Manuscript Number: ljs026

Version: Mar/30/2001

Johannes Sacrobosco, Algorismus [With] Tractatus de Sphaera, in Latin. Manuscript on Vellum.

[Italy, s. XIIImed]

31 folios, lacking one leaf after f. 16, collation: I10, II10 (-1), III10 (+2), quire II signed ‘ii’, 1 column, 25 lines, written in black ink in a early Gothic script, seventeen painted initials and ten astronomical diagrams, rebound in 1997 in black morocco with gilt panels and corner-pieces, 180 x 134 (125 x 80) mm.

Incipit: Algorismus/Omnia que a primeva rerum origine…/…oportimo habetia[ ]ita vas… [def]


  1. Brother Pietro di Santo Giovanni, a Franciscan student of physics from the province of Florence, his signature with a date of 1399 on folio 9v.
  2. Acquired from Sotheby’s, 2 December 1986, lot 35.


Johannes Sacrobosco (Halifax Late 12th Century-1256), born as John of Hollywood, wrote three texts of which two are in this manuscript. (See LJS 77 and 216 for all three texts). These two texts are among the greatest of the thirteenth century. He combined some of the ideas of Ptolemy, al-Batt?n? (Albategnius d. 929) and al Fargh?n? (Alfraginus c. 833). He was also the first to calculate the discrepancy between the Julian calendar and the actual solar year and he suggested a solution that was extremely similar to the one eventually devised by Pope Gregory XIII more than 350 years later. His works were popular well into the 17th Century

The two manuscripts in this volume are almost contemporary with the life of Sacrobosco. The text includes a study of the fundamentals of arithmetic and his best-known treatise on the heavenly spheres. The Tractatus de Sphaera was still the standard work on cosmography in the 16th century. The Algorismus or Tractatus de Arte Numerandi uses Arabic numerals in the text and was a major influence on their adoption in the modern world. Both texts are illustrated with diagrams in red and black (TK 990, 991).


Sotheby’s, 2 December 1986, lot 35.

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