Sermones aurei de Sanctis Fratris Leonardi de Utino Venice: Franciscus Renner, de Heilbronn, with Nicolaus de Frankfordia, 1473. (Goff L-152) Call number: ExI 5428.579

Although this incunable was rebound in 1945, a remnant of the original 15th century binding was laid in — a bookmark with a rotating column-indicator. ❧ Other examples are known, such as:
• Harvard University, Houghton MS Typ 277, 12th c. [link to image] Register bookmark with adjustable dial set between column II and III (i.e. col. B verso and col. A recto [not pictured]) [See the recent posting discussing this Houghton example in the blog medievalfragments (Institute for Cultural Disciplines, Universiteit Leiden)].
• Medieval Rotating Column-Indicators: An Unrecorded Second Example in a Thirteenth Century Bible (Cambridge, Corpus Christi College Ms 49) by Richard Emms published in Transactions of the Cambridge Bibliographical Society, Vol. 12, No. 2 (2001), pp. 179-184 [Stable URL: http://www.jstor.org/stable/41154907]