How about this for a truism: a book is a book, and something that is not a book is not a book. This post will knock your socks off if you are inclined to affirm this statement, because in medieval times a book could be so much more than that. As it turns out, tools were sometimes attached to manuscripts, such as a disk, dial or knob, or even a complete scientific instrument. Such ‘add-ons’ were usually mounted onto the page, extending the book’s primary function as an object that one reads, turning it into a piece of hardware.

Adding such tools was an invasive procedure that involved hacking into the wooden binding or cutting holes in pages. In spite of this, they were quite popular in the later Middle Ages, especially during the 15th century. This shows that they served a real purpose, adding value to the book’s contents: some clarified the text’s meaning, while others functioned as a calculator or, astonishingly, allowed the reader to tell time. These fascinating add-ons – which are really not that different from the apps on our smartphones – turned a static handwritten book into an interactive object.

The Volvelle

A volvelle is an instrument that consists of one or more rotating disks mounted on the page. Volvelles allowed the reader to make a variety of complex calculations, such as the position of the sun and the moon, or the precise date of Easter – which was, like the volvelle, a moving feast. The one seen in Fig. 1 contains no less than three revolving disks, which are pinned to the page in a central point: two show the cycle of sun and moon (note the charming depictions at their pointers), while a third presents the Zodiac.

In spite of its simplicity, the device provides a surprising wealth of data, which could be read if one knew how to interpret the dials. However, volvelles were not always crude instruments providing dry data. Some are actually a pleasure to look at (Fig. 2). Others added an entertaining touch to the moving parts. The one in Fig. 3, for example, calculates the date of Easter, a popular application of the volvelle, but in this case the answer is pointed out by a spinning lady.

The oldest volvelles are connected to the scientific explorations of Raymond Lull, a thirteenth-century scholar, who introduced the clever device from Arabic scholarly culture. It explains why the earliest volvelles date from the 13th century (there are no older manuscripts that hold them, as far as I am aware), but also why the oldest ones are found in books holding works by Raymond Lull. These oldest specimens are less sophisticated: they have a limited number of disks and present less data on and around the dials (see a Lull specimen from the early 14th century here).

Such crude medieval computers could make a page very bulky. It is surprising, however, how much volume a volvelle could take up without compromising how well the book could be handled.The one I encountered in an archive some time ago even makes use of pieces of wood, giving it the appearance of a real instrument, but also adding a certain clunkiness (Fig. 4).

Cogwheel

Volvelles are not the only instruments mounted onto the medieval book. Fig. 5 shows a page from a manuscript containing various texts about fortune telling. The page holds a text on Geomancy, which is a method of divination that allowed someone to calculate one’s ‘key number’. Random rows of numbers were drawn up and marked down (as seen on the page), after which they were connected by lines. The number you ultimately ended up with was then looked up in a table with lunar and solar information, which was also included in the manuscript (image here).

There was another method to calculate this number: by turning a wheel (information here). It is here that the Oxford manuscript becomes relevant for us. Remarkably, the user of the book carved a hollow space into the wooden front board of the binding and fitted a pair of cogwheels into it (Fig. 6). Turning these produced the number that could subsequently be looked up in the table.

The last word: sundial

The last example of an instrument that was added to a book also has to do with the sun. Like an iPad, the book in Fig. 7 has a smart cover. The front of the sheepskin bookbinding is not filled with blind-stamped decoration, as was often the case, but rather a sundial was pasted on it. The reader could put the book in the sun and place a stylus on the cover, which would reveal what time it was. While it may not have been a very practical clock, the cover reveals that it was likely used to this end: the ‘footprints’ of the stylus are still visible (note the small circle and the black stain near the letters IHS, at the bottom). Moreover, the severity of the stain suggests the book was frequently used to tell time.

Just like our modern smartphones, the medieval book could be a versatile tool that combined contents with an untold number of applications – giving the scriptorium the feel of an App Store.