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Cambridge University Library


The Equatorie of the Planetis project was a 2-year collaboration (2012-14) between Peterhouse, Cambridge University Library and the Whipple museum to digitise an astronomical document dating from the late 14th century, and to produce an innovative virtual model of the equatorium.

The Equatorie of the Planetis (MS 75.I) manuscript is from the Perne Library, Peterhouse. It describes a scientific instrument which accurately calculates the position of the five planets known at the time (Mercury, Venus, Mars, Jupiter and Saturn), together with the Sun and the Moon. The Equatorie was first uncovered in the 1950s by PhD student Derek Price and was thought to be written by Chaucer. Price had decided to try to recreate the instrument and produced a six foot wide model which had been on display in the Whipple museum. It was moved during a refurbishment and had remained forgotten until PhD candidate Seb Falk rediscovered it in 2012.

The project to digitise the document was funded by the generous donors to Peterhouse. This funding enabled Cambridge University Library to produce high quality digital images of the manuscript. These were  accompanied by a transcription and detailed explanatory notes produced by researchers Professor Kari Anne Rand and Seb Falk. Rand's study of the manuscript ruled out Chaucer as the author -  a comparison of writing on a manuscript held in the Bodleian Library, identified the author as John Westwyk, a Benedictine monk of Tynemouth Priory and St Albans Abbey.

Seb Falk also worked with programmer Benjamin Blundell to create a virtual 3D model, complete with instructions, so that people can use the equatorium. It can calculate the positions of the planets to within one degree of accuracy, and has been compared to both the PyEmphem and the NASA Horizons project. The virtual model is embedded in the Digital Library alongside the manuscript.

Key institutions

Cambridge University Library, Peterhouse, Whipple museum

Key people

Scott Mandelbrote, Director of Studies in History and Perne Librarian at Peterhouse, Cambridge oversaw the project.

Seb Falk, HPS, University of Cambridge, and Kari Anne Rand, Professor Emeritus, University of Oslo,  contributing authors.

Professors Rod Thomson , University of Tasmania and Prof Liba Taub, HPS, University of Cambridge, project advisers

Benjamin Blundell, Section9, programmer who designed the virtual model.


Professor Joe Pesce and donors to Peterhouse.


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