Medieval chart of the decemnovenale cycle. 1230 extract from De sphaera mundi, by the Parisian astronomer and monk Johannes de Sacrobosco (circa 1195-


Medieval chart of the decemnovenale cycle. 1230 extract from De sphaera mundi, by the Parisian astronomer and monk Johannes de Sacrobosco (circa 1195-1256), with a chart showing the decemnovenale cycle, the cycle of epacts, and the cycle of the 'claves.' De sphaera mundi is a short astronomy textbook that was widely read and influential in Europe as an introduction to astronomy. Sacrobosco is also known for writing a short introduction to the Hindu-Arabic numeral system, which became the most widely read introduction to the subject in the later mediaeval centuries. He also correctly described the defects of the then-used Julian calendar and recommended what was essentially the Gregorian calendar.


Size: 2729px × 3850px
Photo credit: © Renaissance and medieval manuscripts collection/NEW YORK PUBLIC LIBRARY/SCIENCE PHOTO LIBRARY / Alamy / Afripics
License: Licensed
Model Released: No

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