eclipse or shut it out; and when our earth comes exactly between the moon and the sun we cut off the sun's light from the moon, and see our own shadow passing over the moon's face, and thus we eclipse the moon.

Anaxagoras knew that the planets Jupiter, Saturn, Venus, Mars, and Mercury move in the heavens, and that the stars do not move. He believed that all the heavenly bodies were fiery stones; the sun he thought was a huge fiery stone as big as the Peloponnesus. He was the first scientific man who was persecuted for declaring boldly what he believed to be the truth. The Greeks were very angry with him for teaching that the sun was not a god; so he was tried at Athens, when quite an old man, and condemned to death. His friend Pericles pleaded for him, and the sentence was changed to a fine and banishment, and he retired to Lampsacus, where he went on teaching science and philosophy till his death.

Anaxagoras was the first Greek philosopher who taught that there must be one Great Intelligence ruling over the universe. So that the Greeks punished as an atheist the man who first taught them of a Supreme God. This example should teach us to be very careful how we condemn the opinions of others, for fear that we, like the Greeks, should think another wicked only because his thoughts are nobler than we can understand.

Hippocrates, 420.-While Anaxagoras was studying the heavens, another man, born about 420 B.C. in the little island of Cos, was studying men, and how to make their lives healthier and happier. Hippocrates, the Father of Medicine, belonged to a family of doctors and priests. The Greeks did not understand that illness comes to us because we do not know how to take care of our bodies.

CH. 11.

HIPPOCRATES-ARISTOTLE.

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They thought that every illness was a punishment sent because one of their gods was angry, so when they were ill they sent a present to the temple of Esculapius, the god of medicine, and then went to the priests of Esculapius to cure them. The ancestors of Hippocrates were all priests of Æsculapius, but he separated himself from the priesthood and devoted his time to studying the human body, and finding out the causes of disease. He studied the effect that heat and cold have upon us, and taught physicians to pay attention to the kind of food given to sick people, and espe cially to watch carefully in sickness for the critical point when the fever is at its height. He wrote many learned works on the human body, and you should remember his name as the Founder of the science of Medicine.

Eudoxus, 406-Democritus, 459.-The next great astronomer after Anaxagoras was called Eudoxus. He was born about 406 B.C., at Cnidos, in Asia Minor, where he had an observatory, from which he could watch the heavens, and by this means he made a map of all the stars then known. He was the first Greek astronomer who explained how the planets Jupiter, &c., moved round in the heavens, and the time at which they would appear again exactly in the same place as before. The great philosopher Democritus, of Abdera (459 B.C.), who lived about the same time as Eudoxus, made the remarkable guess that the beautiful bright band called the 'Milky Way,' which stretches every evening right across the sky, is composed of millions of stars scattered like dust over the heavens.

Aristotle, 384, one of the most famous philosophers of Greece, was also a great student of nature. He was born at Stagira, in Thrace, 384 B.C., but studied at Athens under Plato, and afterwards became the tutor of Alexander the

Great. Aristotle did much for astronomy, by collecting and comparing the discoveries of the astronomers who came before him. He is the first of the Greek writers who states very decidedly that the earth must be a round globe, and he discovered an eclipse, or occultation as it is termed by astronomers, of the planet Mars by the moon.

But the best scientific work of Aristotle was his study of animals. He persuaded Alexander the Great, who governed Greece at that time, to employ several thousand people to collect specimens of animals in all parts of Europe and Asia and to send them to Athens. Here Aristotle examined them and arranged them under different classes according to their organs, or different parts of their body, and the manner in which they used them. Many of Aristotle's divisions of the animal kingdom are still in use, and he may fairly be called the Founder of Zoology. He pointed out that we can trace an unbroken chain from the lowest plant up to the highest animal, each group being only divided from the next by very slight differences; nor can we tell, he said, where plants end and animals begin, for there are some forms which are so like both plants and animals that we cannot decide in which division to place them.

He also pointed out that the life in plants is much lower than in animals, for if you cut a plant into pieces, each piece will grow, showing that the parts of a plant are simple and do not depend very closely upon each other. But an animal, and especially one of the higher animals, is a most complicated piece of machinery. If you hurt or destroy any of the most important parts the whole body dies, and if you cut off any part whatever, that part dies as soon as it is separated from the rest. These and many other very interesting facts about animals are to be found in Aristotle's great

CH. II. THEOPHRASTUS THE FIRST BOTANIST.

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work on Natural History, which, however, you must remember, was only one out of many great works written by him on subjects which do not concern us here.

Theophrastus, 371.-Among the pupils of Aristotle was a man named Theophrastus, who was born at Eresus, 371 B.C. Theophrastus devoted himself chiefly to the study of plants, and is the first botanist whose name has been handed down to us. The Greeks understood very little about plants except those which they used for medicine; but Theophrastus described about 500 different kinds of plants, and divided them into trees, herbs, and shrubs. We know, however, very little about his writings.

CHAPTER III.

320 to 212 B.C.

School of Science at Alexandria-The Ecliptic and the Zodiac- Greeks believed that the Sun moved round the Earth-Aristarchus knew that it was the Earth which moved-He also knew of the Obliquity of the Ecliptic, and that the Seasons are caused by it-He knew that the Earth turns daily on its Axis-Euclid discovers that Light travels in straight lines - Archimedes discovers the LeverPrinciple of the Lever-Hiero's Crown, and how Archimedes discovered the principle of Specific Gravity.

WHILE Aristotle was studying science at Athens, the Greeks under Alexander the Great were making great conquests in Egypt, where Alexander founded a city bearing his own name on the shores of the Mediterranean. After Alexander's death this city, called Alexandria, fell to the portion of Ptolemy Lagus, one of Alexander's generals, who was suc, ceeded by a number of princes of the same name. The Ptolemies were all patrons of learning and science, and the school of Alexandria became one of the most famous the world has ever known. By this time the Greeks had learnt many astronomical facts, some of them probably from the Egyptians. They had traced the ecliptic, or the sun's apparent yearly path through the heavens, and, dividing this path into twelve parts, they called each division by the name of a constellation or cluster of stars. These constellations received most of them the names of animals, and therefore the circle of the twelve constellations was called the Zodiac,