This diagram, titled “Diagram about thunder, storms, rainstorms, and earthquakes,” seems to be a type of wind diagram, which arranged the terrestrial elements, planetary aspects, meteorological phenomena, and winds, signs of the zodiac, and the cardinal directions. Starting from the center we see the four elements—earth, water, air, fire—surrounded by the common planetary aspects. The first square is labeled παναχῆ, “everywhere,” then meteorological phenomena, e.g., lightning, thunder, earthquakes, hail, storms, then the 12 winds, then the signs of the zodiac. The very top of the diagram is labeled “south pole;” the bottom is labeled “north pole.” In red across the top half (starting at the 9 o’clock position) is “From the right (δεξιων) parts of the cosmos;” across the bottom half (starting at the 3 o’clock position) is “From the left parts of the cosmos.”
These diagrams have received little attention, which has (predictably) focused on the Latin tradition. Such diagrams appear regularly in Byzantine astronomical manuscripts.
This diagram is part of a collection of astronomical/cosmological diagrams in Royal MS 16 C XII, a later 16th-century manuscript first owned by Isaac Casaubon, the brilliant classical scholar and historian. Other texts in the codex include the trio of texts on the astrolabe—Philoponus’, Ammonius’, and Gregoras’—as well as a printed text on the astrolabe by Nikolaus Sophianos.