Astronomy is the most ancient of the sciences. The study of the stars is doubtless as old as man himself, and hence many of its discoveries date back of authentic records, amid the mysteries of tradition. In tracing its history, we shall speak only of those

prominent facts that will enable us to understand its progress and glorious achievements.

The Chinese boast much of their astronomical discoveries. Indeed, their emperor claims a celestial ancestry, and styles himself the Son of the Sun. They possess an account of a conjunction of four planets and the moon, which occurred in the 25th contury before Christ. They have also the first record of an eclipse of the sun (B.C. 2128); and one of their emperors put to death the chief astronomers Ho and Hi for failing to announce the solar eclipse of 2169 B.C.

The Chaldeans.-The Chaldean shepherds, watching their flocks by night under a sky famed for its clearness and brilliancy, could not fail to become familiar with many of the movements of the heavenly bodies. Their priests were astronomers; and their temples, observatories. When Alexander took Babylon (B.c. 331), he found a record of their observations reaching back nineteen centuries.* The Chaldeans divided the day into hours, invented the sun-dial, and discovered the Saros, or Chaldean Period-the length of time in which eclipses of the sun and the moon repeat themselves in the same order.

The Grecians.-Though the Asiatics were patient observers, they did not classify their knowledge, and lay the basis of a science. This became the work of the western mind.

THALES (B.C. 640-548), one of the seven sages of

* Many astronomical inscriptions have been found in the ruins of Nineveh. In the public library of that city there was a series of about seventy-two volumes, called the Observations of Bel. One book treated of the polar star (then Alpha of the Dragon), another of Venus, and a third of Mars. The earliest of these records are thought to date back as far as 2540 B.C. (See Records of the Past, Vol. I.)

Greece, has been styled the Father of Astronomy. He taught that the earth is round, and that the moon receives her light from the sun. He determined when the equinoxes and the solstices occur, and also predicted an eclipse of the sun that is famous for having terminated a war between the Medes and the Lydians. These nations were engaged in a fierce battle, but the awe produced by the darkening of the sun was so great, that both sides threw down their arms and made peace.

ANAXIMANDER (B.C. 610-546) invented the sun-dial, and explained the cause of the moon's phases.

PYTHAGORAS (B. C. 570-500) founded a celebrated astronomical school at Crotona, Italy, where were educated hundreds of enthusiastic pupils.* He was emphatically a dreamer. He conceived a system of the universe, in many respects correct; yet he advanced no proof, made few converts to his views, and they were soon well-nigh forgotten.

He held that the sun is the center of the solar system, the planets revolving about it in circular orbits; that the earth rotates daily on its axis, and revolves yearly round the sun; that Venus is both morning and evening star; that the planets are placed at intervals corresponding to the scale in music, and that they move in harmony, making the "music of the spheres," but that this celestial concert is heard. only by the gods,-the ears of man being too gross for such divine melody. He also believed that the planets are inhabited, and he even attempted to calculate the size of the animals in the moon.

ANAXAGORAS (B.C. 500-428) taught that there is but one God, and that the sun is only a fiery globe, and should not be worshipped. He attempted to explain eclipses and other celestial phenomena by natural causes, saying that there is no such thing as chance or accident, these being only names for unknown laws. For his audacity and impiety, as his countrymen considered it, he and his family were doomed to perpetual banishment.

EUDOXUS, who lived in the fourth century B.C., invented the theory of the Crystalline Spheres. He held that the heavenly bodies are set, like gems, in hollow, transparent, crystal globes, which are so pure that they do not obstruct our view, while they all revolve around the earth; and that the planets are placed in one globe, but have a power of moving themselves, under the guidance-as Aristotle taught -of a tutelary genius, who resides in each, and rules over it as the mind rules over the body.

HIPPARCHUS, who flourished in the second century B.C., has been called the Newton of Antiquity. He was the most celebrated of the Greek astronomers. He calculated the length of the year to within six minutes, discovered the precession of the equinoxes, and made the first catalogue of the stars-1080 in number.

The Egyptians.-Egypt, as well as Chaldea, was noted for its knowledge of the sciences long before they were cultivated in Greece. It was the practice of the Greek philosophers, before aspiring to the rank of teacher, to travel for years through these countries, and gather wisdom at its fountain-head. Pythagoras spent thirty years in this kind of study.

Two hundred years after Pythagoras, the celebrated school of Alexandria was established.* Here were concentrated in vast libraries and princely halls nearly all the wisdom and learning of the world. Here flourished the sciences and arts, under the patronage of munificent kings.

At this school, Ptolemy (A.D. 70), a Grecian, wrote his great work, the Almagest, which for fourteen centuries was the text-book of astronomers. In this work was given what is known as the Ptolemaic System. It was founded largely upon the materials gathered by previous astronomers, such as Hipparchus, whom we have already mentioned, and Eratosthenes, who computed the size of the earth by the means even now considered the best-the measurement of an arc of the meridian.

Ptolemaic System.-To the early astronomers, the movements of the planets seemed extremely complex. Venus, for instance, was sometimes seen as evening star in the west, and then again as morning star in the east. Sometimes she appeared to be moving in the same direction as the sun, then, going apparently behind the sun, she seemed to pass on again in a course directly opposite. At one time, she would recede from the sun more and more slowly and coyly, until she would appear to be entirely stationary; then she would retrace her steps, and seem to meet the sun.

An attempt was made to account for all these facts by an incongruous system of "Cycles and

* See Barnes's General History, p. 154.