Eclipses from BL Harley 531, ff. 11v-12

Diagrams of eclipses, with the earth in the centre and the sun in the outer orbit. In the upper diagram, labelled 'Eclipse of the moon', the earth casts its shadow on the moon, while in the diagram below, labelled 'Eclipse of the sun', the moon casts its shadow on the earth. Image taken from ff. 11v-12 of Tractatus de sphaera (index De sphera), in a mathematical and scientific miscellany. 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.