convenience of location they divided the whole sphere of Stars into constellations or groups, in many cases affixing fanciful names to the group, although, in most instances, not the faintest resemblance existed between the namesake and the shape of the constellation. Then they named the Stars by the letters of their alphabet. Thus, the nearest Star to the Earth is the principal Star in the constellation of the Centaur, and therefore Alpha, the first Greek letter. As the telescope has discovered additional Stars in each constellation, it has been necessary, after exhausting the Greek alphabet, to use our own, and after that to begin numbering them with figures, as 61 Cygni - that is, No. 61 of the Swan.

Let us go out some clear night. We all know the Big Dipper. Let us talk some about that. There is a satisfaction in knowing that we see before us an object which has not perceptibly altered since the beginning of history. Without traversing seas and continents, we gaze upon the same spectacle that has claimed the wondering attention of Confucius, Herodotus, Pythagoras, Socrates, Plato, Aristotle, Alexander, Ptolemy, Mithridatés, Hannibal, Marius, Julius Cæsar, Cleopatra, Charlemagne, Charles the Fifth, Elizabeth, Shakspeare, Frederick, and Napoleon. All these mighty of the Earth have looked upon this same group of Stars. It is the most prominent in the northern heavens, both on account of the brilliant Suns which go to form it, and from the fact that, of all the distinctively-marked groups, it never sinks beneath the horizon in our latitude. This constellation was called Arktos (Greek for Bear) and Hamexa (Wagon) in the time of Homer, the father of poetry, who lived a thousand years before Christ. There are seventeen Stars visible to the eye in this constellation, astronomically speaking, but to us, and to the World which is gone, seven bright Stars give to it its shape, six of them forming a dipper, and one of them hanging down a little, giving the handle a crooked appearance, if we are inclined to attach it to the other six (as people always have done), though the writer never considered it to help out the dipper in any way. The people of Rome, of course, translated Arktos into their word for "Bear," which was Ursus.

Now, as there was another constellation of the Bear, of which the Pole Star was a member, they called the Pole constellation the Little Bear (Ursa Minor), and the constellation of the Big Dipper Ursa Major (the Greater Bear). As there is a constellation higher in the sky which is seen much of the year, and which is exactly like the Big Dipper in shape on a smaller scale, it has always seemed odd to some people that it should not have received the name of Ursa Minor, instead of the group around the Pole. But the Little Dipper is called the Pleiades, and is spoken of in Job. The Sun passes by the constellation in which it is situated. To come back to the Big Dipper: If the reader who does not know where the Big Dipper is placed will ask a friend to go out with him and point it out, he will go on the north side of his house, and there, spread before him, not very far up the heavens, he will have six great Stars, spread wide apart, but making as perfect a dipper as any one could mark out with six dots. Now, if you do not know where the North Star is, take the two Stars furthest from the handle of the "Dipper," and, looking upward from the bottom of the Dipper about four times as far as the distance from the bottom to the top of the Dipper, you run directly to the North Star, the three Stars being in line. The two end-Stars in the Dipper are called the Pointers on this account. Around this North Star all the heavens seemingly revolve, which is owing to the fact that the Earth is spinning around under the Star. The Romans also called the seven bright Stars of the Big Dipper the Septentriones, or the Seven Ploughing Oxen, from which the Latin word septentrionalis sprang, which, long as it is, means nothing but "north," and has also been adopted into French, Spanish and Italian with the same meaning. The common names throughout Europe for the Big Dipper, or Ursa Major, are the Plow, Charles' Wain, and the Wagon, retaining the old Greek idea. These names are frequently heard here, even among common folk. "Wain" means "wagon." Let us begin to name the Stars of Ursa Major. The first Star is nearest the North Star, at the top of the basin of the Dipper, furthest from where the handle joins. This is Alpha Ursa Majoris in As

tronomy (Alpha of Ursa Major), a Star of the first magnitude. (though not so marked by all Astronomers) and furnishes the inexperienced eye with an opportunity to fix the meaning of the term "first magnitude." There are seven Stars of this rank in the northern heavens. Below, forming the outer end. of the bottom of the Dipper, is Beta, the second; at the other end of the bottom is Gamma; at the junction of the handle with the basin is Delta; running up the handle, the eye rests on Epsilon; and at the end of the handle is Zeta. This Star is closely surrounded by three little Stars, at least one of which everyone may see on a winter night. Sharpereyed people may, perhaps, see the others-they are there, close up. Now those seemingly little Stars may be as large as Zeta, or they may be nearer, being much smaller and less resplendent with light— no one can tell. Their distance apart sidewise, although the eye does not detect a great deal, is probably sufficient to swing a dozen Solar Systems in. Now, dropping obliquely, lies Eta, completing the group, and making the handle of the Dipper crooked, although what it may have contributed to the Bear of the heathen, the Plow of the middle ages, or the Wain of the past century, is more than the writer knows. Now, draw a line from the North Star to Eta. Continue that line as far again, and you strike the Star Arcturus, another one of the first magnitude, whose distance is unknown, as a base-line 92,300,000 miles long gives no angle, the telescope pointing straight out from each end. Beta and Gamma (the bottom Stars) are of the second magnitude; Delta, Epsilon, Zeta and Eta are of the third magnitude. The North Star is not a Star of great brilliancy (third magnitude), but is easily recognizable as a fairly-bright point in a large field where there are no Stars above the fifth magnitude at all. This Star is Alpha Ursa Minoris, and is almost directly over the North Pole. When the Arctic explorer stands on the North Pole, the North Star will be over his head. It sinks toward the horizon as you go southward. There is no Star so closely to the South Pole which can be seen with the naked eye. Owing to certain great motions of the Earth's orbit, as it were, the tip of the Earth gradually

changes. The reader has noticed the handle of a top describe a small circle as it spinned. The imaginary line called the Pole does the same thing, revolving once in eighteen years. around the North Star. This is called nutation. But there is another and vaster motion caused by this nutation, which takes thousands of years for its accomplishment. The laws of attraction complicate the motions of all the heavenly bodies in a remarkable degree. One of these "motions of the orbit" might be fairly illustrated if one took a hoop and swung it around on his finger. If he called his finger the Sun, and the furthest portion of the hoop aphelion (away from the Sun), and the part his finger touched perihelion (nearest the Sun), then, by making the hoop revolve on his finger, he would see that perihelion constantly changed-that is, if there were a blotch of printer's ink at aphelion, he would, after swinging the hoop sharply twenty or thirty times, find his finger very thoroughly blackened. Of course, if he could hold his finger a third of the way across the hoop in the air, and still do the swinging, it would be more exact. Thus, the exact spot in which the Earth is nearest the Sun is constantly changing, and only once in 25,868 years does the Earth occupy the same spot in space twice when it is at perihelion. This may, perhaps, be explained: This change is called the Precession of the Equinoxes. There is not probably in all Astronomy an expression so thoroughly formidable to the uninitiated mind. But let us cut up these high-sounding words. We all know what "precede" means, but we rarely see the word changed as we change "succeed"—that is, into precession. If I precede you in going to dinner, it is a precession of individuals. The word nor meant "night" among the Romans. The reader can detect the word "equal" in "equi"-so that "equinox" means equal night. But "equinox" is one of those words which, after it has been dissected, is still as blinding as ever; so we must still investigate it. Let us take an apple and run a knitting-needle through it. Run the knitting-needle into the rest of the apples in the tureen which may be supposed to hold them on a winter's night, letting the knitting-needle "stand over" pretty well out of a

III

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vertical position. The chances are that it will hold its position, and fairly represent the position of the Earth. Now, for convenience, take the lamp in your hand and walk around the apple, which should stand well up from the other apples to get a full light. Suppose you begin with the apple leaning away from you. Then a portion of the under part of the apple beyond the needle is lighted, and a portion on the front side of the top is dark. As you walk either way round, just a quarter of the whole circumference, you have arrived at a point where your lamp throws light exactly to the knitting-needle both at the top and bottom. As the apple must be supposed to be revolving on the needle, it is plain that each side of the Earth will get the light and darkness in exactly equal proportions, and that the night cannot be any longer than the day. This is an equinox. There is one on the other side of the table, also. Now this illustration has reversed the real operation of the equinox, but, if the reader set his light down and carry the apple in the same position, he can get the exact effect. The poles must point the same way all the time of the revolution around the table. If the orbit of the Earth were a circular crevice cut in your floor, and the knitting-needle, standing in the same leaning position, were pounded out flat and two inches wide, and carried in its polar position around on top of the crevice, there would be but these two equinoctial points where it could slip down into the crevice without straightening up erectly. At those points it would go down sidewise. Of course it would be supposed that these two points would always be reached "on time," but as there is a certain Star out behind each equinoctial point, it was soon apparent to Astronomers that the days began to, say, "grow long" before the equinoctial point, registered hundreds of years before, had been reached. So it was found that the old Earth really lagged. It was as though the farmer plowing around the sapling near noon-time, got unendurably hungry in front of his neighbor's place instead of on the side nearest home. This would be a precession of stopping-places. Now if we take and bake this apple into a jelly-like condition, and then, by some means, whirl it on the knitting-needle, we will