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The Collation

As three of you immediately identified in your comments, last week’s crocodile mystery was the fastening in the center of a volvelle, holding the various layers in place and allowing them to turn:

volvelle from Cortes’s Breve compendio, leaf 37r (click to enlarge)

Volvelles are paper wheels that are fastened to a leaf so that the discs spin independently. Some of the earliest volvelles were used for prognostication; Ramon Llull is credited with bringing the volvelle to the West in the late thirteenth century for use in his Ars Magna.  Suzanne Karr describes the system of two discs of letters on top of a third layer as one that did not simply aid memory but produced new knowledge:  

  1. Suzanne Karr, “Constructions Both Sacred and Profane: Serpents, Angels, and Pointing Fingers in Renaissance Books with Moving Parts” Yale University Library Gazette 78:3/4 (April 2004), p. 103.
  2. For a quick introduction to Llull and his volvelles, see Brooke Palmieri’s post, “An Introduction to Paper Computing.”
  3. And many thanks to Whitney and to Chad Black for help in researching volvelles and in translating Cortés’s Spanish!


As a footnote, it’s probably worth mentioning that Anthony S. Drennan has proposed a standard for the bibliographic description of volvelles and other moveable diagrams in the most recent issue of The Library:

Drennan, Anthony S. “The Bibliographical Description of Astronomical Volvelles and Other Moveable Diagrams.” The Library 13.3 (2012): 316-339.

Aaron Pratt — December 11, 2012


The most spectacular volvelles are those in Peter Apian’s Astronomicum Caesareum

Thony C — December 11, 2012


Yes, that Drennan article is an eye-opener.
For work on volvelles, see also Richard Cunningham, “Acidental Technologies,” Digital Studies / Le champ numérique:

Kathleen Lynch — December 12, 2012


If anyone is interested in more contemporary volvelles, there’s a great book titled Reinventing the Wheel by Jessica Helfand. Makes a lovely coffee table book, and you can learn about What Your Corn Can Do to Help Win the War (one of the more amusingly-named examples).

Michelle Sellars — December 13, 2012


Peter Apian’s Cosmographicus Liber (over 30 printed editions before 1610) provides the best introduction to the capabilities of simple astronomical volvelles. But beware, although his Astronomicum Caesareum has quite rightly been described in recent years as ‘the most beautiful scientific book ever published’, anyone trying to decipher its huge, spectacular and complex volvelle diagrams should heed King Lear when he said ‘that way madness lies’.

Tony Drennan — December 14, 2012


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