Blog

Facebook greeted me today with this little graphic: Given that this is the radar picture over the UK this morning, it’s not surprising that several Facebook users felt a certain irony. But in what sense is it the first day of summer? As the Met Office explain in a lovely clear blog post, it depends whether you’re talking about the meteorological summer or the astronomical summer.  For our forecasting friends, summer began three weeks ago on 1 June.  (Though as my wife often

Since today is 29th February, a leap-year-themed post is in order.  This one answers the question you’ve all been asking: how are leap years represented on astrolabes? First, a word about the Julian calendar.  Most astrolabes were made before the Gregorian calendar reform (1582), and that made life a bit simpler for instrument-makers.  In the Julian calendar, leap years happen every four years, without exception.  On the other hand, the Gregorian calendar got rid of 3 leap da

A few years ago I enjoyed a blog post in which National Maritime Museum curator Rebekah Higgitt wrote about the “navigation” theme of the new New Zealand passport design.  Higgitt discussed the use of John Harrison’s H1 clock as an illustration in the passport.  She also noted that the description on the New Zealand government website mentioned an astrolabe, which piqued my interest.  I tried to find out more, but the website didn’t include pictures, and none of my Kiwi frien

Apologies for the long hiatus!  I’ve been busy with lots of things, among them the birth of my first child.  I’ll post his horoscope here soon!  But first, here’s a few thoughts I’ve been mulling over for a while… My research centres on scientific instruments.  I study descriptions and images of them, attempt to follow the instructions to make and use them, examine the instruments themselves, and sometimes review or help curate exhibitions of them.  With all this, I spend a l

I wrote this post for the blog of the 24th International Congress of History of Science, Technology and Medicine (iCHSTM), which takes place in Manchester on 21-28 July 2013.  Loyal readers of this blog won’t find much new here, but it’s a fair summary of my research so far. I have modified my views slightly since writing this, mainly about how sophisticated an astronomer the equatorium’s creator was, and how sure we can be about Schöner’s purposes.  I’m looking forward to di

This is a question I’ve been asked several times, and it’s a reasonable one given that this blog is called “Astrolabes and Stuff”, yet I’ve mainly been posting about equatoria.  So I’m going to answer it in this post. First, it’s important to stress the one thing astrolabes and equatoria have in common.  They are both tools, calculating devices.  As such, they simplify (and approximate) tasks that could have been done by geometrical calculation – but the astrolabe and equator

With a free weekend, and fine autumn weather forecast, it seemed a good time to try making my own planetary equatorium. I’m studying a manuscript called The Equatorie of the Planetis, which belongs to Peterhouse, Cambridge.  Much more about that in future posts; for now it’s enough to say that it’s a fourteenth-century instruction manual for the construction and use of a planetary equatorium, a device to compute the position of the planets. Now, I’m no DIY expert, but I pride