The conclusion becomes unavoidable, that the fixed stars shine with unborrowed light; that they must be vast luminous bodies like our Sun; and that they may be centres to retinues of planets and comets, as numerous, and as full of beauty and of being, as those in attendance on our Sun.

The stars in each constellation, which have not specific names, are called by the names of letters in the Greek alphabet; the largest Alpha, the next Beta, the third Gamma, &c. If there are more stars in a constellation than Greek letters, Italic letters are used. Alpha in one constellation, may be of a different magnitude from Alpha in another.

While there is a variety of hues in the light emitted by the fixed stars, there are variations of magnitude in some of them. Dr. Herschel concludes this variation is occasioned by inequalities of luminous matter on their sides; and that their rotation, on their axis, presents at one time the most luminous side, at another the least luminous.

One instance will be here introduced. Mr. Goodrick discovered that the star Beta in the constellation Lyra, is subject to the following periodical variation. It completes all its phases in 12 days and 19 hours, during which time it undergoes the following changes. 1. It is of the third magnitude for about 2 days. 2. It diminshes 14 days. 3. It is between the fourth and fifth magnitudes, for less than a day. 4. It increases about 2 days. 5. It is of the third magnitude for about 3 days. 6. It diminishes in about 1 day. 7. It is something larger than the fourth magnitude for a little less than a day, 8. It increases in about one day and three quarters to the first, and so completes a whole period. See Phil. Trans. 1785. Irregular variations, in the magnitudes of some stars, have been observed.

Many of the stars, which to the unassisted eye appear single, are proved by the telescope to be

What conclusion must we form respecting them? What seems probable?

What use bave astronomers made of Greek and Italic letters? What is supposed to be the cause of apparent. varying magnitudes in some of them?

double stars. Not apparently double, because one star is seen almost in the same line with another, though two or three times as distant, but double, because they are near to each other, and are revolving round a central point between them, in periods of three, five, ten, or fifteen centuries. Observations made for 40 years by Dr. Herschel, have established these facts.

Why may not these be centres of binary systems, where planets may be illuminated, and warmed, and fertilized by two Suns? Dr. Herschel has formed a catalogue of more than 400 such double stars; a few of which will be given.

German astronomers have much increased the catalogue of double stars.

Two large stars in the constellation Orion (known in popular language as the Yard and L.) are double stars; unequal in their magnitudes and varying in their colors. The stars Alpha, Beta, and Delta, in Hercules, are double stars. The stars of the first magnitude, Aldebaran in Taurus, and Castor in Gemini, are double stars. The north polar star is double, consisting of a larger star, white in color, and a smaller star, red in its hue.

Other remarkable phenomena in the heavens, must not be overlooked. There are treble, quadruple, and quintuple stars. Three, four, five, and sometimes more, appear revolving round a common centre among themselves, forming systems of material worlds, variegated to an extent beyond what the imagination of man can conceive.

Such stars are found in Ursa Major, Canis Major, Orion, and others of the constellations. A still more remarkable appear ance has been discovered in Orion. Its discoverer called it a luminous circular window, of more than 100 millions of miles

What is said of double stars and the period of their revolu

tion?

How many double stars have been discovered? Where may some of them be found?

What other remarkable phenomena deserve to be noticed ? What is said to be visible, with a telescope, in Orion?

in diameter, through which, we catch a glimpse of a more brilliant universe beyond. Where that bright portal leads, and what are the material glories which faintly gleam on mortal vision, who can tell?

Already by the aid of the telescope, our thoughts are contemplating many thousands of stars, each one of which must be a Sun. But the whiteness of the Galaxy, when viewed by Dr. Herschel's large telescope, is resolved into stars so numerous, that probably more than 10 millions belong to that single zone of suns, of which our Sun is supposed to make one.

They are thought to be in motion round their common centre of gravity, and that this accounts for the motion of our system towards the constellation Hercules. Extended as the material universe thus seems, we must not stop our investigations here. Twenty-five hundred other fields of light in the heavens called nebulae, have been counted. It is a plausible theory, that each of these is the nearer part of another zone of suns, having its remotest parts too distant for telescopes to reach. And if 25 thousand millions of suns belong to these zones, are even 25 hundred ZONES OF SYSTEMS, the whole of creation?

There is one more topic respecting the fixed stars, which may not be omitted. New stars are shining in our sky, and others which once adorned it, have disappeared, under circumstances not to be satisfactorily accounted for, but in supposing the Creator's power still employed both in kindling and extinguishing suns, in his universe.

An extract from the Surrey Lectures, of the late eminent physician Dr. Good, will give light and emphasis to this thought. What occasions the whiteness of the Galaxy? How many suns are supposed to exist in that one zone?

What hypothesis is started respecting other zones of suns? Can we set bounds to creation?

What evidence exists that new suns are created and other suns extinguished from century to century?

What distinguished authority can be quoted, in confirmation of the opinion, that stars are disappearing?

*But worlds and systems of worlds are not only perpetually creating, they are also perpetually diminishing and disappearing. It is an extraordinary fact, that within the period of the last century, not less than thirteen stars in different constellations, none of them below the sixth magnitude, seem totally to have perished; forty to have changed their magnitude, by becoming either much larger or much smaller; and ten new stars to have supplied the place of those that are lost. Some of these changes may perhaps be accounted for by supposing a proper motion in the solar or sidereal systems, by which the relative positions of several of the heavenly bodies have varied. But this explanation, though it may apply to several of the cases, will by no means apply to all of them; in many instances it is unquestionable, that the stars themselves, the supposed habitations of other kinds or orders of intelligent beings, together with the different planets by which it is probable they were surrounded, and to which they may have given light and fructifying seasons, as the Sun gives light and fruitfulness to the Earth, have utterly vanished, and the spots which they occupied in the heavens have become blanks. What has befallen other systems will assuredly befal our own. Of the time and the manner we know nothing, but the fact is incontrovertible; it is foretold by revelation, it is inscribed in the heavens, it is felt throughout the Earth. Such is the awful and daily text; what then ought to be the comment?"

CHAPTER X.

LATITUDE AND LONGITUDE, TERRESTRIAL AND CELESTIAL.

THE humble, but interesting and useful topics of Latitude and Longitude, require to be discussed. The rotation of the Earth is on an imaginary line, called its axis, the extremities of which are called its poles. A great circle round the Earth, at an equal distance from either pole, is on that account called its Equator. Lines drawn parallel to this, on either side, are called parallels of Latitude, How is terrestrial Latitude reckoned? How terrestrial Longitude?

because Latitude is reckoned across them to the poles, one quarter of a circle, or 900. The Earth being spheroidal, or flattened at its poles, occasions the first degree of Latitude to be a trifle shorter than the next, and that, shorter than the third. A meridian is a direct line, passing from one pole to the other. Wherever that line is vertical, or directly over head, it will be mid-day when the Sun is in it. The common meridian for computing Longitude is that of Greenwich, England. Degrees of Longitude at the Equator, from the spheroidal figure of the Earth, will be a trifle longer than the first degree of Latitude. They will however diminish in their length, if computed in miles, as you approach the poles, till they terminate in a point. Terrestrial Longitude is reckoned half round the globe, or 180 degrees east and west.

In the heavens there is a great circle, where the Sun makes its apparent annual path, but which is he real orbit of the Earth around the Sun. This is called the Ecliptic; because all the eclipses occur when the Moon is near this circle, at the change, or full. It makes an angle of 23° 28" with the Equator. Imaginary lines crossing the Ecliptic at right angles, as the meridians cross the Equator, are called secondaries to the Ecliptic, and terminate in points 23° 28" from the points opposite to the poles of the Earth. These are called the poles of the Ecliptic. Here we may mark the difference between terrestrial Latitude, which is reckoned from the Equator to the poles; and celestial Latitude, which is reckoned from the Ecliptic, to the poles of the Ecliptic. When Latitude on Earth is

What is the comparative length of degrees of Latitude and Longitude? What is the Ecliptic? How is celestial Latitude reckoned?