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trary direction. Of course, if the spectator is moving on the earth from west to east, the distant stars will appear to move from east to west.
The rising snd setting of all the distant heavenly bodies will, hence, be easily understood. The earth turns completely round every twenty-four hours; every inhabitant of it will, therefore, be carried round towards all the bodies out of it, and distant from it, every twenty-four hours. Hence, the rising and setting of the sun; the succession of day and night; and al: the dependent phenomena.
This progression of the whole heayens from east to west; the rising of some stars in the east, and the setting of others in the west; are objects which, viewed in this manner, will leave impressions much stronger than the mimic representaLion of the same phenomena on the celestial globe. The immensity of the great vault of heaven, the still, solemn, uniform motion; the accompanying association of the immeasurable distances, the apparent perpetuity, and the countless numbers of the stars, will fill the mind with reverence and devotion towards the omnipotent; infinite and eternal AUTHOR of the whole !
Having thus obtained ocular demonstration of the motion of the stars from east to west, or rather of the motion of the earth in the contrary direction, it will then be necessary to attend to another circumstance which is a consequence of that motion.
A slight consideration will evince, that the stars immediately above the axis on which the earth may be supposed to turo, will appear to remain stationary over those places, at both ends of the axis. In turning a wheel on a fixed axis, all the parts of the circumference will successively present themselves to different objects, but the axis will continue to point to the same place. If the wheel be supposed to be a globe revolving on an axis, the effect will be the same; the point of the axis, called the pole of the globe, will point to the same spot, while all the parts will perform smaller or larger circuits, in proportion as they are removed in a greater or less degree from the poles.
It is important, then, to be able to determine the points in the heavens which are opposite to the poles of the earth ; these always appear to stand still, while the other stars appear to make a daily circuit round them. As, however, we can only see 90 degrees in the heavens from the point over our own heads, the inhabitants of no part of the earth can see both poles,except those who live at the equator, from which both poles are disa
tant ninety degrees. The poles of the heavens may therefore be seen at the equator, exactly in the horizon, in the north and south ; but if you travel or sail one degree to the north of the equator, so as to be within 89 degrees of the north pole, you will, of course, see one degree beyond the north pole, and not so far as the south pole by one degree ; because, as before stated, you can always see 90 degrees in the heavens, from your zenith, or place over head. In New. England which lies between 40 and 45 degrees from the equa. tor, or within 45 and 50 degrees of the north pole, we always see 40 or 45 degrees beyond or below the north pole; or, in other words, the north pole in the heavens, or the stars immediately over the north pole of the earth, will be 40 or 45 degrees high.
At about midway between the horizon and the zenith, in this northern part of the heavens, we who are in New England must look for the north pole of the heavens, or the part which never appears to move. It happens that there is a star so near the north pole, that for all ordinary purposes it may be taken for the north pole itself; and this star may always be found very easily, by means of two other stars which point to it in a right line. During the winter months, these stars. which are in the constellation of the Great Bear, are to be found with the other stars of that remarkable constellation, on the eastern side of the pole. They are about six degrees asunder, and the nearest is five times that space, or thirty degrees from the polar star, at which they seem to point, and are, thence, called the Pointers.
The north pole star being thus found, it will be a pleasing employment to observe, that all the stars appear to move round it,according to their several distances, while it constant. ly stands still. An hour's contenuplation of this star, and of the motions of the rest of the heavens, while it remains an immoveable centre, will teach more to the uninformed in as. tronomy, than a thousand lessons or lectures in the closet.
On a winter's evening, the other remarkable objects in view, will be the Pleiades, or seven stars, in the southeast; and below them, a little to the east, the grand constellation of Orion : and still lower, the dog star Sirius, the brightest of all the fixed stars. The three bright stars together in a line, called the Belt of Orion, are at about equal distances from the Pleiades and Sirius; that is, about twenty-five degrees from each. Besides remembering this distance, and that of the Pointers, before mentioned, for the sake of occasional comparisons, it will be useful to recollect, that the most northern of the three stars in the Belt of Orion, is exactly over the equator, so that from that star to the north pole star is exactly 90 degrees.
The Pleiades are in the Zodiac, on the south side; and so is the red star Aldeberan, near them; and the two bright stars about forty degrees to the left, called Castor and Pollut, or the Twins, are also in the Zodiac, and about five degrees north of the sun's place, on the 12th of July.
On such an evening, the Milky-way will be seen extending from north north-east to west south-west, as a light cloud ; supposed by some to be formed of a mass or shoal of stars, almost infinite in number, but indistinct from their distance ; though others suppose it to consist of a luminous space, and not of stars.
A celestial globe, rectified to the day and hour, will point to other objects; an ephemeris will indicate the names or places of the planets which may then be above the horizon; and any telescope will render visible many other interesting and wonderful phenomena.
Should the moon be visible, the motion in her orbit may be nightly traced by her approximating to, or receding fron, certain stars; and the same may be observed in the motion of the planets in their orbits.
The morning and evening stars are the bright planets, Venus and Jupiter, so called from their rising or setting with the
Mars is red; Saturn of a leaden colour; Herschel is so distant, and Mercury is so near the sun, that they can seldom be seen but with a telescope.
Very small telescopes will shew most of the celestial phenomena; Jupiter's moons, Saturn's ring, the moonlike phases
267. The stars, according to their distances, are of seven sizes, called first magnitude, second magnitude, &c. down to the seventh magnitude, which can only be seen with a telescope. The stars may be distinguished from the planets by their twinkling; whereas the planets have a steady light.
Obs.-Having now acquired some knowledge of the wonderful things around the EARTH, which surpass the conception or imagination of man, we will return again to it, observing, that these fixed stars and other celestial objects are constantly made use of to determine the relative situation of places; and that they are unerring guides both in regard to time and place.
268. Besides the motion round the sun in their respective years, the earth and the planets also turn round on their own axes and by turning to and from the sun, produce to their inhabitants, alternate light and darkness, or day and night; so that their seasons and years are produced by the grand revolution round the sun; and their days and nights by turning on their
Obs. If a boy throw a ball out of his hand, besides going forwards, it turns round on its axis, and this is the precise motion of the earth and planets. So likewise the ball of a bill. iard table moves onward, and also turns on its axis.
269. The distances of the seven primary planets from the sun, in round millions, are- -Mercury 36, Venus £ 68, Earth 95, Mars 142, Jupiter 4 486, Saturn ħ 892, and Herschel 1,800 millions miles from the sun.
Their diameters are respectively 3, 8, 8, 4, 89, 79, and 35 thousand miles.
And their periods of revolution are 3, 7, 12, 22, 144, 340, and 1000 months.
270. In their grand orbits, the planets do not move exactly in the same level or plane; but each moves regularly in its own level. Nor are their axes exactly perpendicular to the plane of their orbits, but variously inclined; and this inclination produces the difference of their seasons, and the different lengths of day and night.
271. The whole earth is calculated to be 4; times heavier than water; the Sun, Jupiter, and Herschel about the weight of water; Mercury nine times, and Venus six times heavier. In this way, taking matter