historical record, are placed with particular regard to the four cardinal points.

The Phoenicians first applied astronomy to the purposes of navigation; steering by the constellation called the Little Bear, and by that immovable point called the Pole Star.

The origin of astronomical knowledge among the Greeks is not known. Homer and Hesiod lived about 870 years before the Christian era. Hesiod advises the farmer to regulate the times of sowing and harvest by the rising and setting of the Pleiades; and Homer says that the constellations, the Pleiades, Orion, and Arcturus, were used in navigation. Thales, who lived about 640 years before our era, predicted an eclipse, which happened just at the moment when two armies were about to engage in battle, and being regarded by both as a bad omen, they desisted: this prediction showed great astronomical knowledge.* Pythagoras flourished about 590 years before our era; he taught that the Sun is in the centre of the universe-that the Earth is round— that the Moon reflects the Sun's rays, and is inhabited, -that the Stars are worlds—and that Comets are wandering Stars; and Philolaus, about 150 years after, taught that the Earth moves round the Sun. The opinions of Pythagoras were held by some of his pupils, but are either too contradictory, or not sufficiently ob

*The ancients were enabled to foretel eclipses of the moon by means of watching constantly her motions for a long succession of years; by which they ascertained her periods. The Chaldeans, says Bailly, who watched without ceasing, in the study of the heavens, and whose astronomers succeeded each other successively, like centinels, must have permitted few eclipses to pass without observation.

vious, to the sight, to have been maintained in continual succession. Plato and Aristotle afterwards taught that the Earth is in the centre; and this opinion long continued to prevail: for Ptolemy, who lived in the first century of the Christian era, taught that the Earth is immovable in the centre, and that the whole starry sphere revolves around it in 24 hours; that the planets move round the Earth, each, in proportion to its distance, in a vast, solid, transparent globe, having the planet sticking upon its surface: and, as these transparent globes did not account for all the apparent motions of the heavenly bodies, he contrived other and still more complicated machinery, to allow for these appearances. This absurd doctrine was maintained nearly 1500 years; that is to say, until within the last 300 years.

During the first 1000 or 1200 years of our era, Europe was almost entirely ignorant of astronomy and every other science. In 1215 appeared the first English book on this subject, compiled chiefly from Ptolemy, and preserved its reputation for nearly 300 years. During this period a love of science prevailed in Europe, and Astronomy was cultivated. In the year 1530, appeared the famous work of the celebrated Nicolas Copernicus, a native of Poland, who restored the doctrine taught by Pythagoras more than 2000 years before, and gave the death blow to the system of Ptolemy. That of Copernicus still prevails: he taught that the Sun is in the centre-that the Planets, of which our Earth is one, revolve about the Sun at different distances, in different periods of time, and with different velocities. Copernicus, then, taught nearly the same doctrine as Pythagoras and his pupils; and hence, he is more properly illus

trious as the restorer, than as the founder of the system called the Copernican, which now prevails; and which, from time to time, has received accession of fresh discoveries, tending to establish its truth incontrovertibly. About a century afterwards, Galileo was condemned as a heretic for asserting the truth of this system, and imprisoned. But what may not be expected from superstition and bigotry! Pope Calixtus the 6th, when a large comet appeared, included the comet, and his enemies the Turks, in one anathema; and that anathema was a prayer.

Soon after the work of Copernicus appeared, Tycho Brahe, a Danish astronomer, rejected his system on other and more pious grounds. He conceived that the literal meaning of some parts of the Scriptures forbid the belief of the earth's motion around the sun;* and

* Lalande, an eminent French astronomer, says "It appears surprizing, that one of the principal obstacles to the Copernican system should have proceeded from that passage in scripture, in which it is said that Joshua desired the sun to stand still. To suppose that Joshua spoke in philosophical language, unknown both in his country and in his time, would be to exclude from the Bible all those expressions which are used in society, and which no one pretends to misunderstand. Astronomers, as well as others, say, that the sun rises and sets, and will continue so to say to all eternity, without attempting to deny the real state of nature, and the immobility of the sun. It would be folly to suppose that the general of an army, such as Joshua, at a moment when he was anxious to manifest the majesty and power of God to his soldiers by a great victory, should have thought proper to give them a lecture on astronomy; and, quitting the language his soldiers understood, desire the earth to stand still; he must at the same time, have entered into an explanation of this singular expression, and certainly no digression could have been more misplaced. Therefore, even supposing that Joshua spoke as a

anxious not to do violence to the sacred record, he sought for some theory which might be consonant with it. Concluding the earth to be immovable in the centre, he supposed that the sun with the planets moving around it (a doctrine he acknowledged), moved around the earth. This theory was not of long duration.

Some of the most important discoveries that have been added to what now is called the Copernican system, were made about the year 1620 by Kepler, one of the greatest astronomers that ever lived. By long and accurate observation of the motions of the planets, it was found both by him and by many preceding astronomers, that they do not always move with the same quickness, with the same velocity; and hence, Kepler, proceeding to inquire into the laws of moving bodies, discovered the very law by which the planets move, which governs their velocity, and proving that they do not move in circles round the sun; for if they moved in circles, they would always move at the same rate, for a reason that will be explained when we come to speak of Gravity; and it has since been found that the law discovered by Kepler explains the motions of all the planetary bodies equally well. This important law cannot be thoroughly illustrated without the assistance of trigonometry and geometry; nevertheless, I shall hereafter attempt a familiar explanation of it. Kepler, then discovered that the planets do not move about the sun in circles, but in ovals. He hinted at the power of gravity, and that this power caused the tides in our ocean.

prophet, and had been instructed by the power of God in things of which others were ignorant in his time, and particularly in his country, he could not have expressed himself otherwise than as he did."

About half a century afterwards, that truly great man, Sir Isaac Newton, by the discovery of the power of gravity, and the application of Kepler's law, raised the truth of the Copernican system, by mathematical demonstration, to its utmost pitch. About this time also, the invention of telescopes gave a new impulse to the science by the aid they afford to the eye of the astronomer, not only in discovering numberless fixed stars învisible to the naked eye, but also the forms of the planets. Rapid advances were also about this time made owards bringing to their present state of perfection, the various instruments used by the astronomer, as well as certain discoveries in the mathematics, as of fluxions by Newton, and logarithms by Lord Napier, tending greatly to shorten the previous methods of calculation. In England the discoveries of Newton were received with enthusiasm, but in other countries they were not so readily accepted. By slow degrees, as they became more generally intelligible by the commentaries of other mathematicians, they advanced in acceptation, and are now universally established. The purely mathematical mode of treating the subject adopted by Newton, being beyond the reach of the greater part of the scientific world, his discoveries were at first considered by many to be only the flights of an irregular, but irresistible genius. But the Marquis de L'Hopital, one of the greatest mathematicians of that day, being forcibly struck by the unrivalled demonstrations of Newton, inquired whether he ate, drank, and slept like other men.

The Copernican system, then, consists of the Sun, and of the planets and comets moving around it; the Sun