Rotating bookmarks were a kind of
bookmark
A bookmark is a thin marking tool, commonly made of card, leather, or fabric, used to keep track of a reader's progress in a book and allow the reader to easily return to where the previous reading session ended. Alternate materials for bo ...
used in medieval Europe. They were attached to a string, along which a marker could be slid up and down to mark a precise level on the page. Attached to the marker was a rotating disk that could indicate the column (usually numbered one to four, indicating the two columns on the left-hand page, and the two columns on the right-hand page).
About 30 such rotating bookmarks have been recorded in libraries in
continental Europe, and another half a dozen in England.
References
*J. Destrez, ''L’outillage des copistes du XIIIe et du XIVe siècles'', in ''Aus der Geisteswelt des Mittelalters'',
Martin Grabmann festschrift, 1935, 19–34
*R. Emms, ''Medieval Rotating Column-Indicators'', Transactions of the Cambridge Bibliographical Society, XII, 2001, 179–l-84).
External links
History of Bookmarks
Book terminology