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!
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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
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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.
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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.
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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)
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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)
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@SchemeOfHeaven Not that I only follow you for alexboxer.com/astrolabe/ and utterly identify you with it! (6/5)
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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)
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@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)
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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
