Quadrivium Miscellany with Rithmomachia

The Cylinder Dial

A simple and small timekeeping instrument for travelers is constructed, which is shaped in the form of a smooth pole or cylinder of uniform thickness. It has a sciotherum original: "schioterū"; a Greek-derived term for a shadow-caster or gnomon. fixed perpendicularly and suspended at the top, which is capable of being rotated around. This Astronomy instrument is marked with lines on its side for each of the twelve signs [of the zodiac], so that through its rotation, its shadow may reach certain points to determine the hours throughout the months. I shall attempt to describe its measurement as clearly as I can, according to the principles of the astrolabe A sophisticated handheld model of the universe used for mapping stars and telling time; the author is using its complex geometry to simplify this smaller device. which I was able to discover.

Therefore, I first divide its circumference into six intervals by drawing lines from the top downwards. I label these with the six signs in which the days increase: namely, Capricorn, Aquarius, Pisces, Aries, Taurus, and Gemini. And then, returning, I pair the remaining six signs of the decreasing days with those that are equal to them in the length of their days: namely, joining Cancer with Gemini, Leo with Taurus, Virgo with Aries, Libra with Pisces, Scorpio with Aquarius, and Sagittarius with Capricorn. This pairing reflects the solar cycle; for example, the sun is at the same height during Aries (the spring equinox) as it is during Virgo (the autumn equinox), so they share the same markings on the dial. Then, those [lines] which are in the middle of each of the signs...