By Jacqueline Reid-Walsh
Enabling Device
In the first part of this mini-series, I explored the question “what can you do with a piece of string” in terms of being a simple form of pull-tab. Lifting or pulling the string easily enables movement in one direction but the reverse motion is not propelled by the string but is more a falling or pulling back. The examples I explored were both 19th century ones directed to a children’s market. Because I am interested in antecedents I wondered about the use of string as an enabling device in earlier movable books. The famous Astronomicum Caesareum (1540) came to mind with the many intricate threads attached to the volvelles.
Recently some Italian scholars like Giovani Crupi, Pompeo Vagliani, and Eliana Pollone have analyzed the volvelles as a forerunner of modern movable books. As Pollone (2025) states volvelles are one of the earliest mechanisms of paper-engineered book animation, with origins dating back to the medieval manuscript tradition and a long history of supporting learning in technical and scientific books intended for adult readers and students of various ages (Pollone, 2; note 1)
Here what I want to explore is the role of the strings or threads attached to the volvelles and whether they could be considered enabling devices. Working with a facsimile housed at Penn State University, one volume is the reproduction of the book while the second contains scholarly commentary. Consulting the second volume of the facsimile set I read the that “the rotatable cardboard discs, included in this book, could easily be set with the aid of threads attached to them” (2: 42). Later the commentary states regarding an astronomical problem that “[a] thread with a bead can be stretched taut from the centre” (2: 60). Gianfranco Crupi (2016) in “‘Mirabili visioni’: from movable books to movable texts” notes that the silk strings provided a way to accurately determine the positions of the planets and other celestial phenomena. There could be as many as “six rotatable dials, representing central, eccentric, and epicyclical shifts, to harmonize with the Ptolemaic theory of stellar movements, and include up to three silk threads representing ‘fiducial’ lines of reference” (Crupi, 16). Further, “[t]iny pearls attached to the silk threads initially served as sliding indicators on some of the non-rotating circular charts” (Helfand 2002, cited in Crupi, 16).
I wondered how the setting of the thread was done by the interactor since this involved intricate detailed positioning of the thread (s) on multiple discs. For example, in the article “Nebbia di fili”: paper instruments for practical astronomy (1474-1613)” by Giorgio Strano from the Museo Galileo: Institute and Museum of the History of Science, Florence, Strano describes the exactitude of the placement of the volvelles and the strings in order to make intricate calculations. The note reads: “Two larger volvelles are used to position the deferent eccentric circumference in relation to the Earth; the thread coming from point E on the other hand is used to position the epicycle in relation to the equant circumference. Crossing over the two threads coming from the Earth V and from the centre of the epicycle F, the apparent position of the planet is intercepted along the zodiac” (Strano, 90).
Based on this application, I wondered where and how the strings were attached to the volvelles. Examining the facsimile, I realized the threads are attached to the centre of the discs, not at a periphery. The threads were attached to the substrate with a knot or stitch and formed the fulcrum or central axis of the volvelles. Michelle Gravelle, Anah Mustapha, and Coralee Leroux observe that usually the components bear text or illustrations and are anchored to the page with string. They observe that this invention of Matthew Paris’s “allowed readers to turn the disk and align it with their bodies, thus making it easier to read the dates” (Note 2).
Reading this I wondered how the readers turn the disc; do they hold onto the edge? Looking at the facsimile I noticed that on occasion there is a paper tab protruding from the side of some discs.
Touching the threads, and the multiple discs and turning over the pages I realized that the strings create a silky textured effect on top of the disc and that the layers of discs served to mask the sewing of the thread into the thick paper.
When only a single disc, the knot or stitch can be felt more than seen on the reverse of the paper sheet. Perhaps this opaque design served to further enhance the majesty and mystery of the large-scale images.
At the same time some of the functional threads or strings have beads and are beautiful objects when set against the elaborate volvelles. Were they also subjects of contemplation and meditation?
My questions here concern how widespread was the knowledge of these intricate instruments that required strings to be fully functional? Did these devices continue to be included in later editions? We know that the practice of using volvelles as interactive educational devices continued throughout the centuries (see Vagliani 2025) but the presence of strings is not apparent.
My next question concerns the use and possible misuse of the strings. In terms of the design, did the arrangement of the strings enable other uses? Here I refer to Suzanne Karr Schmitt’s book Altered and Adorned: Using Renaissance Prints in Daily Life (2011) where she discusses how some viewers interacted with prints in nontraditional ways that could be considered “misuse” or “abuse” (Karr Schmitt, 11).
I am not referring to her specific context which involves explicit censorship or blasphemy where users physically damaged the prints or marked margins and images with critical words and graphical additions. I am not a specialist, but I do not know of any volume with volvelles that have been altered in such a way. Rather, I am speculating that the beautiful strings that had to be laid out on top of the volvelles by the interactor invited other ways of engaging with them apart from the intended use. One idea I had and dismissed was whether you could use the strings to move the volvelle, but this is difficult to achieve and damages the device. Rather according to Valiani and Crupi there were occasional tabs affixed to the periphery of the volvelles. I am still pondering possible uses of string in later volvelles such as attaching it to the periphery to activate the disc. Could this be a new sub project?
Note 1: In note 27 Pollone cites Rubin about terminology. In the absence of a standardized vocabulary, the terms dischi mobili (“wheels”) and volvelle are often confusing and sometimes used interchangeably. The distinction, as adopted here, can be outlined as follows: volvelle refers to those mechanisms—typically associated with combinatory systems—composed of “rotating paper or membrane discs, shaped and overlapping and fixed to the page with one or more pins, allowing each disc to be independently rotated around its axis” (Crupi 2019b, 2); dischi mobili (or “wheels”), on the other hand, may refer either to the individual rotating components of a volvelle, or to specific mechanisms—historically more recent—consisting of: “An illustrated disc of paper or cardstock sandwiched between two adjoining pages and secured by a paper disc or metal grommet. Die-cut holes in the top page allow for the illustrations drawn around the wheel to show through the holes” (Rubin 2023, 101).
Note 2: See also Daniel K. Connolly, “Imagined Pilgrimage in the Itinerary Maps of Matthew Paris,” Art Bulletin 81, no. 4 (December 1999), 611.
Works cited
Crupi, Gianfranco. 2016. “‘Mirabili visioni’: From Movable Books to Movable Text.” JLIS.It 7 (1):25-87.
Gravelle, Michelle, Anah Mustapha, and Coralee Leroux. “Volvelles.” In Archbook https://drc.usask.ca/projects/archbook/volvelles.php. Accessed April 20, 2025.
Helfand, Jessica. 2002. Reinventing the Wheel. New York: Princeton Architectural Press.
Karr Schmitt, Suzanne with Kimberly Nichols. 2011. Altered and Adorned: Using Renaissance Prints in Daily Life. New Haven: Yale University Press.
Pollone, Eliana. “Raise or Turn, Follow the Story and Admire Flaps and wheels in Italian Children’s Books of the 1930s and 1940s.” JIB 4. 2025 pp. 1-17, note 27
Strano, Giorgio. 2019. “Nebbia di fili: paper instruments for practical astronomy (1474-1613)” in Pop-app: science, art and play in the history of movable books from paper to apps. Ed. Giovani Crupi and Pompeo Vagliani. 87-97. Turin: Tancredi di Barolo Foundation.
Vagliani, Pompeo. “Playful Science: Games, Didactic Resources, and Interactive Books.” JIB 4. 2025 pp. 52-61.
