Mathematical Treasure: John of Erfurt’s Computus chirometralis

Among a collection of miscellaneous English manuscripts copied in 1443 by a scribe named William is found a computus by a John of Erfurt, who may have been the same John of Erfurt (1250–1340) who wrote about ecclesiastical law and philosophy in Germany. A Computus chirometralis was specifically designed to impart calculation methods for creating calendars and astronomical models through mnemonics. For instance, clergy could use such a text to determine the correct date of Easter. A few pages of this copy are shown below.

A full digitization of its MS 202 is available from the Wellcome Library. Other copies are owned by the University of Glasgow (Sp Coll Bk5-g.22) and Columbia University (MS Plimpton 175).

Reference

Falk, Seb. 2021, August. ‘El Capri Kylex’: A Franciscan Astronomical Mnemonic. Journal for the History of Astronomy 52(3): 267–288. https://doi.org/10.1177/00218286211026210.

Index to Mathematical Treasures