It is a Pole sith in the constellations of Heaven, we call Poles, the two ends or extremities of them, and in the constellations of the Zodiack, we call the first Pole that which is next to the Equator, and the second Pole that which stretcheth towards the North, or towards the South in the Eccliptical Line.
In this sense, the first Pole of the Sign of Aries, is that which hath its first degree in the Equator; the second is, that which stretcheth towards the North in the Eccliptick, and this last Pole is called Bastarnan, because it is Vertical to Bastarnia, as the Astrologers set down their Climates, Kingdoms, Provinces and Towns under the twelve Signs.
Fourthly, We must suppose that this word to double, may signifie three things. 1. In Sea-mens tearms; it signifieth to go beyond some place, as to double the Cape of bona Speranza, which is called in Italian, Tramontare; that is, to go beyond. 2. It signifieth to do twice the same thing, as Jacob did double his service for Rachel, &c. 3. In matter of traveling; it signifieth to go twice as far as is requisite.
To double, in this place cannot be understood in the first sense; because the constellations never stretcht out of their compasses, though the Stars of which they are compounded, have their peculiar motions.
To understand this, we must know that the Stars of the Firmament have their peculiar motions from West to East, upon the Pole of the Eccliptick, and that they go that way a matter of one Degree, in the space of about 100 years, and consequently the Stars do retrograde every year in the Eccliptick from West to East 52 Seconds. Ptolomeus holdeth this opinion, but other renowned Astrologers give them more: For my part I am of Tychobrahe’s opinion, who allowed them one Degree of retrogradation in 70 years and 7 Months, and consequently 51 Seconds every year.
According to this Doctrine the Star that is in the Horn of Aries, was observed by Tymocharis in 2d Degree; 150 years after, Hipparchus observed it in the first; 265 years after, Ptolomeus saw it in the 6 Degree; 740 years after, Albathognius observed it in the 18 Degree; 304 years after, Alphonsus King of Spain, found it in the 6 Degree; 265 years after, Copernicus did observe it to be in the 27 Degree and two Minutes; 61 years after, Tychobrahe saw it in the 27 Degree, and above 37 Minutes; so that in the space of 61 years it had gone 35 Minutes.
By this Doctrine we see that the whole constellations do not go beyond their Poles, though the Stars that Compound them change their Poles every year of 51 Seconds.
To double, then here cannot be taken in the first sense, nor in the third sense, for the first reason, it must then be in the second sense; and thus Aries doubleth his Bastarnan Pole; that is, Aries maketh twice his Pole, which answereth to Bastarnia.
If you ask how it cometh to pass that Aries doubleth this Pole, and in what place of Heaven we set this Bastarnan Pole. I answer to the first, that Aries doubleth his Pole, when one of those 13 Stars cometh to that point, which is a Northern or Western Pole to that sign in the Eccliptick. As to the second: I answer, that the place ought to be its last Degree, viz. the end of the 30 Degree.