Diagrams from BL Harley 3647, f. 45

Two diagrams of the phases of the moon: the left diagram shows the phases of the moon from the point of view of the cosmos and the one on the upper right shows them from the point of view of the earth, in Sacrobosco, 'Compotus'. Image taken from f. 45 of Astronomical miscellany including Sacrobosco, 'De sphaera' (ff. 22-33); Solar tables for 1292-95 (ff. 61-62v); 'Theorica Planetarum' (ff. 81-88); canons for Toledan tables (ff. 97v-119v) and Toledan tables (ff. 120-194v). Written in Latin.

The "BL Harley Manuscript" refers to a collection of medieval manuscripts held in the British Library in London. The Harley Manuscripts are part of the larger collection known as the Harley Collection, which was assembled by Robert Harley (1661–1724) and his son Edward Harley (1689–1741). Robert Harley was a prominent English statesman and bibliophile, and he began amassing a vast collection of books and manuscripts in the late 17th and early 18th centuries.

The Harley Manuscripts are known for their diversity and include a wide range of texts, including historical chronicles, illuminated manuscripts, legal documents, literary works, and scientific treatises. The collection contains over 7,000 manuscripts, and it is considered one of the most important manuscript collections in the British Library.

The Harley Manuscripts are numbered with the prefix "Harley," followed by a specific manuscript number. Each manuscript in the collection has its own unique content and history, and they cover a broad spectrum of topics and time periods. Some of the manuscripts in the collection are beautifully illuminated, with intricate illustrations and decorations.