An opera omnia of the Welsh physician and astronomer Lewis of Caerleon (d. in or after 1495), representing the largest and most complete collection of his astronomical and mathematical works. Written under Lewis's supervision, the manuscript contains self-referential rubrics (�per me Lodowycum Caerlyon�) and personal annotations in Latin and signatures of his name in the vernacular (�Lewys�) throughout. The manuscript was carefully planned, featuring astronomical tables and diagrams in a layout and style that closely resemble those of other Lewis of Caerleon manuscripts (e.g. Royal MS 12 G I), and was executed in an unusually large size, suggesting that it was a presentation copy. Lewis is known to have donated copies of his tables of eclipses to colleges in both Cambridge and Oxford. This manuscript contains calculations for Cambridge (pp. 49 and 55), and so it may have been intended for the University of Cambridge. Lewis's works focus especially on lunar and solar eclipses and equinoxes, but also deal with mathematical subjects related to astronomy. His calculations are based on those of leading English astronomers such as Simon Bredon (d. 1372) and Richard of Wallingford (d. 1336), Abbot of St Albans, both fellows of Merton Coll� Text continues in the catalogue record