Tag: Epact

Pre-Modern High Tech

Last month the Washington Post ran a short article by Erin Blakemore on medieval scientific instruments, “Think smartphones are astonishing? Discover the ‘high tech’ devices of the Middle Ages and the Renaissance.” It was a little light on details, but nicely highlighted Epact, an on-line collection of pre-modern scientific instruments. It is easy while away a bit of time browsing the collection.

Erin Blakemore‘s recent article on Epact and pre-modern scientific instruments.

Since the article was illustrated with a Sloane astrolabe from the British Museum, I thought I’d draw attention to another great resource: The Astrolabe: An Online Resource. The website gives you access to every astrolabe in the History of Science Museum’s[1] collection, which is the largest single collection of astrolabes in the world. Astrolabes in the collection range over a millennium and much of the Northern Hemisphere, from the late 9th-century Syria (one of the oldest surviving astrolabes) to the 20th-century England. Most of the instruments date from the pre-modern period. While perhaps not the most flashy of websites, it is probably the single best resource for studying astrolabes.[2]

The Astrolabe: An Online Resource is the best collection of astrolabes available.

Browsing the collection always turns up something new. Just a few highlights:

  • astrolabe 37148, which has amazing engravings of the constellations on the back;
  • astrolabe 48213, which has an ingenious set of gears (the oldest complete gear train) that show the phases of the moon and motion of the sun and moon;
  • astrolabe 45359, which is a so-called “Chaucer astrolabe” because it resembles the illustrations in Chaucer’s Treatise on the Astrolabe, especially the cute little dog’s head star pointer at the bottom of the rete;
  • astrolabe 49687, which is the only surviving spherical astrolabe (there are various descriptions of spherical instruments, but only this instrument survives)
The only (known) surviving spherical astrolabe. It’s truly beautiful.

While I don’t agree with the Washington Post’s author’s conclusion—“a visit to Epact is a glimpse into a bygone world — one in which scientists dared to dream and discover”—I do agree with her earlier statement that spending a few minutes browsing the items on Epact or The Astrolabe: An Online Resource will “make you appreciate the artistry and intricacy of now-obsolete scientific tools or leave you starry-eyed over each instruments’ function and a role.”


  1. The museum formerly known as the “Museum of the History of Science”  ↩

  2. If you need a quick introduction to astrolabes, see my “An Introduction to the Astrolabe.”  ↩