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.

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]

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)

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.”