Curator Emeritus at Oxford's History of Science Museum; historian of science, technology and mathematics, particularly instruments and material culture.
Oxford, UK
Joined May 2011
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Event for the @OCISOxford and @HSMOxford exhibition "Lines of Faith: Astronomy and the Art of the Astrolabe in the Islamic World": Joumana Medlej @joumajnouna leads a study day on Abjad numerals - Saturday 17 May. Full details at eventbrite.com/e/when-letter…
Stephen Johnston retweeted
We are pleased to host an Open House for University of Oxford Freshers (undergraduate-level and graduate-level students) on Saturday, 30th November.
To attend, please register by noon on Friday 29th November.
Registration link: oxcis.ac.uk/form/ocis-open-a…
New uses for @SchemeOfHeaven's online astrolabe: recreating an astrolabe plate from @HSMOxford: hsm.ox.ac.uk/collections-onl…. The original might look more aesthetic than functional but its combination of "Regiomontanus" houses for 24° and 30° is revealed by my DIY photo editing.
The giveaway that these are Regiomontanus houses comes from the fact that the two sets of arcs all intersect on the equator - even though one is upside down compared to the other!
No time right now to look systematically, but perhaps double latitude plates with Regiomontanus (fixed equatorial) houses were more common than anyone could reasonably suppose? Here's another Indo-Persian example from @HSMOxford: hsm.ox.ac.uk/collections-onl…
#astrolabe #astrology
New profile pic and banner image after an inspiring morning @WhippleMuseum with Josh Nall and a (reworked) medieval astrolabe - as well as a digital microscope.
Nice surprise the other day at the Whipple Library @hpslib to find myself in 50 year old footsteps. Opened up a box with a 1588 ed of Giovanni Paolo Gallucci, Theatrum mundi - to find Owen Gingerich had already been here.
@DrKarrSchmidt He evidently discovered a misplaced volvelle #MovableMayhem at p. 231 and arranged for it to be moved to the right place elsewhere in the volume. The transfer was unambiguously documented by keeping a photocopy (photostat?) of the offending assemblage.
Stephen Johnston retweeted
New #astrolabe feature: A "presentation mode" button (small gray triangle, upper-right). This lets you access the toggle switches at the bottom of the page without having to scroll away from the astrolabe. Thank you @StephenHSM for the suggestion!
alexboxer.com/astrolabe
So could there be two switches: one to turn on the sun and another for all the rest of the classical planets? That would make for a satisfying modern version of the historical instrument, while still enabling the cool equatorium extension. (4/5)
And (I’ve started so I’ll finish) what about a switch for the unequal hour lines? Would be great to demonstrate them in their traditional place on the plate – and handy as a prompt to introduce planetary hours. 🙏🙏🙏🙏 Pretty please? (5/5)
@SchemeOfHeaven Not that I only follow you for alexboxer.com/astrolabe/ and utterly identify you with it! (6/5)
Two things would be invaluable for an astrolabe demonstration I’m doing at an online workshop “When the Stars Tell Time” in early July. (2/5)
@SchemeOfHeaven The house additions you made recently have been super useful. Any chance that you might be prevailed on to further tweak an already stellar resource? 🙏🙏🙏🙏(1/5)
Stephen Johnston retweeted
Returning to my online #astrolabe after several years to add Regiomontanus and Alchabitius cusps. Have to remind myself how these are defined. I take Regiomontanus' Tabulæ Directionum, Prob. 14 as my guide. Should have results soon. @StephenHSM @Seb_Falk
