Музыкальный барабан от BL Harley 3199, ф.

Musical diagram. Image taken from f. 83 of Miscellany of treatises relating to computus and music, imperfect at the end, including Helperic's 'Liber de computo' (ff. 2-55v); Guido's 'Regulae rhythmicae' (ff. 55v-56), 'Prologus in Antiphonarium' (ff. 56v-58), 'Epistola ad Michaelem (ff. 58v-65) and 'Micrologus' (ff. 79-88v, 91v-94v); 'Musica enchiriadis', excerpt (ff. 65-69v); computus text (ff. 71-74); 'De tonis', dialogue (ff. 74-79); office of the nativity of the Nativity of Virgin Mary’ (ff. 89-91). 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.