Bat Books: A Catalogue of Folded Manuscripts Containing Almanacs or Other Texts by J. P. Gumbert (review)

In New York City, children used to be taught the 'subway fold': the New York Times can be re-folded so that the creases fall along intercolumnar gaps, to make a small packet that can easily be held in one hand so that the reader can use the other to grasp a subway strap. The fold was a way of repackaging the newspaper for commuters. Its logic resembles that of a late medieval parchment folding technique, the bat book, which likewise repackages texts for the traveller.

Bat books consist of parchment sheets folded into compartments, which have to be unfolded in order to be read. Each rectangular leaf has a tab on one edge, and these tabs are gathered together with stitches so that the leaves can be bound together. Because they are clearly designed to be portable, they sometimes appear as 'vademecum' in catalogues. The bat book is distinct from the girdle book (Beutelbuch), which is a codex bound with extra-large (usually leather) coverings over its boards, so that it can be hung from a belt. Bat books, too, can be carried on a belt, but they are not codices. Peter Gumbert calls them 'bat books', 'because when in rest they hang upside-down and all folded up, but when action is required they lift up their heads and spread their wings wide' (p. 19).

This unusual book type had been ignored until this laudable study—Gumbert's final book—brought them to view. Gumbert (1936–2016) was emeritus professor of western palaeography and codicology at Leiden University. He did the codicological world a service by identifying sixty-three bat books, with fifty-nine of them surviving and the other four known from catalogue records. Whereas writing a catalogue of a particular library or collection has its challenges, one at least knows when one is finished, because the elements in a given collection are, except in unusual circumstances, finite and circumscribed. However, when one is cataloguing every example in the world of X, one never knows if the list is complete. A catalogue of this sort will shake more examples out of the woodwork, because the publication itself allows people to recognize what might have previously been too obscure to name. Already one new magnificent example has come to light: a late English almanac with a folded volvelle, housed in the National Library of Scotland, which is noted in the recent article by Karen Overbey and Jennifer Borland about a bat book in the Morgan Library ('Diagnostic Performance and Diagrammatic Manipulation in the Physician's Folding Almanacs', in The Agency of Things in Medieval and Early Modern Art: Materials, Power and Manipulation, ed. by Grażyna Jurkowlaniec, Ika Maryjaszkiewicz, and Zuzanna Sarnecka (New York, 2017), pp. 144–56). Indeed, they are not the only theoretically minded voices from America who have fallen into the fold of an old-school European codicologist while cornering sharply on the material turn. Another who revels in meaning-making around the operations of using bat books is Chelsea Silva ('Opening the Medieval Folding Almanac', Exemplaria, 30 (2018), 49–65). Unfortunately, none of them adopts Gumbert's batty term.

Many bat books contain calendars and ancillary texts, plus something else, but that 'something else' is highly variable. Gumbert has organized the manuscripts by their content, but also in roughly chronological order, roughly because only a handful of them is securely dated or datable. Chapter 1 covers the oldest bat books, beginning with one made at Glastonbury Abbey around 1265 (Cat. 1), listing relics and place names of the area. Cat. 6, made around 1292 for use in Split (Dalmatia), contains elaborate illuminations, although where and when these paintings were added is a matter for debate. Cat. 7, recently purchased by Yale University, lists lucky, unlucky, and perilous days, as well as...