[One half of the earth's convex landscapes being always in light, and the other in shade, the earth's daily rotation on its own axis rolls us into and out of our own shadow, causing day and night. The earth, rolling from West to East on its own axis, it is always mid-day and midnight at opposite meridians of longitude, and an eternal sunrise and sunset at the intermediate meridians.]

VI.

One half in day and summer light
The eternal changeful seasons turn;
One half in shade and winter night

The varying landscapes freeze and burn.

[The preceding stanza illustrates the relations of the sun's light, caused by the earth's daily motion on its poles. This stanza refers to those changes which result from the earth's annual motion round the sun, and are caused by the inclination of the earth's polar axis to the plane of its annual path in its orbit, (the Ecliptic.) As only one half of the earth's convex landscapes can be in sunlight, it is obvious that day and night, and summer and winter, in all their varieties, must alternate constantly in the alternate hemispheres. As on a given parallel of latitude, that is on a line drawn East and West round the earth, mid-day, sunset, midnight and sunrise are always present-so of a line drawn North and South round the earth-one half must be in sunlight, and the other in shade. There can be but one point where the sunlight falls vertically from the zenith, on the earth's surface. About six thousand miles, or one fourth of the earth's convex, from this vertical point, West-it is sunrise-six thousand East, it is sunset-and also six thousand miles North or South from this vertical ray, the sunlight must be falling parallel with the earth's surface, both in the arctic and antarctic latitudes.]

VII.

Myriads of sunbeams interweave their light,
Throughout the boundless distance of the sky;
And gem the spangled canopy of night,

Where'er the wanderer turns his thoughtful eye.

VIII.

The furthest starbeam's telescopic flight,
Direct, unerring from its centre runs ;
Threads the vast maze of inter-radiant light
Athwart the day-source of a thousand suns,

IX.

On every side each distant sun displays,
Across the daylight of each other sun,
Its radiant sphere of still expanding rays,
Widening and widening e'en since time begun.

X.

The feeblest starbeam in its furthest flight,
Across the dazzling dayfires of the sky,
Truly reveals its centre and its source

Unscorched and changeless to the gazer's eye.

[Stars, single in appearance to the naked eye, or with telescopes of smaller power, when you use telescopes of greater power, are continually discovered to be double stars; that is, two stars so nearly in the same line of vision, star behind star, as only to be seen separately by the use of lenses of increased power. This remark may also apply to those larger clusters of stars which appear to the eye as nebulæ, or bright cloud-like spots of white light, but which are ascertained to be stars so nearly in the same line of vision as to appear like aggregations of stars.

[Herschel's telescopes reveal star behind star, constellation beyond constellation, clusters and clouds of stars appearing such from their immense distance, but in reality all suns. Let us consider the most distant of allthe light of this most distant star, radiating through the maze of inter-radiating light of every other star, and through and across the very daylight source of many of them, reaches the eye unaltered, and if the idea of heat is inseparable from sunlight, "unscorched."]

XI.

E'en when the student swings great Herschel's lens,
Measuring in mighty tracts concentric space;

Each telescopic sun his vision kens

Further and feebler has its certain place.

XII.

In Cancer, or in Leo, as we roll,

One starry baldric fills the midnight air;
Whether we view the Zodiac or the Pole,

The constellated suns of space are there.

XIII.

As fades a stone's splash in the waves around,

Though suns may darken at light's starting place; While ages roll, and cycles wheel their bound,

Light speeds, centrifugal, its onward race.

[This alludes to the alleged disappearance of certain stars, as the lost Pleiad.]

XIV.

Heaven's vast machine defies the optician's art,
Naught but Omniscience its depths may scan.
What man may know is but a little part,
All unrevealed to him the glorious plan.

XV.

Author of All! Almighty, yet unseen,
Wondrous, surpassing wonder Thou must be,
Thou veil'st thyself beyond the starry scene,
The light thou mad'st reveals thy works, not thee.

XVI.

Thy Omnipresence shrouds itself in light,

Where its bright rays illume the furthest sky;
The tiny shadow of Earth's little night

Hides nothing from thine ever seeing eye.

[The shadow of a planet, as of Venus, or of the earth, is its shadow, which always exists on the side from the sun, and our rolling into and out of which causes day and night to us. It obstructs the whole sunlight no more than a raven's wing in the furthest horizon.

[The same laws of radiation from each point to every other point-the same wonderful inter-radiations-are true of reflected light. Let us suppose a million of observers on a monntain side—above them the Heavens -before them a rich and varied landscape. Each observer, if he looks upward, receives on the expanse of the nerves of vision a daguerreotype of the constellations. If he looks forward and around, he has a changing daguerreotype of the landscapes. The daguerreotype of the constellations may, it is true, be obscured by the daylight of our own star; but it is not the less certainly there.

[Provide each observer with telescopes of great power; each and all can

now analyze the celestial area, and fix upon any one of the telescopic stars. Its feeble light is present to all.

[Each and all in concert can next analyze the landscape, and reduce its vast variety to distinct vision. They can, with a common portable engineer's telescope, see the same man forty miles distant. The eye is the most delicate and accurate of optical instruments. The telescope lengthens the darkened vestibule of its camera-obscura like chamber, and thus more effectively prevents the interference of lateral light. The most complex perspective, the most exquisite foliage of the distant landscape, which would be perceptible only by a telescope of a thousand powers, are unquestionably pictured with perfect exactness upon the eye of the rudest observer. The rapidly changing, yet invariably accurate inter-pencillings of the rays of light, falling in straight lines, as Newton considered them, appear sufficiently incredible, without adding all the zig-zag confusion which the undulatory theory superadds to the phenomena of vision.]

The entire co-instantaneous action of the laws of light and of gravitation, existing in the expanse of the Heavens, the phenomena of day and night and of the seasons, the whole vegetable and animal world in all climates and latitudes, and one thousand millions of our fellow creatures all cotemporaneously existing, as light and shadow succeed each other, in pauseless succession, on the revolving globe, is too vast an idea for immediate conception. It is a subject of deliberate study; and to make this study more easy and popular, is the design of the present pages.

A vivid and adequate idea of our own planet is, we conceive, an indispensable introductory to the comprehensive conception of the vast scene of the Heavens around us. The most distinguished of astronomers, Kepler, and Newton, and Laplace, have incontestably demonstrated the proportions of our earth to the solar system to be so exceedingly small that at the larger and more distant planets, of which our sun is the centre, the earth would be absolutely invisible to the human eye. Jupiter is 1,400 times the bulk of the earth, and the visibility of the earth at Jupiter is, of course, in proportion; it is that of an orb of the bulk of Jupiter, as it appears to us.

The greatest mathematicians-the most distinguished

adepts in the laws of proportion and the relations of numbers, and in those abstract symbols and modes of calculation which establish, on irrefutable data, the most amazing results in the vastness of the universe around us, we are inclined to believe, from the narrowness of the human intellect, have hitherto seldom combined, with their profound contemplations of the Heavens, an adequate conception of their native planet

"One science only does one genius fit,
So vast is art, so narrow human wit."

Or at least they have not been so happy in their illustrations as to leave nothing to be desired.

Having thus briefly opened, we shall defer this portion of our subject and the further important illustrations which belong to and arise from its consideration, till after several other chapters, which, perhaps, are essential to the scope of the co-existent Drama of Nature.

CHAPTER VI.

A DAY-THE DIURNAL REVOLUTION OF THE EARTH ON ITS AXIS.

We are living upon the Earth, one of the eleven planets which revolve round our Sun. Although the Earth is very small in comparison with some others of the planets, being as we have noticed in the preceding chapter, only 1400 of the bulk of Jupiter, and is such a mere speck in comparison with the spaces of the Solar system as to be receiving only about one twenty-two hundred and fifty six millionth of the whole Sun's light; yet, compared with our feeble means of observing and exploring it, it is an orb of immense magnitude, whose parts have not yet been entirely explored, and whose varied productions seem almost infinite, so as afford a field of investigation exhaustless to human industry. Even if, for the sake of better observation,