Quadrivium Miscellany with Rithmomachia

I observe what rises in the aforementioned formula. And however much space the number of those degrees occupies on this line, measuring downward from the starting point original: a coransto; likely referring to the vertex or the top "crown" of the scale mentioned on the previous page, I measure out just as much space in the length of the instrument itself, downward from the sciotherum original: sciothero; from the Greek for "shadow-catcher," referring to the gnomon or the base of the shadow-casting pin. Looking at the line which is assigned to each zodiac sign or month, I establish the boundary for each hour.

For example: at the beginning of Capricorn The sign associated with the winter solstice, when the sun is at its lowest noon altitude, at the end of the sixth hour In the system of "unequal hours," the sixth hour always represents midday or noon, the sun sun (sol) rises to eighteen degrees. Therefore, however much space is contained in the often-mentioned line from the starting point down to the end of the eighteenth degree, I establish exactly that much on the line that governs the order of Capricorn, marking it as the boundary for the sixth hour.

And by finding the certain number for each hour of each of the signs and months, I mark the points. Finally, by drawing oblique lines from point to point above the end of each hour—as the increases and decreases of the days require—I shall complete the measurement of this entire horologium original: horologii; a general term for a time-keeping device, in this context a sundial or solar quadrant.