaj.bsky.social · 07/06/2026

On Monday I get to present with some of the small but incredible collection of @labnf.bsky.social. It's extremely cool to begin a hands-on session by saying "This 11th-century celestial globe is one of the two oldest surviving Islamicate examples in the world." gallica.bnf.fr/ark:/12148/b...

Detailed view of part of a brass celestial globe showing constellations, stars and the graduated arcs of the ecliptic and equator, with a horizon and meridian ring.

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Stephen Johnston @stephenaj.bsky.social · 06/06/2026

Looking forward to welcoming the new cohort of international students in Paris on Monday. And also very conscious of all the hard work behind the scenes to run this marvellous approach to the astral sciences again, this time with a new focus. Hats off to the core team for their organising efforts!

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Stephen Johnston @stephenaj.bsky.social · 04/06/2026

On this day in 1583.... (makes a great change from following the news in 2026)

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Stephen Johnston @stephenaj.bsky.social · 15/05/2026

Astrolabes, astrological rolls and maps, among other goodies, all available online next Monday and Tuesday

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Stephen Johnston @stephenaj.bsky.social · 08/05/2026

Remarkable drawing by Frances Yates from 1952, as she was studying Giordano Bruno's art of memory. This is the lead image for Relics, a new student-curated exhibition at the @warburginstitute.bsky.social. Much looking forward to seeing this up close.... mailchi.mp/sas/news-fro....

Circular diagram on paper with fold marks. The outer rings of the circle are lettered in black ink and the inner in red.

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COSMOPOET @cosmopoet.bsky.social · 18/04/2026

This week dedicated to #diagrams is now over, but the work continues towards the publication of our results and the next phase in the life of the #EIDA community. Huge thanks to @obs-paris-psl.bsky.social for hosting us and for sharing it's beautiful secrets with us! #msca #histsci

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Stephen Johnston @stephenaj.bsky.social · 15/03/2026

Random, and with a dash of mystery - not even some prosaic alt-text to dispel the intrigue of the final image......

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Stephen Johnston @stephenaj.bsky.social · 15/03/2026

Is that first one the dials of Gonville and Caius College? Or am I overanticipating my own visit there on Tuesday?

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Stephen Johnston @stephenaj.bsky.social · 21/02/2026

Astrology and the writing of history, addressed in a chunky 512 pages, and with an intriguing cover image too (a celestial planisphere from some sort of architectural setting? Will have to get the book to find out....)

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Stephen Johnston @stephenaj.bsky.social · 16/02/2026

... and diagrams that were assembled and bound separately from a written text that they must have accompanied. But did Rossetti publish such an astronomical work? Not sure. (But his fortification book has images that remind me of fractals and the en.wikipedia.org/wiki/Mandelb... !)

Fortification diagram from Donato Rossetti, Fortificazione a rovescio (Turin 1678), from https://babel.hathitrust.org/cgi/pt?id=gri.ark:/13960/t6rz6j63z&seq=5&view=1up

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Stephen Johnston @stephenaj.bsky.social · 16/02/2026

Call for papers as part of the Scientific Instrument Commission meeting in Neuchâtel on 7-11 September 2026: “Mathematical Instruments and Medieval Libraries: Manuscript Practices and Material Circulation”. Deadline 25 February and full details at hcommons.org/members/saje...

hcommons.org

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Centre for the Study of Manuscript Cultures (CSMC) @csmc-hamburg.bsky.social · 15/01/2026

Unfolding the multiple lives of a shipbuilding manuscript: Our first Artefact of the Month in 2026 is known as 'Fragments of Ancient English Shipwrighty' and reveals the interactions between mathematics and practice in the Scientific Revolution: uhh.de/csmc-aom-35

The first page of Fragments of Ancient English Shipwrighty, showing Baker’s secretary hand and the unfinished drawings of Noah’s Ark and of shipbuilders. Reproduced by permission of the Pepys Library, Cambridge.

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Stephen Johnston @stephenaj.bsky.social · 08/01/2026

First ever visit to the National Art Library www.vam.ac.uk/info/nationa... at the V&A Museum. Cheapskate tip: register in advance, pick up your reader card and only then go to the cloakroom to hand in your bag - now for free.

View of the first reading room of the National Art Library, London with desks and a gallery of books; image from https://www.vam.ac.uk/info/national-art-library

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Stephen Johnston @stephenaj.bsky.social · 08/01/2026

Timeline cleanse: #OTD 2016 at the British Library to view these extraordinary objects (other reader for scale). I first saw them in 1997 in the old BL MSS Room and finally published '"Preciseness and Pleasure": The Astrological Diptychs of Thomas Hood' in 2018 in doi.org/10.1163/9789...

Two pairs of large parchment diptychs on a reading room desk.

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Stephen Johnston @stephenaj.bsky.social · 06/01/2026

The annotated husband and wife Rantzau tract! ❤️

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Stephen Johnston @stephenaj.bsky.social · 06/01/2026

I loved the image at first sight but couldn't immediately fathom how it was created. Now there is a wonderfully clear thread to explain the kit and process, with the bonus of a hi-res zoomable version at the end. Hmm, could I print out a large version to go on the wall? (Or a backlit transparency?!)

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Cees Bassa @cbassa.bsky.social · 01/01/2026

Happy new year! My all sky camera imaged the sky every 15 seconds and this picture shows what happened in the sky in 2025. It shows the length of the night and day with the hourglass shape, the monthly lunar cycle with the diagonal bands, the elevation of the Sun at local noon, and lots of clouds.

The image shows the hourglass shape of the length of the day and night over the 365 days in 2025. Diagonal bands indicate when the Moon was up in the night sky.

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Mohamed Qassiti @mqassiti.bsky.social · 05/01/2026

Just shared by Samuel Gessner @sgessner.bsky.social via the Rete mailing list: The great programme of the international conference “Beyond Books: Instruments and Knowledge in #Libraries”, 14–15 January 2026 at @mhngeneve.bsky.social. #histstm #histsci #medievalsky @stephenaj.bsky.social

Programme of the international conference “Beyond Books: Instruments and Knowledge in Libraries”, 14–15 January 2026 at the Musée d’histoire des sciences, Geneva.

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Commission for the History of Ancient and Medieval Astronomy @chama-dhst.bsky.social · 17/12/2025

The call for the 2026 Training Week: Global History of Astronomy on Primary Sources – A Focus on Cosmology, Physics and Astrology is now open! eida.hypotheses.org/seminars-2/2... June 8-12 2026 Bibliothèque nationale de France, Observatoire de Paris Deadline: 30/01/26 #historyofastralsciences

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Stephen Johnston @stephenaj.bsky.social · 02/12/2025

As the other external committee member with @eleonoraandriani.bsky.social I'm also hugely looking forward to the results of this doctoral project over the next few years - it will be genuinely fascinating to see the Escorial manuscript deeply investigated and fully unveiled.

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Stephen Johnston @stephenaj.bsky.social · 13/11/2025

Strictly local #Oxford interest, but can't help blurting out #Bodleian news. After at least 40 years of using the central library, and restricted to reading onsite, I've just collected a couple of books which I am about to walk out the door with. A loan, but feels like I'll be apprehended for theft!

Front cover of hardback book on 15th-century Viennese astronomer/astrologer Johannes von Gmunden (ed. Simek/Klein, 2012).

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Guy Sechrist, PhD @guysechrist.bsky.social · 08/11/2025

Very excited to see the proofs of my newest (newest) article for this December’s issue of the Bulletin of the Scientific Instrument Society.

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Stephen Johnston @stephenaj.bsky.social · 07/11/2025

Short thread 🧵on the frequently invisible realm of #histsci connections, seen through the medium of #secondhand books – in this case one bought online which arrived in the post today. #Hebrew #medieval #astronomy #tables #Manchester (1/4)

Yellow bookmark from Salsus Books in Kidderminster.

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Tobias Wilson-Bates @phdhurtbrain.bsky.social · 05/11/2025

Impossible to overstate how exciting field conferences are for academics. We spend 11.95 months a year with people only understanding 5-15% of our jokes and references, but then for three glorious days 😍😍😍

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Stephen Johnston @stephenaj.bsky.social · 05/11/2025

And now it's even in the Warburg's newsletter this morning - handily available at mailchi.mp/sas/news-fro... even for whose who're not subscribers (through why ever wouldn't you be?). You don't have to scroll down far for "In the Media".

mailchi.mp

Read the latest news from the Warburg Institute

Catch up with all of our latest news and opportunities.

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COSMOPOET @cosmopoet.bsky.social · 14/10/2025

🧵🧵In the very first instalment of this guest author and fellow stargazer 🤩💫and skywalker 🌌👣series, it is my pleasure to introduce Stamatina Mastorakou (@smasto.bsky.social), the October Cosmopoet! Here's what she had to share about her chosen poem:

isaw.nyu.edu

Byzantine Silver Plate Depicting Aratus and Urania

This Byzantine silver plate is on view at the Institute as part of the exhibition "Time and Cosmos in Greco-Roman Antiquity".

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Stephen Johnston @stephenaj.bsky.social · 14/10/2025

Decided that jaunty isn't quite the right word in such cases. More like determinedly oblique? (Prompted by stumbling on this example of an astrologer from 1675, in a series of prints under the wonderful title Le Ventiquattr'Hore dell'humana felicità www.ashmolean.org/collections-...)

Detail from a 1675 etching with the figure of an astrologer holding a book and reaching towards an armillary sphere with a pair of dividers. The pedestal on which the sphere sits has a sheet of diagrams and a horoscope on an unrolled scroll.

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Stephen Johnston @stephenaj.bsky.social · 05/10/2025

My final piece of hand engraving on copper, at the end of an excellent two-day course (online!). Various slips and scratches (some disguised by the blurry image) but the main point was to make me see better when I'm examining historical mathematical instruments. So much more to look out for now.

Small copper plate hand-engraved with a symmetrical decorative pattern. The visible metal surface is about 6cm square.

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Stephen Johnston @stephenaj.bsky.social · 25/09/2025

Rolling out the red carpet for Saturday's #astrolabe study day in #Oxford, here with Taha Yasin Arslan - freshly arrived from Istanbul Medeniyet University - to set up our metalworking stations. Files, fret saws, rivets and hammers at the ready!

Dr Taha Yasin Arslan standing in a hall on a red carpet surrounded by three tables with astrolabe parts, clamps and tools.

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Stephen Johnston @stephenaj.bsky.social · 19/09/2025

Deciding I might as well embrace my new status as “unfunded hobbyist researcher” (sorry: UK-only in-joke), so here's my new kit just arrived from the Hand Engravers’ Association. (I had to supply my hand measurement so that the burin/graver could be made to the right size.)

Set of tools and materials for hand engraving laid out on an oil cloth

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Stephen Johnston @stephenaj.bsky.social · 16/09/2025

Ever wondered what Chaucer’s clerk Nicholas would get up to with his astrolabe in the Miller’s Tale? In 10 days there’s a chance to learn about and make this most iconic #medieval instrument at a study day at the #Oxford Centre for Islamic Studies. Literally #MedievalSky!

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Stephen Johnston @stephenaj.bsky.social · 14/09/2025

Just two weeks to go until the #Oxford #astrolabe study day on Saturday 27 September! Learn the making and use of this most iconic scientific instrument – with the bonus that everyone attending gets to assemble and take home their own modern laser-cut astrolabe.

A prototype version of a modern astrolabe designed and produced by Kevin Karney, pinned together with cocktail sticks and held up by string.

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Stephen Johnston @stephenaj.bsky.social · 24/08/2025

It also made me look again at the Shah Abbas astrolabe in Oxford, from the first year of his rule, and therefore shortly before this astrologically overdetermined event.

Detail of the rete of an astrolabe by Muhammad Amin ibn Amirza Khan an-Nakha`i for Shah Abbas, 1588: https://hsm.ox.ac.uk/collections-online#/item/hsm-catalogue-2107

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Stephen Johnston @stephenaj.bsky.social · 15/08/2025

Very pleased to see them safely back on display, though it's been wonderful to have the chance to study them closely while the library refurbishment was underway - thanks so much for the opportunity!

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Stephen Johnston @stephenaj.bsky.social · 07/07/2025

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.) 1/3

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.

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Stephen Johnston @stephenaj.bsky.social · 02/07/2025

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! 1/3

Two showcases with manuscripts from the Qatar National Library, with an animated astrolabe projection between them.

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