The Book of Experiments and Geomancy

The following transcription represents the numerical values found on the concentric rings of the volvelle volvelle: a rotating paper wheel used in medieval books to calculate dates, tides, or the positions of stars diagram.

Volvelle Numerals

Large Dial (Outer Movable Ring - Arabic Numerals):
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
These thirty divisions likely represent the days of the lunar month.

Large Dial (Middle Stationary Ring - Roman Numerals):
I II III IIII V VI VII VIII VIIII X XI XII
The use of "IIII" and "VIIII" is typical of medieval Roman numeral notation before the subtractive "IV" and "IX" became standardized.

Large Dial (Inner Ring - Roman Numerals):
I II III IIII V VI VII VIII IX X XI XII

Technical vocabulary: volvelle (rotating wheel), compotus original: "compotus" - the science of calculating the calendar, clock original: "horologium", lunar calendar, medieval astronomy