Signs and Constellations do not Agree. By the precession of the equinoxes, as we have before described on page 106, the signs have fallen back along

The Signs and Constellations, as they now Compare in the Heavens, the former having fallen back, and the latter apparently advanced, 30° each.

the ecliptic about 30°, so that those stars which were, during the infancy of astronomy, in the sign Aries () are now in Taurus (8), and those which were in the sign Pisces (*) are now in Aries (~).*

Permanence of the Constellations.-The general appearance of the constellations and the figures

*If the teacher will put a pin at the center of Fig. 86, and then draw a sharp knife between the signs and the constellations, so as to detach the middle of the cut, and cause the inner part to revolve, the signs may be turned before any constellation, and thus this change be clearly apprehended.

which the stars form are due to the position we occupy. Could we cross the gulf of space beyond Neptune, the stars now so familiar to us would look strangely enough in their new groupings. As one in riding through a forest sees the trees apparently increase in size and open up to view before him, while they decrease in size and close in behind him, forming clusters and groups which constantly change as he passes along, so, as our earth travels with the solar system on its immense sidereal journey, the stars will gradually grow larger and brighter in front, while those behind us will appear smaller and dimmer.

Since, in addition to this, the stars themselves are in motion with varying velocity and in different directions, the constellations must change still more rapidly, so as ultimately to transform the appearance of the heavens. In time, the "Bands of Orion" will be loosened, and the "Seven Sisters" will glide apart. Such are the distances, however, that, although these movements have been going on constantly, no variation has occurred, since the creation of man, that is perceptible, save to the watchful astronomer. Nothing in nature is so invariable as the stars. They are the standards of time. Myriads of years must elapse before new maps of the constellations will be required.

Value of the Stars in Practical Life.-"The stars are the landmarks of the universe." They seem to be placed in the heavens by the Creator, not alone to elevate our thoughts and expand our conceptions of the infinite and eternal, but to afford us, amid the

constant fluctuations of our own earth, something unchangeable and abiding. Every object about us is constantly shifting, but over all shine the "eternal stars," each with its place so accurately marked, that to the astronomer and the geographer no deception is possible. To the mariner, the heavens become a dial-plate, the figures on its face set with glittering stars, along which the moon travels as a shining hand that marks off the hours with an accuracy no watch can ever rival. Standing on the deck of his vessel, far out at sea, a single observation of the sun or the stars decides his location in the waste of waters as accurately as if he were at home, and had caught sight of some old landmark he had known from his boyhood. In all the intricacies of surveying, the stars furnish the only immutable guide. Our clocks vainly strive to keep time with the celestial host. Thus, by an evident plan of the Creator, even in the most common affairs of life, are we compelled to look for guidance from the shifting objects of earth up to the heavens above.

ANCIENT VIEWS.-Anaximenes (500 B. c.) thought that the stars were for ornaments, and were nailed like bright studs into the crystalline sphere. Anaxagoras considered that they were stones whirled up from the earth by the rapid motion of the ether, and that its inflammable properties set them on fire and caused them to shine as stars. Some schools of the Grecian philosophers-the Stoics, Epicureans, etc.— believed that they were celestial fires kept alive by matter that constantly streamed up to them from the center of the heavens. The stars were at one

time said to feed on air; at another, to be the breathing holes of the universe.

Three Zones of Stars.—If we recall what was said on page 90, concerning the paths of the stars and the appearance of the heavens at different seasons of the year, we shall see that the constellations are naturally divided into three zones. The first embraces those which are visible through the entire year; the second, those whose paths can be seen only in part on any given night; and the third, those whose paths just graze our southern horizon, or never pass above it.

II. THE CONSTELLATIONS.

I. The Northern Circumpolar Constellations are visible in our latitude every night. They may be easily traced by holding the book up toward the northern sky in such a way that Polaris and the Big Dipper on the map and in the heavens agree in position, and then locating the other constellations by comparison.

As the stars revolve about Polaris, their places will vary with every successive night through the year. The cut represents them as they are seen at midnight of the winter solstice. At 6 P. M. of that day, the right-hand side of the map should be held downward, and the Big Dipper will be directly below the north star. At 6 A. M., the left-hand side should be at the bottom, and the Dipper will be above Polaris. From

day to day, this aspect will change, each star coming a little earlier to the meridian, or to its position on the preceding night. The rate of this progression is six hours, or 90°, in three months.

Ursa Major is represented under the figure of a great bear. It contains 133 stars visible to the naked eye. This constellation has been celebrated among all nations. It is remarkable that the shepherds of Chaldea in Asia and the Iroquois Indians of America gave to it the same name.