Such, nearly, is the description given by Aratus of the celestial sphere; and the constellations are, in general, the same as those which are represented on the modern globes. Some inconsistencies which exist in it were pointed out by Hipparchus, who lived about 100 years before Christ, and wrote a commentary on the poem. It is plain that the descriptions have been compiled from observations made by persons at different places, and probably in different ages; for in ono part of the work it is stated that the extremity of Draco, and in another the girdle of Cepheus, touches the horizon, while in a third place Bootee is said to go below that circle, except his hand : and these circumstances are quite incompatible with observations made in the same latitude. It should be remarked that, in the Greek ephero, the stars are not always placed in the seine parts of the figures as they occupy at present: thus the principal star of Aries is placed by Hipparchus in the front foot of the animal, while on the modern globes it is placed in the head.
It would be desirable to ascertain from the poem of Aratus the position of the equinoctial or solaticial points, in order to find the epoch of the observations on which the description is founded, but it is to be regretted that nothing satisfactory can be discovered concerning the subject. It is stated in the poem that the southern tropic cuts the middle of Capricornus, and hence the equinoethal colure should pass through the middle of Aries. Now, in the presumed age of Eudoxus, the first remarkable star 7 in Aries was nearly at the point in which the trace of the ecliptic in the heavens cuts that of the equator ; and if wo suppose the extent of the constellation to be 30 degrees, the middle point, reckoning from that star, would bo nearly at the 15th degree of longitude. The longitude of that star is now about 30°, and hence the equinoctial colure would have retrograded as much as 45 degrees, which at the known rate of the precession would take place in about 3200 years: consequently the epoch would be about the year 1400 D.C. Or, if with Ptolemy it is supposed that the extent of the constellation between the first star 7 of Aries and the first star of Taurus (now 8 Arietis) is only 18 degrees, the middle point would be in the 9th degree of longitude, and the retrogradation would be 39 degrees, which would place the epoch about the year 970 n.e. Nothing, however, can be more uncertain than conclusions drawn from such data.
The taste for ornamenting buildings with sculptures representing astronomical subjects appears to have existed in ancient Rome, as well as in Egypt and in the Fast; for in 1708 a fragment of a pLanispliere was discovered in that city. It has in its centre a serpent, probably an emblem of time, and near it two animals, apparently bears ; about the serpent are the remains of three concentric rings, divided into compart ments containing figures, among which are some of the zodiacal constellations.
That the Romans adopted the Greek sphere is evident from the descriptions of the constellations in the Astronomicon ' of Maniliue: those of the zodiac, in particular, are given in the verses "Aurato princeps erica in yellers: fulgens," &c.; and the poem contains a detailed
account of their astrological dispositions and qualities. The twelve signs are divided into masculine and feminine alternately, and are appropriated to different deities. There is also a division of the zodiac I into twelve parts, which are designated Athla, or labours, and relate to the occupations or professions of men (lib. iii., v. 93). Four constella tions, comprehending a space equal to one-third of the circumference of the zodiac, are said to constitute a trigon ; three a tetragon, and so on ; and there are four trigons arising from the different constellations, which may coincide with the angles of an equilateral triangle supposed to be inscribed in the zodiac : the like is to be understood with respect to the tetragon, hexagon, &e. Each sign of the zodiac is supposed, in the poem, to give a certain number of years to the life of a man ; and his profession or fortune is imagined to depend on the particular sign which is rising at his birth, according to the qualities or uses of the animal by which the sign is distinguished (lib. iv., v. 122). It is also asserted that the characters of men depend on the qualities of the extra-zodiacal constellations : thus, persons born when the ship Argo rises are said to become seamen or to have an interest in naval affairs (lib. v., v. 39).
Scaliger, in his notes on Maniliue, bas given, from a manuscript of Aben-Ezra, a description of three planispheres, of which one is sup posed to have related to the astronomy of the ancient Persians, and another to that of the 'Hindus ; the third is supposed to be either Egyptian or Greek. The significations of the figures in the Persian sphere are very uncertain ; but among those which have been recog nised are Urea Major and Ursa Minor, and a winged horse, besides Virgo, Leo, and Taurus. The figures of men and women are without designations ; but among the former is one on a throne, which is thought to represent Cepheus, and one in a kneeling posture, which may be Hercules ; of the latter, there is one which is presumed to represent Cassiopeia or Andromeda. A figure of a ship is also distin guished. It is asserted in the Zend-Avesta' [Zsan-Avssre] that the ancient Persians divided the zodiac into twenty-eight constellations, or houses of the moon, and also into twelve signs : to these last are assigned names which correspond to those at present given to the con stellations in that region of the heavens; and the cluster called the Hyades (in Taurus) is described as a bull with gilt horns. The division of the zodiac into twenty-eight lunar mansions prevailed also among the Arabian astronomers in or before the 9th century. It is mentioned by Alfragan, who states (' Elementa Astron.,' Al). 850) that the first was called Xartan, and that it commenced near the three principal stars in Aries.