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when the sun and moon, in relation to the earth, or some parts of it, become exactly concentric-that is, the centre of the moon and of the sun are in an exactly right line from the eye of the spectator. As the disc of the moon presents a smaller surface to the eye than that of the sun, the uncovered portion of the sun's disc exhibits a bright ring of a breadth equal to the excess of the sun's semi-diameter over that of the moon. One distinct view of an appearance so rare, curious and beautiful, would be worth the most persevering efforts, and once enjoyed could never be forgotten. There is, however, a sense of disaster, privation and calamity connected with an eclipse, more especially of the sun-the animal creation are troubled by it, the lurid dimness seems characteristic of calamity, and the event appears a momentary experience of the dismal loss that would be sustained by the total and lasting extinction of the bright lights of heaven.

The occultations of stars or planets behind the disc of the moon, as she rolls along on her course and intercepts our view of them as she passes, are appearances anxiously watched for by astronomers, as affording the most favourable opportunities for taking angles, and verifying observations and measurements. They form one of the innumerable proofs which may be presented to the naked eye, and made perfectly intelligible to the understanding incapable of scientific processes, that the system of the universe is correctly exhibited, and the motions of the heavenly bodies. accurately traced by modern astronomy.

The beauty, changes, and splendour of the moon attracted the earliest attention of men. They were regarded as even more surprising and curious than those of the sun. Besides this, occurring in the night when all the starry hosts added their wonder and beauty to the scene, and when silence invited to contemplation, to observe and comprehend the phases of the moon was, perhaps, the very first effort of simple and infant science. Hence, all nations are found to have computed time by the moon before they advanced to the more lengthened and complex measurement by the sun. The eastern patriarch watched for the new moon to regulate his worship, or to determine the transactions of life; and

the roving red man of the North American woods would inform the inquirer that it was so many moons since he slew his enemy, or buried his father. As science advanced to maturity, still the moon, its changes, its eclipses, its conjunctions, capable of being observed, verified, and understood with more ease and certainty than those of any other heavenly body, have been used as the basis of other discoveries. It has become the alphabet of astronomy, the key to unlock the treasures of wonder and glory spread out in infinite space, which, but for the first step towards their comprehension furnished by this beau tiful orb, could have been, if known at all, learned with far more difficulty, and much less clearness and certainty. In all sciences and departments of knowledge there must be some simpler beginnings, some rudiments which having been acquired, open the way for further attainment and progress. Thus only can the feeble mind of man advance in the investigation of nature, and the enlargement of his knowledge. The moon seems let down from the higher heavens to perform its various cycles and changes under our nearer inspection, and to serve as the first step by which to ascend to sublimer discoveries and more ample knowledge. It is beyond doubt, that did we not possess the advantage of the nearness and numerous changes of the moon to assist our progress in astronomical knowledge, the observation of the other heavenly bodies would have been much more difficult, and the acquaintance we might have gained of them much less certain and satisfactory. Algernon Wells.

LESSON LVIII.—WEDNESDAY.

HOPE.

Unfading Hope! when life's last embers burn,
When soul to soul, and dust to dust return!
Heaven to thy charge resigns the awful hour!
Oh! then, thy kingdom comes! Immortal Power!
What though each spark of earth-born rapture fly
The quivering lip, pale cheek, and closing eye!
Bright to the soul thy seraph hands convey
The morning dream of life's eternal day—

Then, then, the triumph and the trance begin,
And all the phoenix-spirit burns within!

Oh! deep enchanting prelude to repose,
The dawn of bliss, the twilight of our woes!
Yet half I hear the panting spirit sigh,
It is a dread and awful thing to die!
Mysterious worlds, untravell'd by the sun!
Where Time's far-wandering tide has never run,
From your unfathom'd shades, and viewless spheres,
A warning comes, unheard by other ears.

'Tis Heaven's commanding trumpet, long and loud,
Like Sinai's thunder, pealing from the cloud!
While nature hears, with terror-mingled trust,
The shock that hurls her fabric to the dust;
And, like the trembling Hebrew, when he trod
The roaring waves, and call'd upon his God,
With mortal terrors clouds immortal bliss,
And shrieks, and hovers o'er the dark abyss!
Daughter of faith, awake, arise, illume
The dread unknown, the chaos of the tomb;
Melt, and dispel, ye spectre-doubts, that roll
Cimmerian darkness o'er the parting soul!
Fly, like the moon-eyed herald of Dismay,
Chased on his night-steed by the star of day!
The strife is o'er-the pangs of nature close,
And life's last rapture triumphs o'er her woes.
Hark! as the spirit eyes, with eager gaze,
The noon of Heaven undazzled by the blaze,
On heavenly winds that waft her to the sky,
Float the sweet tones of star-born melody;
Wild as that hallow'd anthem sent to hail
Bethlehem's shepherds in the lonely vale,
When Jordan hush'd his waves, and midnight still
Watch'd on the holy towers of Zion hill!-Campbell.

LESSON LIX.-THURSDAY.

THE TIDES.

Few natural phenomena will bear comparison with the daily tides, those majestic, constant, regulated motions of the

immense oceans which cover so large a surface of our planet. Few scenes can present to our senses and our minds so striking an instance of the Creator's power over the material elements in their minutest particles, in their hugest masses, or of their strict subjugation to laws by which all their motions and properties are invariably directed. It is only the waters of the immense ocean which, under various appellations and with partial obstructions, extends from the northern to the southern pole, and spreads itself in breadths varied by the interposition of continents over almost boundless tracts, that obey the law of attraction in a daily ebb and flow twice repeated. Lakes have no tides, owing to their dimensions being so small that the moon's attraction is equal to every part, and does not therefore disturb the equilibrium of their waters. Some narrow seas also, as the Mediterranean and the Baltic, undergo very trifling changes of level for the same reason, and because their entrances are so contracted that they cannot receive a sufficient efflux from the tidal waves of the outlying oceans sensibly to raise their surfaces.

"Raised by the moon and modified by the sun, the area of the ocean is elevated into great tidal waves, which keep time with the attractions of these luminaries at each return to the upper and lower meridian. The water under the moon is drawn from the earth by her attraction, at the same time that she draws the earth from the water diametrically opposite to her, in both cases producing a tide of nearly equal height. The height to which the tides rise depends upon the relative positions of the sun and moon, upon their declination and distance from the earth, but much more upon local circumstances. The spring tides happen at new and full moon, consequently twice in each lunar month, because in both cases the sun and moon are in the same meridian; for when the moon is new they are in conjunction, and when she is full they are in opposition, and in each of these positions their attraction is combined to raise the water to its greatest height; while, on the contrary, the neap or lowest tides happen when the moon is in quadrature, or 90° distant from the sun, for then they counteract each other's attraction to a certain degree.

"The tides ordinarily happen twice in twenty-four hours, because the rotation of the globe brings the same point of the ocean twice under the meridian of the moon; but peculiar local circumstances sometimes affect the tides, so as to produce only one tide in twenty-four hours, while on the other hand there have been known three and even four tides in the same space of time.

In

"As the earth revolves, a succession of tides follow one another, and are diffused over the Pacific, Indian, and Atlantic oceans, giving birth to the tides which wash the shores of the vast continents and islands which rise above their surfaces; but in what manner these marginal tides branch off from the parent wave, science has not yet determined. the Atlantic, the marginal wave travels towards the north, and impinges upon the coasts of North America, and of Europe. In the Indian ocean it also pursues a northerly course, and finally washes the shores of Hindostan, the bay of Bengal, and the Arabian gulf; while in the Pacific, on the contrary, the waves diverge from the equator towards the poles-but in all they partake also of the westerly course of the moon."*

It is unnecessary to enlarge on the majestic scene of a rising tide, or the exact regularity of its advance to a certain line along the shore at the expected time age after age, or on its beneficial, indeed necessary influence, in preserving pure through their wide wastes those watery worlds, which, were they to stagnate, would pollute and poison the globe. But who can fail to remark the beautiful contrivance of associating with this world an attendant planet, to be not merely its lovely consort, not merely to attend on all its motions, and light and cheer it on its way, but to be the cause of phenomena so vast, constant, and salutary as the tides. We may reasonably question whether but for this provision our world would have been at all habitable; whether the ocean, now its glory, would not have been its ruin. It is now literally the salt, the purifier of the earth; but for the tides, that salt would have lost its saltness, and then with what should it have been again seasoned? It cannot fail to excite the admiring homage of every devout mind to see the Mrs. Somerville.