BİRİNCİ FEN · İKİNCİ BÂB · SEKİZİNCİ FASIL · Beşinci Madde
Article Five
[51/b] Concerning Mercury’s first solstice and equinox, and the nodes of ascent and descent, regarding their positions on the zodiacal sphere; its own nature, characteristics, distance and span of its sphere, and the quantity of its mass.
O esteemed one! Know that astronomers have stated: The solstitial point of Mercury lies between its ascending and descending nodes. That is to say, it emerges from the inclined spherical surface of the zodiacal sphere in excess of its northern inclination, appearing ninety degrees after the node of ascent. For the points of the ascending and descending nodes move with the movements of the common-center sphere that corresponds to the movement of the zodiacal sphere. The position of Mercury’s first solstice on the zodiacal sphere was at twenty-six and a half degrees in the sign of Libra during the [Ghāṣir] year of the Rūmī chronology. Its equinox was likewise at twenty-six and a half degrees in the sign of Aries. The ascending node and its nodal point were, at that time, at twenty-six and a half degrees in the sign of Capricorn. And the descending node and the spring equinox (nevbahar) were at twenty-six and a half degrees in the sign of Cancer. Thus, it is understood that the points of Mercury’s solstice, equinox, ascending node, and descending node – as explained in the preceding paragraphs – have moved approximately eight degrees further from their locations during the [Ghāṣir] year. For the Rūmī chronology is now two thousand sixty-nine, and the Hijrī chronology is one thousand one hundred seventy.
Concerning Mercury’s nature and characteristics, astrologers agree: Mercury's nature, when singular, is balanced in coldness and dryness, possessing a masculine nature and being attributed to daytime. Due to its congruence with the nature of the star it conjoins, it is named “congruent” and "hypocrite." The attributes of Mercury are eloquence, alertness/intelligence, understanding, insight, mental clarity, acumen, speech, rhetoric, ornamentation, writing, calculation, accuracy, cleverness and attention, subtlety and skill in artistry, cunning and treachery.
It has been observed that if this star is destined to fall into the womb of a mother, the aforementioned attributes manifest in the child born. It has been ascertained that Mercury governs Sunday night and Wednesday. The first hours of that night and day are attributed to this star.
Concerning the quantity and mass of Mercury and its sphere’s distance, observers, geometers, and mathematicians unanimously state: The distance from the outer convex surface of Mercury's common-center sphere to the center of the world is calculated to be approximately two hundred seventy-six thousand six hundred fifty-two (276,652) leagues. The distance from its concave surface is calculated to be approximately eighty-seven thousand five hundred twenty-four (87,524) leagues. As for the thickness of this sphere, it is found to be approximately one hundred eighty-nine thousand six hundred twenty-eight (189,628) leagues. It has been proven with various evidence that Mercury’s mass is roughly one-thirtieth of Earth's. And it is known with certainty by the learned scholars that the aforementioned size and distance are as described. Praise be to us that the Merciful One, who fulfills all our needs, has appointed Mercury, the scribe of the heavens.
“He who encompasses everything in [His] knowledge, creates and innovates with His wisdom; the Eternal, Powerful and Mighty is God, the Exalted is His glory.”
[504]. Director: The sphere that carries the center of the epicycle, posited to explain the apparent growth of the diameter of Mercury’s epicycle at +/- 120 degrees.
[505]. Nisf-i nehar: Meaning both meridian and midday.
[506]. The phrase "mustaqīmu'l-hareke" in the manuscript is erroneously written as “batīu’l-hareke.”
Mercury’s director sphere and its carrying sphere are described, along with their structure and movements.
Like Mercury itself, the star is a solid, luminous, spherical body enclosed by a single surface. It is situated on the body of the epicycle in such a manner that one of its poles lies near the belt, on one side, touching the surface of the epicycle at a common point. That is to say, the body of the star has entirely been included within the body of the epicycle. The carrying sphere, however, is observed to rotate with Mercury’s epicycle and around its own center, like the rotation of the epicycle, in accordance with the rising of the signs. Observers have verified this through observation of solar eclipses (kusūf) occurring at midday (nisf-i nehar).
When the star is located on the upper part of the epicycle, it appears to move swiftly as its own center’s movement corresponds to the movement of the epicycle's center in accordance with the rising of the signs. If it is inclined somewhat toward the epicycle, it appears to move straightly. When descending into the lower portion of the epicycle and situated at its midpoint, it appears to move slowly. For the star’s own center being in descent, its movement is not visible, but only the movement of the epicycle's center is seen. And when the star approaches the lowest part of the epicycle…
Here's the translation, aiming for faithfulness and preserving meaning as requested:
When the conjunction of the fixed stars occurs in a sign of the Zodiac, it is born with the Burçlar. The motion of the taşıyıcı küre (carrier sphere) corresponds to the birth of the Burçlar, and the two motions are contrary and opposing, appearing as if they were stationary stars.
Finally, when the star descends to the lowest point of the Episikl felek (epicycle), its own movement exceeds that of the center of the epicycle and appears to be turning back. Once the return of the star is complete and the two movements equalize, it seems to stop a second time. Then it stops again, and then appears to move slowly. For at this time, the center of the star’s own sphere is moving beyond the visible horizon of the epicycle, so only the movement of the center of the epicycle is seen.
After slowing down, it moves straight again, then accelerates. Meanwhile, the star completes its revolution within its own epicycle in an orderly fashion. For all spheres and those contained within them move with respect to their equatorial belts in a simple, similar, and linear manner. The first station is called the first *makãm* (stage) from the star’s return to its previous stationary point, and the subsequent one the second *makãm*.
Mercury's period of retrogradation is twenty-one days; its duration in direct motion is three months and five days. When this star is inclined three and four-ninths degrees north and south with respect to the zodiacal belt of its taşıyıcı felek (carrier sphere), and when its epicycle has a declination, both northwards and southwards from its visible apogee and perigee, differing by approximately six degrees in latitude, it continues its movements in this manner, appearing unstable in its course, and is named "hesitant" (*mütehayyir*).