SECOND STATEMENT.

To understand the motions of the eighth, ninth, and tenth spheres, and to truly visualize the Zodiac according to which all the following instruments are regulated.

Motion of the Ninth and Tenth spheres.

There would be no need for an explanation of the Tenth, Ninth, and Eighth spheres here, since the purpose of this work is nothing other than to teach how celestial motions are investigated without any deep theoretical speculation. However, a certain controversy occasionally arises concerning the beginning of the Ecliptic The apparent path of the Sun across the sky. (which is distributed into twelve signs), and whether it ought to be placed in the eighth, ninth, or tenth sphere. Furthermore, since frequent mention is made throughout this book of this line and of the twelve signs, I could not allow myself to skip discussing this doubt right from the beginning. It is hidden from no one that beyond the orbits of the seven "wandering stars" The planets: Moon, Mercury, Venus, Sun, Mars, Jupiter, and Saturn., three more remain: namely the eighth, in which the fixed stars reside; then the Ninth; and the Tenth, which is the last. The tenth sphere is carried from the east to the west in 24 hours, as we learn daily by our eyes. For we see how the Sun and the remaining stars (which the sphere sweeps along with itself most violently) rise and set. The ninth sphere is driven from west to east through the highest part of the heaven, contrary to the tenth, and—speaking naturally—completes its course in 49,000 years. In the middle of this course, we will imagine the ecliptic, marked below with the letters C, A, E, and M. The beginning of Aries is A, around which must be understood a circle that encompasses nine degrees in its radius, and which is divided into twelve signs, just like another circle or Epicycle A small circle whose center moves around the circumference of a larger one.. The signs in it are noted by numbers from B toward C, because B is the "head" of this small cycle, declining toward the North. In the same way, imagine a small circle described opposite the letter A, where you place the beginning of Libra. In this ecliptic of the ninth sphere, you may place the twelve signs if you wish, though they are of no use except for the starting point of Aries, which the letter A represents. Understand that the eighth sphere lies beneath this ninth sphere. An ecliptic likewise occupies its middle, in which you will place a point (such as point H expressed in the following figure), which we will also call the beginning of Aries, but of the eighth sphere. The motion of this sphere is nothing else than its rotation with point H in the smaller circle, following the succession of the signs—that is, from B toward C—completing its course through D and E and back again
The Motion of Trepidation.

into B in a span of 7,000 years; and that is called the motion of trepidation A historical theory that the equinoxes "shook" or oscillated back and forth rather than moving in a continuous circle.. In this way, you shall also establish the diametrically opposite point H, which you will call the beginning of Libra—specifically of the eighth sphere—moving equally with the beginning of Libra of the ninth sphere. And although...

Where the ecliptic, according to which the judgments of both astronomers and astrologers proceed, is to be established.

And although point H is called the beginning of Aries, the remaining signs of the Zodiac are not to be understood as being there; therefore, visualize the Signifer The Zodiac, literally "the sign-bearer." correctly. First, imagine the Equinoctial The celestial equator. equidistant from both poles, its surface dividing the entire machine of the world. After this, imagine the surface of the ecliptic of the eighth sphere reaching the same place, namely to the tenth heaven. And there, finally, the true ecliptic is shown. In the place where the Equinoctial intersects with the ecliptic, that is the beginning of the Ecliptic and the first point of Aries. Call this line, together with the twelve signs, the "True" one; for according to it, all the following instruments must be understood. The intersection of the Zodiac and the equator represents the point of the true equinox, which as soon as the Sun enters it, the Equinox is created for the whole world. It should be known, however, that this point does not always stay in the same place, but is repeatedly changed here and there on the equator, just as happens in an epicycle for a point designating the mean apogee The point in an orbit farthest from the Earth.. For this reason, the equinoxes
Why the equinoxes are perpetually varying.

perpetually vary and "anticipate" The phenomenon of the precession of the equinoxes.. For in the time of Christ, the vernal equinox occurred on the 24th day of March in a Bissextile [leap] year, or the 25th day of March in a common year. In our age, it happens on the 11th of March in common years, or the 10th in intercalary years—if indeed we do not withdraw our faith from the calculations of the tables. This is likewise attested by the observation of the shadow of the solar rays, which is simple and open; it can be experienced without any instruments on any surface, whether horizontal, vertical, inclined, or declined. For at the time of the equinox, the tip of a style The pointer or gnomon of a sundial. marks a perfectly straight shadow line throughout the day, which at all other times
Investigation of the equinox by solar rays.

is always described by the shadow as oblique or curved. Since the investigation of the equinox is so easy and ready, who would not wonder that some were so foolish that, when they attempted to "cleanse" the Roman Calendar, they dared to transfer the equinox to the 5th of March? They thought they were amending it, when in fact they were making the imperfection five full days greater than it was before. Therefore, that you may more truly understand the motion of the eighth sphere and the point of the equinox, an example is needed. At the time the greatest Emperors CHARLES and FERDINAND Charles V and his brother Ferdinand I, Apian's patrons. were born, the mean motion of the eighth
Motion of the Ninth and eighth spheres at the time of CHARLES and FERDINAND.

sphere was nearly 0 signs, 11 degrees, 1 minute, and 40 seconds. This same motion was also the beginning of Aries of the ninth sphere, from the birth of Christ until under the tenth. The beginning of Aries of the eighth sphere, from the northern point B (the start of the small circle) to the letter H, is an arc of the eighth sphere called the Argument. From this, it is clear that at the birth of the Emperors, the Ecliptic of the eighth sphere was of such a kind that it moved through H, K, F, and M. The arc from F to K was the mean motion, while from K to H was the equation A correction factor used to find the true position from the mean position., which was 8 degrees and 45 minutes. Already the apogees have moved forward from Christ the Savior to the times of the Emperors. Now, if you imagine a line produced from the center of the world through the intersection
The beginning of the tenth sphere.

of the ecliptic of the eighth and the equinoctial (which is point F), then that line will show the beginning of Aries in the tenth sphere, at the letter G; and G is the point of the equinox. And having tasted these things beforehand, it suffices for now.