The world in your hand
Meet the astrolabe: a two-dimensional model of a three-dimensional world – ours. The instrument was used to locate and predict the position of sun, moon and planets, but it was also great for determining the precise time at a given location. As a recent count of medieval specimens shows, c. 800 survive today, suggesting that the instrument was quite popular in medieval times.
What’s so great about these objects is that they are crossing the divide between books and other medieval artifacts. There are metal versions, plain like the second image above; and more complex ones with turnable disks (see an example here). But the object also appeared as drawings in books, as the top image shows. While the manuscript drawing above is unusually detailed and realistic, likely meant for real calculations, many book versions are far less complex – merely illustrating the text. A precision instrument contained on a flat page: it’s an unusual encounter for the historian of the medieval book.
Pics: the metal disk is a Hebrew astrolabe kept in the London Science Museum; the manuscript is Bruges, Stadsbibliotheek, MS 522, 14th century. Read some illuminating interviews with Astrolabe experts here. Feel like making one yourself? Check this out.