<p style='text-align: justify;'>Cambridge, Fitzwilliam Museum, MS McClean 166 (hereafter MS McClean 166) contains three popular astronomical and computistical texts: the <i>Algorismus</i>, <i>Tractatus de sphaera</i> and the <i>Compotus</i>, all by Johannes de Sacrobosco, a popular medieval scientific author. The Sacrobosco texts are found on ff. <a href='' onclick='store.loadPage(27);return false;'>12r-71v</a> of MS McClean 166, and the remaining leaves contain a calendar, computus tables, annalistic notes, a medical recipe, and a treatise on the use of the quadrant, a tool typically used for finding the altitude of a celestial body. Both the treatise on the quadrant and the works of Sacrobosco are accompanied by neatly illustrated diagrams to help the reader interpret the concepts discussed in the texts. </p><p style='text-align: justify;'>The date and location of production of the manuscript can be determined with relative accuracy due to the annalistic material and the calendar. The list of important calendrical, computistical, and time-reckoning information on f. <a href='' onclick='store.loadPage(5);return false;'>1r</a> suggests that the notes were made c. 1279. The Julian calendar begins with the birth of Jesus, and the notes on that leaf state that 1279 years have elapsed since that event. Jesus is traditionally believed to have died in his 33rd year of life, and the notes also record that it has been 1247 years since he was crucified. Subtracting the year 1279, from the number of years stated to have passed since the creation of the world, 6479, gives a creation date for the world c. 5200 BCE, which also accords with calculations made for the age of the world by St Jerome and Gregory of Tours. The annalistic information on f. <a href='' onclick='store.loadPage(26);return false;'>11v</a> includes computistical calculations for the years 1275-1386 and annals for the years 1274 and 788. Taken together, the time-reckoning calculations and the annalistic material point to a date of production in the late 1270s. As M. R. James noted in his <i>Catalogue</i> record for MS McClean 166, the location of production can be inferred through details in the calendar found on ff. <a href='' onclick='store.loadPage(147);return false;'>72r-77v</a>; M.R. James noted that in addition to the major feasts typically found in almost every medieval calendar, the calendar in MS McClean 166 includes several entries for local saints associated with the city of Verdun and the wider region of north-eastern France, which suggests that the manuscript originated from that locale. </p><p style='text-align: justify;'>MS McClean 166 has been trimmed and rebound since it was made and the leaves are not in their original order. MS McClean 166 retains an original medieval foliation sequence, written in ink in the typical medieval form of Hindu-Arabic numerals in the upper right-hand corner of the rectos, but the numerical sequence indicates that what was once the final quire in the volume is now instead presented as the first. The first quire (ff. <a href='' onclick='store.loadPage(5);return false;'>1-11</a>, original 5th leaf missing) has the medieval folio designations ff. 69-80 (69 largely trimmed away, 73 absent due to loss of 5th leaf after medieval foliation), indicating that it originally followed the present Quire 7, the final quire in the manuscript, which ends with the medieval designation '68' on what is now f. <a href='' onclick='store.loadPage(157);return false;'>77</a>. It is not clear why the final quire was displaced, particularly as it means that the Sacrobosco texts, which make up the majority of the volume, now begin later in the codex. </p><p style='text-align: justify;'>Dr Sarah Gilbert<br /> Project Cataloguer for the Curious Cures in Cambridge Libraries Project<br /> Cambridge University Library</p>
