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INTRODUCTION.

The term ASTRONOMY, like most terms of science, is derived from the ancient Greek language. Astronomia, astronomy, is compounded of astron, a star or constellation, and nomos, a law, the law of the stars. It may be defined the science which treats of the heavenly bodies.

Astronomy is a science of great antiquity. Its early history has too many allegorical representations to admit of a satisfactory elucidation. It is, however, probable, that some scanty knowledge of this science must have been nearly coeval with the existence of man. The grandeur of the delightful canopy extended over his head, must have attracted the curiosity of the most careless and rude wanderer of the forest, much more of the attentive shepherd. Besides, the common concerns of life are in some measure regulated by a partial knowledge of astronomy.

Both the Chaldeans and Egyptians claimed a very high antiquity; and equally claimed the honor of being the first cultivators of astronomy. It may not be easy, at this late day, to determine which has the best founded claim. Most authors seem agreed in fixing the origin of this science either in Chaldea or Egypt. The shepherds, who " watched their flocks

by night,” on the beautiful plains of Babylon, or in the extended vale of the Nile, could not be careless spectators of the varying aspects of the heavens. The tower of Belus was the boast of the Chaldeans. This is thought by some to have been an astronomical observatory. They gloried in their astronomer, Zoroaster, placed by them 500 years before the destruction of Troy. The Egyptians, with equal ostentation, vaunted of their priests. The colleges of these they considered as the depositaries of every species of knowledge. In the monument of Osymandyas, it is said, there was a golden circle of 365 cubits in circumference, divided into 365 equal parts, according to the days of the year, with the heliacal rising and setting of the stars for each day. It is proper to state, that, whatever may be thought of the tower of Belus, or the circle of Osymandyas, both the Chaldeans and Egyptians were extremely well situated for astronomical observations, being almost always favored with a pure atmosphere, and a sky of delightful serenity. A very favorable opinion of the Egyptians must be formed from the position which they gave to their pyramids, the faces of these being accurately directed to the four cardinal points of the heavens.

Besides the Chaldeans and Egyptians, the Arabians may justly claim a high antiquity in astronomical knowledge. The land of Uz, famous for the afflictions of Job, was without doubt a district of Arabia. Authors are agreed, that the book of Job is very ancient-is unrivalled in antiquity, except, perhaps, by the books of Moses. From the familiar manner in which Arcturus, Orion, and Pleiades

are introduced in that book, it may be ascertained, that not only were names given to some of the stars, but constellations had been designated and named, so as to become objects of general notoriety.

Among other relations of this kind may be reckoned what is mentioned by Josephus in his Antiquities, who, in speaking of the progress that had been made in astronomy by Seth and his posterity, before the deluge, asserts, that they engraved the principles of the science on two pillars, one of stone and the other of brick, called the pillars of Seth ; and that the former of these was entire in his time. He also ascribes to the antediluvians a knowledge of the astronomical cycle of 600 years, which Mantucla, in his Historie des Mathematiques, thinks, with much greater reason, was an invention of the Chaldeans; and that whatever information was possessed by the Jewish annalist, with respect to this memorable period, was probably obtained either from that people, or from some ancient writings which no longer exist.”

Astronomy is a science useful and sublime in the highest degree. It is useful, not only on its own account, but as the foundation of other arts and sciences; and sublime, as it elevates the soul above the little objects of this world to scenes of infinite grandeur.

Navigation, as an art or a science, is dependent on the principles of astronomy. The varying compass would not form a sure guide to the mariner on the pathless ocean, were it not for corrections derived from observation on the heavenly bodies. Geography is equally dependent. By astronomy

are ascertained the figure and magnitude of the Earth. The knowledge of latitude and longitude, the situation and distance of places the most remote, the true bearing of countries in respect to each other, and their magnitude or extension, are most accurately obtained by astronomical principles. But above all, astronomy affords the most enlarged and sublime views of the Creator's works. In the vast expanse of the universe, the astronomer beholds the stars, which bespangle and adorn our canopy, magnified into so many suns, surrounded with worlds of unknown extent, constituting systems multiplied beyond the utmost bound of human imagination, and measured only by the omnipresence of Jehovah; all moving in harmony, in subjection to his omnipotent control. 66 The heavens declare the glory of God, and the firmament showeth his handy work." “ An undevout astronomer is mad."

There have been three great systems of astronomy--the Ptolemaic, the Brahean, and the Coperni

The former two, however, though dignified by the name of systems, are more properly denominated hypotheses.

The Ptolemaic system takes its name from Claudius Ptolemeus, or Ptolemy, who flourished at Alexandria or Pelusium in Egypt, in the second century of the Christian era, in the reigns of Adrian and Antoninus, the Roman emperors. In this system, the Earth was supposed at rest in the centre of the universe, around which the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn revolved. Above the planets this hypothesis placed the firmament of stars and the two crystalline spheres, all

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included in the primum mobile giving motion to the whole. Still higher, according to some, he conceived, was placed the empyrium heaven, or heaven of heavens; all revolving round the Earth from east to west in twenty-four hours, according to the ideas of the illiterate in all ages. (Plate 1. Fig. 1.)

The different phases of Mercury and Venus, their superior conjunctions without oppositions, and the apparent retrograde motion of all the primary planets, show the absurdity of this hypothesis.

Tycho Brahe was a native of Sweden, being born at Knudstorp, in the year 1546; though, from education and residence in Denmark, considered a Dane. This celebrated astronomer was acquainted with the Copernican system, published before his time. But, rejecting some of its most simple principles, because he thought them irreconcilable to the literal meaning of some texts of scripture, he adopted some of the greatest absurdities of Ptolemy, in other respects making his system agree with the rules of modern astronomy.

In his system the Earth is supposed at rest, the Sun and Moon revolving round it as the centre of their motion, while the other planets revolve around the Sun, and are carried with it about the Earth. (Plate 1. Fig. 2.)

By this hypothesis the phases of Mercury and Venus may be explained. But no satisfactory explanation can be given by it of the opposition of the superior planets. Both the Ptolemaic and Brahean systems are contrary to the modern principles of calculating and projecting eclipses.

The Copernican system is now universally adopt

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