Volvelles

The word volvelle comes from the Latin volvere, meaning “to turn.” Volvelles were paper instruments made from layered discs fixed with a rivet. They were bound into books or mounted as loose sheets and appeared widely in astronomical, medical, and calendrical texts across Europe from the late medieval period through the early modern era.

Their circular form suggests motion. Concentric rings act as clear affordances, inviting rotation, while fixed centres and pointers serve as signifiers that guide where to hold. Each disc has a distinct role, and its position within the stack communicates its function. Outer rings tend to frame time or context; inner rings reveal relationships. Navigation in a volvelle is spatial rather than sequential. Instead of moving forward or backward, the reader moves around. Information is revealed through alignment, overlap, and proximity. Cause and effect are immediate. This clarity of interaction is what gives volvelles their lasting relevance. With minimal instruction, the object explains itself through its structure, rewarding exploration and reinforcing understanding through repeated gestures.

Volvelles expressed an important idea: knowledge could be operated, not only read. Much like later calculators and computers, they were simple analogue machines made from paper. Information lived on the edges of discs, along radii and arcs, and was revealed or concealed through rotation. Understanding emerged through alignment and movement.

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Lunar Volvelle

The lunar volvelle allowed a reader to track the movements of the Sun and Moon and to understand their changing relationship across the year. Clockwise and anticlockwise motion reflect how celestial bodies appear to move through the sky. Through a small circular window, the reader can watch the visible shape of the Moon change as the discs turn.

Operating the Interactive Lunar Volvelle

The digital lunar volvelle responds to simple circular gestures. Each disc can be rotated by holding near the part of the instrument it represents.

1. Moon disc: hold near the centre of the volvelle and turn to rotate the Moon Disc.
2. Sun disc: hold near the Sun pointer and turn to rotate the Sun Disc.
3. Calendar disc: hold near the dates/months on the outer ring and turn to rotate the calendar.

Each disc turns smoothly around the centre. By rotating and re-aligning them, the changing relationships between calendar, Sun, and Moon become visible.

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Moon Phase Volvelle

This volvelle is based on a student project developed as a printable, physical instrument by NASA JPL, California Institute of Technology. A paper tool that could be cut, assembled, and turned by hand. The version presented here is a redesigned digital simulation of that same idea. While the materials have changed, the underlying logic remains the same: understanding the Moon’s phases through alignment, rotation, and observation. The volvelle connects three ideas on a single circular surface: the calendar date, the Moon’s phase, and where to look in the sky.

Operating the Interactive Moon Phase Volvelle

The digital moon phase volvelle responds to simple circular gestures. Each disc can be rotated by holding near the part of the instrument it represents.

1. Moon Phase disc: hold near the Moon pointer and turn to rotate.
2. Calendar disc: hold near the dates/months on the outer ring and turn to rotate the calendar.

Each disc turns smoothly around the centre. By rotating and re-aligning them, the instrument makes visible how the Moon’s appearance, its position, and the time of day relate to one another.

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