BİRİNCİ FEN · İKİNCİ BÂB · ÜÇÜNCÜ FASIL · Üçüncü Madde
**Article Three**
Concerning the Epicycle of Saturn (Zuhal).
Know then, esteemed one, that astronomical scholars, in describing the states and orderliness of the celestial bodies, do not suffice with merely this; rather, they posit a second sphere, external to the center, around the Sun. However, regarding the other planets, they have demonstrated the existence of smaller spheres not encompassing the Earth (the *af’ak-i siġar*), naming them the “carrying spheres” (*af’ak-i tadawir; af’ak-i hamil*). Thus, the Epicycle of Zuhal is a small sphere, not encompassing the Earth, within its representative sphere, situated on a belt (mıntıqa) of a second, external sphere that carries it, and whose diameter is tangent to the two surfaces of that carrying sphere.
The Epicycle is a small sphere, parallel to the Earth’s plane in Zuhal's orbit, placed upon the trajectory of the aforementioned secondary, externally-centered sphere. [485] The Epicycle is a solid sphere enclosed by a single surface, and within its own space, it moves with a specific motion from west to east, along the sequence of the constellations, rotating together with Zuhal (Saturn), which remains fixed between its two poles. This Epicycle completes one rotation in a day, moving this star approximately one degree out of its three hundred sixty degrees of circumference around its own belt, thereby causing it to move towards the Sun’s midpoint, completing a full cycle annually – and this is what they call the variable motion of the star (*hareket-i ihtilaf-i kevkeb*).
Zuhal itself is a solid, spherical celestial body, enclosed by a surface, filled with light and brilliance. It is situated within its carrying sphere in such a way that the surface of the star touches the circumference of the carrying sphere at a common point. That is to say, the entirety of the star’s mass appears within the mass of the carrying sphere, touching its two poles. And just as the Epicycle moves along a specific sequence on one side of the carrying sphere, so too have most astronomers observed Zuhal itself rotating around its own center.
Thus, the condition of the planet Zuhal has been ascertained in this manner, and its parts, operation, order, and appearance have been explained and described to this extent. By comparison with this, the form, structure, and other conditions of the sphere of Müşteri (Jupiter) found within Zuhal’s void, and the sphere of Merih (Mars) contained therein, as well as the sphere of Zühre (Venus) found within the Sun's sphere, are known through their similarities to this Zuhal (Saturn). However, since these aforementioned spheres possess different attributes, distances, and masses relative to one another, it is necessary to state in a separate discourse each of their structures, the quantity of their movements, the qualities of their stars, and their distance and spherical constitution, along with their particular characteristics.