WHY THE SAME STARS APPEAR AT SOME TIMES MORE LOFTY AND AT OTHER TIMES MORE NEAR

Latine · Mayhoff 1906

igitur a terrae centro apsides altissimae sunt Saturno in scorpione, Iovi in virgine, Marti in leone, soli in geminis, Veneri in sagittario, Mercurio in capricorno, lunaein tauro, mediis omnium partibus, et e contrario ad terrae centrum humillimae atque proximae. sic fit ut tardius moveri videantur, cum altissimo ambitu feruntur, non quia adcelerent tardentve naturales motus, qui certi ac singuli sunt illis, sed quia deductas ab summa apside lineas coartari ad centrum necesse est, sicut in rotis radios, idemque motus alias maior, alias minor centri propinquitate sentitur. altera sublimitatium causa, quoniam a suo centro apsidas altissimas habent in aliis signis, Saturnus in librae parte vicesima, Iuppiter cancri quinta decima,Mars capricorni XXVIII, sol arietis XVIIII, Venus piscium XXVII, Mercurius virginis XV, luna tauri III. tertia altitudinum ratio caeli mensura, non circuli, intellegitur, subire eas aut descendere per profundum aëris oculis aestimantibus.

Huic conexa latitudinum signiferi obliquitatisque causa est. per hunc stellae quas diximus feruntur, nec aliud habitatur in terris quam quod illi subiacet, reliqua a polis squalent. Veneris tantum stella excedit eum binis partibus, quae causa intellegitur efficere ut quaedam animalia et in desertis mundi nascantur. luna quoque per totam latitudinem eius vagatur, sed omnino non excedens eum. ab his Mercurii stella laxissime, ut tamen e duodenis partibus—tot enim sunt latitudinis—non amplius octonas pererret, neque has aequaliter, sed duas in medio eius et supra quattuor, infra duas. sol deinde medio fertur inter duas partes flexuoso draconum meatu inaequalis, Martis stella quattuor mediis, lovis media et super eam duabus, Saturni duabus ut sol. haec erit latitudinum ratio ad austrum descendentium aut ad aquilonem subeuntium. hac constare et tertiam illam a terra subeuntium in caelum, et pariter scandi eam quoque existimavere plerique falso. qui ut coarguantur, aperienda est subtilitas inmensa et omnes eas conplexa causas.

Convenit stellas in occasu vespertino proximas esse terrae et altitudine et latitudine, exortusque matutinos in initio cuiusque fieri, stationes in mediis latitudinum articulis, quae vocant ecliptica. perinde confessum est motum augeri, quamdiu in vicino sint terrae; cum abscedant in altitudinem, minui. quae ratio lunae maxime sublimitatibus adprobatur. aeque non est dubium in exortibus matutinis etiamnum augeri atque a stationibus primis tris superiores deminuerese usque ad stationes secundas. quae cum ita sint, manifestum erit ab exortu matutino latitudines scandi, quoniam in eo primum habitu incipiat parcius adici motus, in stationibus vero primis et altitudinem subiri, quoniam tum primum incipiant detrahi numeri stellaeque retroire. cuius rei ratio privatim reddenda est. percussae in qua diximus parte et triangulo solis radio inhibentur rectum agere cursum et ignea vi levantur in sublime. hoc non protinus intellegi potest visu nostro, ideoque existimantur stare, unde et nomen accepit statio. progreditur deinde eiusdem radii violentia et retroire cogit vapore percussas. multo id magis in vespertino earum exortu, toto sole adverso cum in summas apsidas expelluntur minimaeque cernuntur, quoniam altissime absunt, et minimo feruntur motu, tanto minore, cum hoc in altissimis apsidum evenit signis. ab exortu vespertino latitudo descenditur parcius iam se minuente motu, non tamen ante stationes secundas augente, cum et altitudo descenditur, superveniente ab alio latere radio eademque vi rursus ad terras deprimente, qua sustulerat in caelum e priore triquetro. tantum interest, subeant radii an superveniant, multoque eadem magis in vespertino occasu accidunt. haec est superiorum stellarum ratio; difficilior reliquarum et a nullo ante nos reddita.

English · Bostock & Riley 1855–57

The apsides which are the highest from the centre of the earth are, for Saturn, when he is in Scorpio, for Jupiter in Virgo, for Mars in Leo, for the Sun in Gemini, for Venus in Sagittarius, and for Mercury in Capricorn, each of them in the middle of these signs; while in the opposite signs, they are the lowest and nearest to the centre of the earth. Hence it is that they appear to move more slowly when they are carried along the highest circuit; not that their actual motions are accelerated or retarded, these being fixed and determinate for each of them; but because it necessarily follows, that lines drawn from the highest apsis must approach nearer to each other at the centre, like the spokes of a wheel; and that the same motion seems to be at one time greater, and at another time less, according to the distance from the centre.

Another cause of the altitudes of the planets is, that their highest apsides, with relation to their own centres, are in different signs from those mentioned above. Saturn is in the 20th degree of Libra, Jupiter in the 15th of Cancer, Mars in the 28th of Capricorn, the Sun in the 19th of Aries, Venus in the 27th of Pisces, Mercury in the 15th of Virgo, and the Moon in the 3rd of Taurus.

The third cause of the altitude depends on the form of the heavens, not on that of the orbits; the stars appearing to the eye to mount up and to descend through the depth of the air. With this cause is connected that which depends on the latitude of the planets and the obliquity of the zodiac. It is through this belt that the stars which I have spoken of are carried, nor is there any part of the world habitable, except what lies under it; the remainder, which is at the poles, being in a wild desert state. The planet Venus alone exceeds it by 2 degrees, which we may suppose to be the cause why some animals are produced even in these desert regions of the earth. The moon also wanders the whole breadth of the zodiac, but never exceeds it. Next to these the planet Mercury moves through the greatest space; yet out of the 12 degrees (for there are so many degrees of latitude in the zodiac ), it does not pass through more than 8, nor does it go equally through these, 2 of them being in the middle of the zodiac, 4 in the upper part, and 2 in the lower part. Next to these the Sun is carried through the middle of the zodiac, winding unequally through the two parts of his tortuous circuit. The star Mars occupies the four middle degrees; Jupiter the middle degree and the two above it; Saturn, like the sun, occupies two. The above is an account of the latitudes as they descend to the south or ascend to the north. Hence it is plain that the generality of persons are mistaken in supposing the third cause of the apparent altitude to depend on the stars rising from the earth and climbing up the heavens. But to refute this opinion it is necessary to consider the subject with very great minuteness, and to embrace all the causes.

It is generally admitted, that the stars, at the time of their evening setting, are nearest to the earth, both with respect to latitude and altitude, that they are at the commencement of both at their morning risings, and that they become stationary at the middle points of their latitudes, what are called the ecliptics. It is, moreover, acknowledged, that their motion is increased when they are in the vicinity of the earth, and diminished when they are removed to a greater altitude; a point which is most clearly proved by the different altitudes of the moon. There is no doubt that it is also increased at the morning risings, and that the three superior planets are retarded, as they advance from the first station to the second. And since this is the case, it is evident, that the latitudes are increased from the time of their morning risings, since the motions afterwards appear to receive less addition; but they gain their altitude in the first station, since the rate of their motion then begins to diminish, and the stars to recede.

And the reason of this must be particularly set forth. When the planets are struck by the rays of the sun, in the situation which I have described, i. e. in their quadrature, they are prevented from holding on their straight forward course, and are raised on high by the force of the fire. This cannot be immediately perceived by the eye, and therefore they seem to be stationary, and hence the term station is derived. Afterwards the violence of the rays increases, and the vapour being beaten back forces them to recede.

This exists in a greater degree in their evening risings, the sun being then turned entirely from them, when they are drawn into the highest apsides; and they are then the least visible, since they are at their greatest altitude and are carried along with the least motion, as much less indeed as this takes place in the highest signs of the apsides. At the time of the evening rising the latitude decreases and becomes less as the motion is diminished, and it does not increase again until they arrive at the second station, when the altitude is also diminished; the sun’s rays then coming from the other side, the same force now therefore propels them towards the earth which before raised them into the heavens, from their former triangular aspect. So different is the effect whether the rays strike the planets from below or come to them from above. And all these circumstances produce much more effect when they occur in the evening setting. This is the doctrine of the superior planets; that of the others is more difficult, and has never been laid down by any one before me.