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presenting the ecliptic and the other its axis. Open the sector to the radius of the first circle on the line of chords, and take off the chord of 5° 35', from D to E, or from the vertex of the axis of the ecliptic, to the right hand, because the moon's latitude is S. descending, but to the left hand if the latitude had been N. or S. ascending, and draw the line CE for the southern half of the axis of the moon's orbit. Bisect DE by the line CGg, on which set off the moon's latitude 32′ 21′′, taken from the same scale, from C to G, and through G draw the line NGP, for the path of the moon's center, perpendicular to CFE: then F will be the point, where the moon's center is at the middle of the eclipse, G the point where her center is at the tabular time of her being full, and H the point, where her center is at the time of the ecliptical opposition.

Take from the same scale the moon's horary motion from the sun, and with extent to an hour, graduate the moon's path into hours and minutes, marking the graduations so that the time of full moon, viz. 3h 50′ 50" may fall in the point G, where the bisecting line cuts the moon's path.

With the moon's semi-diameter 15′ 38′′ as a radius, from center F, describe a circle for the position of the moon at the middle of the eclipse, and also two circles from the centers N and P, in the line of the moon's path, for the positions of the moon at the beginning and end of the eclipse, when it is in contact with the earth's shadow, represented by the interior circle before described. The point N represents the instant when the eclipse begins, and the point P, when it ends; the first being at 2h 15' 10" A. M., and the other at 5h 18′ 0′′.5; the moon being eclipsed 10 digits.

The disk of the sun and moon is supposed to be divided into twelve equal parts, and the quantity of the eclipse is estimated in these parts.

THE FIXED STARS.

THE fixed stars are generally supposed to be the central suns of so many systems of planets, which revolve round them at different distances and in various orbits, deriving from them the benefits of both light and heat. They are said to be fixed, because they generally preserve the same relative distances from each other.

The number of those that are visible to the naked eye is less than one would imagine, from a cursory view of the heavens. The British catalogue of them, which is the largest, contains but 3001, of which many are invisible to the naked eye, being only discoverable by the telescope, and thence denominated telescopic stars. They shine with native and inherent light, for otherwise they would be invisible; as their distances from us are inconceivably great. Dr. Bradly says, from his observations, that if they had an annual parallax of a single second he must have discovered it. How immensely great then, must their distances be, when the diameter of the earth's orbit, which is near two hundred millions of miles, does not subtend an angle of a second at the distance of the nearest of them; hence not less than 40 millions of millions of miles! Their twinkling appearance is occasioned by their momentary occultation, by every particle of dust that floats in our atmosphere. To the naked eye they appear of a sensible magnitude, which is destroyed by a good telescope, as no micrometer can measure their diameters. The rays which the eye receives from them are not all

collected accurately into a point on the retina, but are diffused over a circular space around the spot where the image is formed, and by their vibrations or impressions on that space, cause us to imagine them to be larger than they really are.

From their apparent magnitude, astronomers have distinguished them into six or seven different magnitudes. And for the convenience of distinguishing them from one another, they have ranged them into different combinations, under various particular names, which combinations are called asterisms or constellations. Twelve fill that space which is called the zodiac, and are denominated Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius, Pisces; lying eastward of each other in this order, and each extending over a space of thirty degrees, and of the breadth of about 16 degrees, comprehending all the stars in that space. The number of the ancient constellations was 48, but on our present globes, they are near 70, each star having, by the contrivance of Boyer, a letter annexed to it, whereby it is easily distinguished; the first letters of the Greek alphabet being applied to the brightest, and so on through the whole; and then the letters of the Roman alphabet.

The Milky Way is a luminous tract surrounding the heavens, arising probably from the confused refulgence of innumerable stars disseminated through that part, as they are visible in great numbers through a good telescope; although some astronomers are of a different opinion.

Cloudy stars are so called from their misty appearance to the naked eye, by which a star or two are dimly seen; but through a good telescope they seem

to be broad illuminated parts of the heavens, in which one or more stars are seen. There is one in the right hand of Perseus,-one in the middle of the Crab,one near the sting of Scorpio,-three in Sagittarius, in his eye, bow, and right shoulder,-two in Orion, in his head, and in his sword; and the Magellanic clouds near the south pole, where the stars shine as through very thin clouds; also one between the great and little Dog, very full of little stars. In the first of these, there appear more stars, than in any others, although 21 have been counted in the head of Orion, and above forty in the Crab. The most remarkable of them is that in the sword of Orion, which seems like a gap in the heavens, through which we look, as it were, into a much brighter region. Seven stars are seen in this luminous space. Although these spaces appear to us to be very small, yet they must, in fact, be very large,-probably more extensive than our whole solar system.

Several stars have been observed to appear and disappear periodically, others to suffer a periodical diminution and increase of splendour, and others to have disappeared entirely. Gemma observed one in the chair of Cassiopea, in November, 1572, surpassing Sirius in splendour and magnitude, but gradually decaying till the month of March following, when it became invisible.

Kepler, in the year 1604, discovered a star near the right heel of Serpentarius, surpassing Jupiter in magnitude and lustre, which disappeared between October, 1605, and February following, and has not been seen since. Jansenius, in the year 1600, discovered one in the breast of the Swan, which in time became so small as to disappear entirely. In the years 1657, 1658,

1659, it recovered its former splendour, but soon decayed; its period is about 18 years. The Stella mira in the neck of the whale, first observed by Fabricius in August, 1596, has been observed to appear and disappear periodically, seven times in 6 years, its period being 333 days; continuing for 15 days in its greatest lustre, and never quite extinguished. In 1686, Kirch discovered a new star in the Swan's neck, which returns periodically in 404 days. There is also a star in the Swan, whose lustre is alternately increased and diminished in every twelve days.

Some have supposed, that the appearing and disappearing of these stars may be accounted for, upon the supposition of their having large spots upon their surfaces, which render them invisible when these spots are turned towards the earth: and when their rotations on their axes turn these spots from us, they begin again to appear. Others, from their quick rotations on their axes, may acquire such a centrifugal force, as will occasion them to assume the form of millstones, or of Saturn's ring, which will make them visible only when their sides are turned towards our earth. Some have thought also, that the sudden blaze observed in some of them might be accounted for, by supposing some of their comets to have dropped into them, to supply their exhausted fuel.

Some of the stars, such as Capella, Sirius, Procyon, and particularly Arcturus, are observed to change their places, above a minute of a degree, with respect to others. But whether this arises from any real motion in the stars themselves, or to our whole solar system's changing its place in universal space, must require the observations of many ages to determine. If our whole system be changing its place, as some late observa

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