Stephen Johnston
@stephenaj.bsky.social
Curator Emeritus at Oxford's History of Science Museum; STEM historian, particularly instruments and material culture - current research focused on astrolabes and astrology in medieval and renaissance Europe. (Disclaimer: focus known to wander.)
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!
November 13, 2025 at 4:15 PM
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!
Lorch (1942-2021) was then based at #Manchester #UMIST and a fellow student of medieval astronomy – in his case mostly Arabic but also Latin. His copy of Goldstein's edition of this set of tables is a nice reminder that even the most apparently austere scholarship is personally underpinned.
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November 7, 2025 at 9:29 PM
Lorch (1942-2021) was then based at #Manchester #UMIST and a fellow student of medieval astronomy – in his case mostly Arabic but also Latin. His copy of Goldstein's edition of this set of tables is a nice reminder that even the most apparently austere scholarship is personally underpinned.
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A real surprise and delight to unpack what I thought was an anonymous purchase and instead discover it was an author’s dedication copy, addressed to Richard [Lorch] “in appreciation of a pleasant visit with you in Manchester”. It was signed by “Bernie” almost exactly 50 years ago.
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November 7, 2025 at 9:29 PM
A real surprise and delight to unpack what I thought was an anonymous purchase and instead discover it was an author’s dedication copy, addressed to Richard [Lorch] “in appreciation of a pleasant visit with you in Manchester”. It was signed by “Bernie” almost exactly 50 years ago.
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I’m currently working with Josefina Rodriguez-Arribas on the mathematics of early 15th-century Hebrew astrology and decided it would be useful to have an edition of a key primary source to hand.
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November 7, 2025 at 9:29 PM
I’m currently working with Josefina Rodriguez-Arribas on the mathematics of early 15th-century Hebrew astrology and decided it would be useful to have an edition of a key primary source to hand.
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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
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#Hebrew #medieval #astronomy #tables
#Manchester
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November 7, 2025 at 9:29 PM
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
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#Hebrew #medieval #astronomy #tables
#Manchester
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That's funny - I was also struck by the incongruously modern engraved lettering of Venus the last time I was in Dresden, and so took almost exactly the same image. The contrast between the sumptuous original decoration and this later identification of the planet is pretty extreme....
October 14, 2025 at 5:08 PM
That's funny - I was also struck by the incongruously modern engraved lettering of Venus the last time I was in Dresden, and so took almost exactly the same image. The contrast between the sumptuous original decoration and this later identification of the planet is pretty extreme....
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-...)
October 14, 2025 at 8:25 AM
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-...)
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.
October 5, 2025 at 5:49 PM
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.
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!
September 25, 2025 at 8:39 PM
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!
But it's also out in the wild in print - and arrived in Oxford literally this morning!
September 24, 2025 at 12:05 PM
But it's also out in the wild in print - and arrived in Oxford literally this morning!
This is ahead of an introductory online course in a fortnight. I hope it will make me better appreciate and interrogate historical instrument engraving - though I'm not expecting to display my new-found abilities any time soon.
September 19, 2025 at 6:51 PM
This is ahead of an introductory online course in a fortnight. I hope it will make me better appreciate and interrogate historical instrument engraving - though I'm not expecting to display my new-found abilities any time soon.
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.)
September 19, 2025 at 6:51 PM
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.)
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.
September 14, 2025 at 10:10 AM
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.
Yes, I imagined that the picture wasn't your choice, and I'm curious why it was chosen - especially since the other side of that astrolabe is almost certainly much closer to the kind of instrument that would have circulated from Al-Andalus to northern Europe.
August 25, 2025 at 8:29 PM
Yes, I imagined that the picture wasn't your choice, and I'm curious why it was chosen - especially since the other side of that astrolabe is almost certainly much closer to the kind of instrument that would have circulated from Al-Andalus to northern Europe.
Oops. When I say "this tympan", it might conceivably help if you could actually see it in all its hemisphere-spanning pomp. (Though it's not as precisely executed as became the royal style, eg in the Shah Abbas II astrolabe. Almost freehand here, which might be worth further thought and comparison.)
August 24, 2025 at 10:33 AM
Oops. When I say "this tympan", it might conceivably help if you could actually see it in all its hemisphere-spanning pomp. (Though it's not as precisely executed as became the royal style, eg in the Shah Abbas II astrolabe. Almost freehand here, which might be worth further thought and comparison.)
In the context of sacred kingship it's suddenly incredibly striking that the throne of this astrolabe is utterly empty but the lines celebrating Abbas as "the just sultan, the greatest, the glorified Khāqān, master of the sovereigns of the Turks, the Arabs, the Persians" are relegated to the back.
August 24, 2025 at 10:17 AM
In the context of sacred kingship it's suddenly incredibly striking that the throne of this astrolabe is utterly empty but the lines celebrating Abbas as "the just sultan, the greatest, the glorified Khāqān, master of the sovereigns of the Turks, the Arabs, the Persians" are relegated to the back.
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.
August 24, 2025 at 10:12 AM
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.
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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July 8, 2025 at 9:41 PM
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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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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July 7, 2025 at 11:28 AM
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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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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July 7, 2025 at 11:26 AM
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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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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July 7, 2025 at 11:25 AM
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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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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July 2, 2025 at 12:57 PM
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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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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July 2, 2025 at 12:54 PM
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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July 2, 2025 at 12:53 PM
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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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.
July 1, 2025 at 7:20 AM
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.