History. ASTRONOMY, from astron or astron, a star, and nomos, a law, is the science which treats of the laws observed by the stars in their motions. By an extension of signification, it embraces every thing that is known relating to the nature and constitution, as well as to the motions, of the celestial bodies.
The present treatise is divided into Four Parts. In the First, which contains the HISTORY OF ASTRONOMY, the progressive advancement of the science from the times of the Chaldeans and Egyptians to the present day is briefly sketched, and the labours of those illustrious indi-
viduals commemorated, who have either theoretically or practically contributed most to its progress. The Second Part, which we have denominated THEORETICAL ASTRONOMY, is devoted to a general view of the science,—to the explanation of the different theories and methods by which the motions of the celestial bodies are represented, and their places computed; and the description of such facts as observation has made known respecting their nature and constitution. Part Third treats of PHYSICAL ASTRONOMY; and Part Fourth of PRACTICAL ASTRONOMY.
Astronomy, if we dignify by that name the first rude attempts that were made to discover the order and connection of the celestial motions, may probably be regarded as the most ancient of all the sciences. In fact, a certain degree of attention to the heavenly bodies is forced even on the savage who inhabits the forest, and derives his subsistence from the spontaneous productions of the earth. The regular vicissitude of day and night inevitably compels him to observe the diurnal course of the sun; and he cannot fail soon to perceive, that the variety and succession of the seasons is equally dependent on the oblique annual course of the same great luminary. The moon, too, in the absence of the sun, is an object so conspicuous, so consoling, and so useful, that her motions must at all times have been watched with attention and interest; while her various phases, her alternate waxings and wanings, her regular disappearance and return after equal intervals of time, would be contemplated with admiration and delight. Nor are the wonders of the starry firmament less calculated to strike even the most heedless observer of the heavens. The magnificent spectacle of the sky bespangled with brilliant points, and revolving in obedience to eternal and unalterable laws, affords a constant succession of new objects of sublime and exalted contemplation. The occasional recurrence, also, of eclipses and other unusual phenomena, which seem to interrupt the general order and uniformity of the celestial motions, would stimulate to attentive observation; for the vanity of man has in all ages rendered him eager to connect his own destiny with the heavens, while his timidity has prompted him to regard every apparent deviation from the ordinary course of events as an emblem of the wrath, and a precursor of the vengeance, of superior beings.
But though mankind were probably first impelled by motives of mere curiosity to observe the courses of the stars, no great length of time could elapse ere they perceived that the regular and uniform revolutions of the heavens might be rendered subservient to their own wants and conveniences. By the help of the stars the shepherd, during the night, could count the hours, the traveller track his course through the uniform wastes of the desert, and the mariner guide his bark over the ocean: the husbandman, also, learned to regulate his labours by the appearance of certain constellations, which gave him warning of the approaching seasons. The indications de-
rived from the simple observation of such phenomena were doubtless extremely vague; but as civilisation advanced, the necessity of determining accurately the length of the solar year and of the lunar month, in order to regulate the calendar and the religious festivals, led to the accumulation and comparison of different observations, whereby errors were gradually diminished, and the foundations laid of a more perfect acquaintance with the heavenly motions.
Astronomy, presenting so many objects of interesting curiosity, and having so many practical uses, could not fail to be one of the sciences first cultivated by mankind. Its origin is consequently hid amidst the obscurity and traditions of the remotest ages, and is in fact coeval with the origin of society, and the earliest development of the human intellect. The records or traditions of almost every ancient nation furnish some traces of attention to the state of the heavens, and of some rude attempts to discover the laws, the order, and the period of the most remarkable phenomena,—such as eclipses of the sun and moon, the motions of the planets, and the heliacal risings of the principal stars and constellations. The Chaldeans and Egyptians, Chinese and Indians, Gauls and Peruvians, equally regard themselves as the inventors of astronomy; an honour, however, of which Josephus deprives them all, in order to ascribe it to the antediluvian patriarchs. The fables relating to the two columns of brick and marble which these sages are said to have erected, and on which they engraved the elements of their astronomy, to preserve them from the universal destruction by fire and water to which, they are said to have learned from Adam, the earth was doomed, are not worth the trouble of repetition; nor is there any better proof than the assertion of that credulous historian, of their acquaintance with the annus magnus, or, as is most probably supposed, the astronomical cycle of 600 years, which brings back the sun and moon to the same points of the heavens so nearly, that its discovery implies a pretty correct knowledge of the solar and lunar motions. Passing over, therefore, those periods that present us only with a scanty detail of traditional observations or unimportant facts, we will proceed to give a brief account of the state of astronomy among some early nations who have undoubtedly contributed to the improvement of the science, or who, at least, have transmitted to future ages some monuments of their
History. astronomical labours, and of their attention to celestial observations.