Computus manuscript, with extensive auxiliary materials on cosmology, mathematics, medicine, grammar, prognostication, and related topics. In Latin, with some Old English glosses, on parchment. Written at Thorney Abbey, Cambridgeshire, ca. 1110, by two main and three assisting scribes, in English Caroline minuscule. Gathering [19] added in the 13th century. No visible medieval press mark or ex libris. Second folio: "ciat. dignitatem".

Published catalogues and descriptions: Coxe 1852, 2.5-8; Kauffmann 1975, 55-57 (no. 9); Ker 1957, 435 (no. 360); Hannah and Griffiths 2002, 27-34; Hart 2003 311-345; Watson 1984, 146 (no. 867).

Foliation: vi+177 (+5 Cotton leaves)+v. MS 17 is foliated uniformly in ink by a 17th century hand from 1-177. The five Cotton leaves were originally between MS 17's folios 143 and 144, and are foliated as follows: (a) 1-5 in a 17th century hand, (b) also in a 17th century hand, fol. 81 is labelled "N" and fol. 82 "O", (c) 79-83 in a 17th century hand, (d) 80-84 in modern pencil.

Size and Ruling: 340 x 250 mm. Writing frame 231 to 238 mm high, 102 to 184 mm wide, depending on the nature of text. Single and double columns; variable number of lines. Bounded and ruled in stylus on hair side. Unit of ruling is 5 mm for unglossed and 7 mm for glossed texts. For detailed discussion see Background Essay, "MS 17: Materials and Structure."

Collation: 13, 212, 3-58, 612, 710, 88 (wanting 1 and 2), 9-168, 1715, [18]2 (probably originally 4), [19]12, 207, 218, [22]8 (wanting 8). All gatherings save those in square brackets have medieval signature marks I-XIX, added before gatherings [18] and [19] were inserted in the 13th century. For detailed discussion see Background Essay, "MS 17: Materials and Structure."

Decoration: Single colour calligraphic majuscules, sometimes with tendrils of stylized foliage or simple geometrical ornament, used as initials or display capitals. Numerous tables, diagrams and figurae, most with coloured and decorated frames. Colours: pink, red, yellow, celadon green, dark green, pale blue, cream, golden brown, dark brown. Figural illustrations: calendar contains representations of the zodiac signs Aquarius (fol. 16r), Pisces (fol. 16v), Gemini (fol. 18r) and Leo (fol. 19r); crowned or mitred figure, seated and holding a cup (Annus?) in the middle of the rota of concurrents on fol. 27v. Visible under ultraviolet light are a drypoint sketch for the zodiac sign Libra (fol. 20r), and a crayon drawing of a praying knight in the outer margin of fol. 36r. Between fols. 73r and 127v are a number of brackets for single words or syllables left over at the foot on a column, some with simple leaf decoration, others in the form of a small dragon or dog. For detailed descriptions and discussion see Background Essay, "MS 17: Decoration."

Binding: 17th century. Black leather over medieval boards, probably those used in 13th c. rebinding. Covers have metal corner-plates, roughly square, with bosses surrounded by crown stamping. Front cover has a central metal boss, surrounded by gold-stamped centrepiece. Single stamped and gilt fillet. Paper fly-leaves and pastedowns. For detailed discussion see Background Essay, "MS 17: Materials and Structure."

Summary of contents:

1. Geometry problem (added in the 14th or 15th centuries): fol. 1r.

2. Medicine (I): fols. 1v-2v. Treatise on the four humours; treatise on bloodletting; list of herbs; prognostications of death; weights and measures; medical recipes.

3. Materials related to computus: fols 3r-7v. Abbo of Fleury's acrostic in honour of St Dunstan; grammar of numbers; calendar prognostications; note on world-ages; how to calculate embolisms; lunaria; horoscope; Coena Cypriani; riddles; runic, cryptographic and exotic alphabets; demonstration of cryptography; diagrams showing Easter termini, times of sunrises and sunsets; world-map; table of feriae; tables and texts on degrees of consanguinity; taxonomies of knowledge; "Byrhtferth's Diagram."

4. Computus tables and texts (I): fols. 8r-15v. Rota of the tides; Sphere of Life and Death; computus tables; Byrhtferth's Proemium; diagram of the four elements; summary of computus data (computus graecorum); computistical poetry and short lectiones.

5. Calendar with martyrology: fols. 16r-21v.

6. Computus tables and texts (II): fols. 22r-35r. Tables keyed to calendar; tables for Paschal computation; mathematical operations useful for computus.

7. Cosmography: fols. 35v-40v. Tables and texts on lunar and solar time. Extracts from Isidore of Seville, Abbo of Fleury, and Macrobius.

8. Iatromathematical prognostication: fols. 40v-41r.

9. Mathematics: fols. 41v-58r. Abacus table and related materials; texts on the abacus; fraction table of Hermannus Contractus and abacus tables; Gerlandus Compotista on the abacus, with other texts; notes and tables; rithmomachia.

10. Scientific works of Bede: fols 58v-123r. De temporibus; De natura rerum (glossed); De temporum ratione (glossed).

11. Helperic, De computo: fols 123r-135v.

12. Paschal tables and related materials: fols. 135v-157r. Dionysius Exiguus, Letters to Petronius and to Bonifacius and Bonus; Paschal tables (with annals); Argumenta titulorum paschalium.

13. Miscellaneous materials largely relating to prognostication: fols. 156r-157v. Texts on the zodiac; Sortes sanctorum; ps.-Jerome on the grades of Roman society; ps.-Jerome on the fifteen signs preceding the Last Judgement.

14. Grammar: fols. 159v-175r. Verbs and prepositional prefixes; short texts on orthography and prosody; précis of Priscian.

15. Medicine (II): fols. 175v-177v. Recipes; charm against nosebleed; note on an herb; classification and therapy of fevers; principles of pathology; alphabetical list of herbs, with recipes; diseases and remedies.