The view of the heavens must, at all times, have fixed the attention of mankind, and particularly so in those climates which were more propitious to observation, and whose temperature would naturally invite the philosopher, the lover of true knowledge, to contemplate the stars, and mark their motions and periodical

returns.

The great mass of the people were greatly interested in the progress of this knowledge; for agriculture required that the seasons should be distinguished, and their returns known. It would soon be discovered that the heliacal rising and setting of the stars, that is, when they are lost in the Sun's rays, and when they disengage themselves from his light, might answer this purpose. Hence, this species of observations may be traced back to such early times, that their origin is lost. Rude remarks, however, on the rising and setting of the stars, could not constitute a science; and astronomy cannot be said to have commenced, till observations being registered and compared, and the celestial motions examined with greater care, some attempt was made to explain their motions and their laws.

The apparent motion of the Sun, supposed, at first, to be a real motion, in an orbit inclined to the equator; the motion of the Moon, its phases and eclipses; the knowledge of the planets and their revolutions, and the sphericity of the Earth, were probably the chief objects of this antient astronomy; but the few monuments that remain of it are insufficient to ascertain either its epoch or its extent. We judge of its antiquity by the astronomical periods which it has transmitted to us; by some just and accurate notions which the Egyptians and Chaldeans seem to have had of the system of the world; and by the exact relation of the antient measures to the circumference of the Earth.

It appears that the practical astronomy of the early ages was confined to observations of eclipses, the rising and setting of the principal stars, with their occultations by the Moon and planets. The path, or apparent

motion, of the Sun was followed by means of the stars that were eclipsed by that body. The motion of the planets was determined by the stars which they came nearest to in their course. To distinguish these bodies, and recognise their motions, the heavens were feigned to be divided into constellations: and that zone, from which the Sun, or rather the Earth, the Moon, and Planets, were never seen to deviate, was called the Zodiac. It was divided into twelve constellations, viz. Aries, the ram; Taurus, the bull; Gemini, the twins; Cancer, the crab; Leo, the lion; Virgo, the virgin; Libra, the balance; Scorpio, the scorpion; Sagittarius, the archer; Capricornus, the goat; Aquarius, the water-bearer; and Pisces, the fishes. These were called signs, because they served to distinguish the Thus, the entrance of the Sun into Aries, in the time of Hipparchus, marked the commencement of the spring; after which it described the other signs, Taurus, Gemini, &c.; but the retrograde motion of the equinoxes changed the coincidence of the seasons; nevertheless, observers accustomed to mark the commencement of the spring, by the entrance of the Sun into the sign of Aries, have continued to mark this in the same manner, and have distinguished the signs of the zodiac from the constellations; the first being ideal, and serving only to designate the course of the Sun in the ecliptic. Now, indeed, we no longer use the signs of the zodiac, but mark the positions of the heavenly bodies on the ecliptic, according to their distance from the equinoctial point.

geasons.

M. La Place thinks that some of the names given to the constellations of the zodiac, appear to relate to the apparent motion of the Sun. Cancer, for example, seems to indicate the retrogradation of this body from the solstice; and the Balance denotes the equality of day and night. Other names may refer to the climate and agriculture of those nations to whom the zodiac owes its origin.

The most antient observations that have been trans

mitted to us, with sufficient detail, are, three eclipses of the Moon observed at Babylon, in the years 719 and 720 before the Christian æra, which Ptolemy not only cited, but employed in his determination of the motion of the Moon. [See p. 29, Time's Telescope, 1815, in which is given an account of the Astronomy of the antient Chaldeans.]

Astronomy is not less antient in Egypt than in Chaldea. The Egyptians were acquainted, long before the Christian æra, with the excess of the year, of one quarter of a day beyond 365 days: on this knowledge they formed the period of 1460 years, which, according to them, brought back the same seasons, months, and festivals of their years, the length of which was 365 days. The exact direction of the sides of their pyramids with the four cardinal points, gives a very advantageous idea of their accuracy. It is probable that they were in possession of methods of calculating eclipses: but what reflects most honour to their astronomy, was the sagacious and important observation of the motion of Mercury and Venus about the Sun. The reputation of their priests attracted to them the greatest philosophers of Greece; and it is eventhought that the school of Pythagoras is indebted to them for the sound notions which they professed, relative to the system of the universe. Among these people, astronomy was only cultivated in their temples, and by priests, who made no other use of their knowledge, than to consolidate the empire of superstition, of which they were the ministers. They disguised it under emblems, which presented to credulous ignorance heroes and gods, whose actions were only allegories of celestial phenomena, and of the operations of nature; allegories which the power of imita tion, one of the chief springs of the moral world, has perpetuated to our own days, and which have been mingled with our religious institutions. The better to enslave the people, they profited by their natural desire of penetrating into futurity, and created astroB

logy, persuading them that the stars influenced the events of life, and were able to prognosticate future destinies. This error seems to have been coeval with astronomy. In Persia, and in India, the commencement of astronomy is lost in the darkness which envelopes the origin of these people; but in no country do the people go so far as in China, by an incontestible series of historical monuments. The prediction of eclipses, and the regulation of the calendar, have always been regarded as important objects, for which public institutions have been established; but the scrupulous attachment of the Chinese for their antient customs, has contributed to keep this science in a perpetual state of infancy.

The Indian tables indicate a more refined astronomy; but M. La Place contends that it is not of a very remote antiquity. These tables have two principal epochs, which go back, one to the year 3102, the other to the year 1491 before the Christian æra. These epochs are connected with the mean motions of the Sun, Moon, and Planets; but La Place does not admit that the epochs to which they refer were established on observation. Nevertheless, the antient reputation of the Indians does not admit a doubt but that they have always cultivated astronomy; and the remarkable exactness of the mean motions which they have assigned to the Sun and Moon, necessarily required very antient observations. (See History for March.)

The Greeks were the disciples of the Egyptians, and of course they did not begin to cultivate astronomical knowledge till a long time after their masters. They also divided the heavens into constellations about fourteen centuries before the Christian æra. Their schools for philosophy did not produce a single observer before the foundation of the Alexandrine school. They treated astronomy as a science purely speculative, indulging in the most frivolous conjectures. Nevertheless, some sound ideas may be traced among them, which their astronomers collected in their travels, and afterwards improved. Thales, born

at Miletus, six centuries and a half before the Christian æra, went to Egypt for instruction, and, on his return to Greece, founded the Ionian school, and there taught that the earth was not an extended plane, but of a spherical shape: he also taught the obliquity of the ecliptic, and explained the true causes of the solar and lunar eclipses, and even went so far as to predict

them.

Thales had for his successors Anaximander, Anaximenes, and Anaxagoras: to the first is attributed the invention of the gnomon and geographical charts. Anaxagoras was persecuted by the Athenians, for having taught the truth in the Ionian school. They reproached him with having destroyed the influence of the gods on nature, by endeavouring to reduce the phenomena to immutable laws. He was, with his children, proscribed; and he owed his life to the protection of Pericles, his disciple and friend, who succeeded in procuring a mitigation of his sentence from death to banishment. From the Ionian school arose. the chief of one still more celebrated, Pythagoras, born at Samos, five hundred years before Christ, who had been the disciple of Thales. This philosopher advised him to travel into Egypt, where he consented to be initiated into the mysteries of the priests, that he might obtain a knowledge of all their doctrines. On his return to his native country, the despotism under which it groaned obliged him to quit it, and he retired to Italy, where he founded his school. What principally distinguished the Pythagorean school was, the knowledge of the two motions of the Earth, viz. that on its own imaginary axis, and that of its annual journey round the Sun.

According to the Pythagoreans, not only the planets, but the comets likewise, are solid bodies, in perpetual motion about the central body. These opinions, so perfectly correct, on the system of the universe, have been admitted and inculcated by Seneca, with the enthusiasm which a great idea, on so grand a subject, naturally excited in the soul of a philosopher.