Stephen Johnston
@stephenaj.bsky.social
Curator Emeritus at Oxford's History of Science Museum, with interests in instruments and material culture. Current research focus on armillary spheres and astrolabes in medieval Europe. (Disclaimer: focus known to wander.)
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...
Object lessons from the asylum: the portable museum of Thomas E. Dexter - ORA - Oxford University Research Archive
ora.ox.ac.uk
August 17, 2026 at 9:16 AM
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...
Haha - how wrong I was!
August 12, 2026 at 7:17 PM
Haha - how wrong I was!
Mais il y a du monde sur la montagne - a real occasion for family outings
August 12, 2026 at 6:05 PM
Mais il y a du monde sur la montagne - a real occasion for family outings
Incredible weather in Ghent! In the Pyrénées it's glimpses between the clouds
August 12, 2026 at 6:03 PM
Incredible weather in Ghent! In the Pyrénées it's glimpses between the clouds
Reposted by Stephen Johnston
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.
August 10, 2026 at 8:31 AM
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.
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
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
July 25, 2026 at 9:19 AM
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
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
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
1/2
Just finished reading your blog post. Very exciting find! Eager to learn more about this object.
July 12, 2026 at 11:01 AM
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
1/2
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/
scientificinstrumentsociety.org/blog/
July 12, 2026 at 7:01 AM
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/
scientificinstrumentsociety.org/blog/
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!
us02web.zoom.us/j/82936830101
See you there!
I hope you might be interested in my talk on Henry Coley and his astrological notebooks this Wed (1 July) at 6 pm Lisbon time. Zoom link/QR code is in the poster below. #earlymodernsky #astrology #almanacs #historyofscience #manuscripts #helenaavelarseminar
June 30, 2026 at 10:27 AM
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!
us02web.zoom.us/j/82936830101
See you there!
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...
Direct download from www.hakluyt.com/downloadable...
www.hakluyt.com
June 26, 2026 at 5:54 AM
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...
Direct download from www.hakluyt.com/downloadable...
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....
If you missed our visit with Rochester Institute of Technology's Cary Collection 15th century Italian copy of Johannes de Sacrobosco's De Sphera Mundi (bound with two other texts) you can watch it now! It has some unusual diagrams that are worth seeing.
youtu.be/FSyZjp5Fm4g
youtu.be/FSyZjp5Fm4g
Coffee with a Codex: Astronomy Manuscript in Rochester, NY
YouTube video by SchoenbergInstitute
youtu.be
June 25, 2026 at 4:30 PM
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....
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.
This was a first reconnaissance visit. The exceptional instruments will need further study. Among them an astrolabe from the workshop of Regiomontanus, whose replacement horse was wedged in so tightly that we could not open it. 17/25
June 7, 2026 at 8:58 AM
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.
👀 "This project has received $0 in research funding"👀
A great reminder that funding does not automatically equate to research excellence!
A great reminder that funding does not automatically equate to research excellence!
June 7, 2026 at 8:20 AM
👀 "This project has received $0 in research funding"👀
A great reminder that funding does not automatically equate to research excellence!
A great reminder that funding does not automatically equate to research excellence!
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...
gallica.bnf.fr/ark:/12148/b...
June 7, 2026 at 4:18 AM
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...
gallica.bnf.fr/ark:/12148/b...
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!
Starting on Monday we will be teaching the history of the astral sciences on a global scale with the historical sources themselves: manuscripts, prints, globes, astrolabes - thanks to @labnf.bsky.social and @obs-paris-psl.bsky.social for hosting us!! ✨✨ eida.hypotheses.org/seminars-2/2... #histsci
2026-Training week: Global history of astronomy week on primary sources A focus on cosmology, physics and astrology
org.: Eleonora Andriani, Christian Förstel, Victor Gysembergh, Catherine Hofmann, Matthieu Husson, Anuj Misra, Han Qi, Stephen Johnston, Agathe Keller, Romain Lefebvre, Guillaume Loizelet, Divna Manol...
eida.hypotheses.org
June 6, 2026 at 9:40 PM
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!
On this day in 1583....
(makes a great change from following the news in 2026)
(makes a great change from following the news in 2026)
In London, Bartholomew Newsam, clock-keeper to the queen, receives a payment of 32s 8d for 'mending of clocks during the past year.' This clock, belonging to the British Museum, is an example of his work. 5/
June 4, 2026 at 8:58 PM
On this day in 1583....
(makes a great change from following the news in 2026)
(makes a great change from following the news in 2026)
Astrolabes, astrological rolls and maps, among other goodies, all available online next Monday and Tuesday
📣The collaboration between @obs-paris-psl.bsky.social and @csmc-hamburg.bsky.social continues with the second workshop dedicated to the spatio-temporal profile of multigraphic written artefacts: 18–19 May 2026, Paris, at Observatoire de Paris and online. 🤩
May 15, 2026 at 3:50 PM
Astrolabes, astrological rolls and maps, among other goodies, all available online next Monday and Tuesday
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....
mailchi.mp/sas/news-fro....
May 8, 2026 at 4:19 PM
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....
mailchi.mp/sas/news-fro....
Reposted by Stephen Johnston
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
April 18, 2026 at 12:08 PM
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
Random, and with a dash of mystery - not even some prosaic alt-text to dispel the intrigue of the final image......
March 15, 2026 at 3:45 PM
Random, and with a dash of mystery - not even some prosaic alt-text to dispel the intrigue of the final image......
Is that first one the dials of Gonville and Caius College? Or am I overanticipating my own visit there on Tuesday?
This week Cosmopoet is in sunny 🌞 (no joke!) Cambridge and there are clocks all around: some eat time, while others are on a diet ☺️
March 15, 2026 at 3:42 PM
Is that first one the dials of Gonville and Caius College? Or am I overanticipating my own visit there on Tuesday?
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....)
GUYS GUYS GUYS my incredible colleague, Antoine Borrut, just texted me this pic, the BOOK IS IN HAND, which means you too can have it soon!
Astrology and History in Early Islam, coming out with Edinburgh!
Astrology and History in Early Islam, coming out with Edinburgh!
February 21, 2026 at 11:47 PM
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....)
... 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... !)
February 16, 2026 at 11:56 AM
... 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... !)
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/members/saje...
hcommons.org
February 16, 2026 at 11:09 AM
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/members/saje...
Reposted by Stephen Johnston
