SPHÆRÆ IOAN.

6 Or because their horizon intersects the equinoctial and is intersected by the same at right spherical angles. Those, however, are said to have an sphaera obliqua oblique sphere who dwell on this side of the equinoctial or beyond. For them, one of the poles is always elevated above the horizon, while the other is always depressed.
7 Or because their artificial horizon intersects the equinoctial and is intersected by the same at unequal and oblique angles.

Two circular diagrams represent celestial configurations. The left diagram shows a sphere with a horizontal diameter labeled "ORIZON RECTA" Right Horizon and a vertical radius labeled "AEQVI" Equinoctial. The right diagram shows a sphere with a horizontal diameter labeled "ORIZON OBLI" Oblique Horizon, and two intersecting diagonal lines labeled "AEQVI" and "AXIS". In both diagrams, the lower half of the circle is shaded dark.

CONCERNING THE PARTS OF THE WORLD,

and what its parts are.

The mechanism of the universal world is divided into two parts: namely, the ethereal region and the elemental region. The elemental region, being prone to continuous alteration, is divided into four parts. For the earth is situated in the middle of all things as the center of the world: around it is water, around the water is air, and around the air is fire, there pure and not turbid, reaching the sphere of the Moon, as Aristotle says in his book of Meteororum Meteorology. Thus