"If this fair flower be plucked, oh, misery! oh,
Despair! what more is left me but to die?
Almighty God, with every other woe

Rather than this, thy wretched suppliant try.
If this be true, these hands the fatal blow

Shall deal, and doom me to eternity.

Mixing his plaints with bitter tears and sighs,

So to himself the grieved Orlando cries."-C. vii. s. 76.

One more extract and we take leave of Tasso for the present, although not without expressing the hope that we will soon have an American edition of Rose's translation of his great work. If it has ever been printed in this country in any form we are not aware of the fact; and the same remark will apply to Dante's Divina Commedia, Tasso's Gerusalemme, and Camoens' Lusiad. We feel certain that if handsome editions of these various chefs d'œuvre were presented to the American people, they would fully requite the publisher for his enterprise and spirit in doing so. We can assure all concerned that no better means could be adopted to improve the public taste; it would also have the effect of removing many prejudices now existing as to the comparative encouragement given to literature by republics and so-called despotisms. We would make the suggestion in particular to those spirited publishers of the Modern Athens, who are as much distinguished for their friendly and encouraging attention to the muses as they are for their general discrimination and taste as public caterers. For our own part we will do all we can to raake the American people acquainted with those sublime geniuses. We have had articles on each already, but only introductory ones. In future papers we will give copious extracts, selecting, however, those that are most characteristic, and giving our impressions of their beauties. None admire the principal British poets more than we do; or those of our own poets who have any just claim to the title. We do not discuss the merits of either as much as we do those of foreign poets, chiefly because we prefer to tell our readers something they do not know rather than what they are already familiar with, but partly because great poets are so few that they must be sought for in different countries; in the ancient as well as in the modern world.

Now to our closing extract; and where there is such a profusion of beauties of various kinds, it is difficult to make a selection. It is generally admitted that even the imagination has seldom indulged a stranger or more capricious flight than that of Astolpho to the moon in search of the

lost wits of Orlando. This we had marked as an instance of the peculiarly happy manner in which playfulness and sublimity are combined in the Furioso. The story of this curious journey embraces some sixteen stanzas of the most exquisite poetry; but a fragment of it could give no idea of the merits of the episode as a whole. We must, therefore, content ourselves with a shorter piece; although this, too, is a fragment we mean the concluding stanzas of the deseription of Rogero's combat with Rodomont, which also concludes the poem. Those who read this carefully, even in a translation, will hardly think it exaggeration to say that in describing the exploits and achievements of his heroes, as well as in the delineation of character Ariosto is inimitable:

σε Rogero at his vizor doth present

His naked poniard's point, with threatening cry
That he will slay him, save he yields, content
'To let him live, if he for grace apply.'

But Rodomont, who rather than be shent
For the least deed of shame, preferred to die,
Writhed, struggled, and with all his vigor tried
To pull Rogero down, but naught replied.

"As mastiff that below the deer-hound lies,

Fixed by the gullet fast, with holding bite,
Sorely bestirs himself and vainly tries,
With lips besmeared with foam and eyes alight,
And cannot from beneath the conqueror rise,
Who foils his foe by force, and not despite;
So vainly strives the monarch of Argier
To rise from underneath the cavalier.

"Yet Rodomont so twists and strives, he gains
The freedom of his better arm anew;

And with the right hand which his poniard strains,
For he had drawn his deadly dagger too,
Would wound Rogero underneath the reins:
But now the wary youth the error knew

Through which he might have died, by his delay

That impious Saracen forthwith to slay;

"And smiting twice or thrice his horrid front,
Raising as high as he could raise in air
His dagger, buried it in Rodomont;

And freed himself withal from further care,
Loosed from the more than icy corse, to font
Of fetid Acheron, and hell's foul repair,
The indignant spirit fled, blaspheming loud;
Erewhile on earth so haughty and so proud."

ART. II.-1. Théorie de la Lune, deduite de seul principe de l'attraction. Par M. CLAIRANT. Paris, 1842.

2. The Principia. By SIR ISAAC NEWTON. London, 1814.

3. Selenotopographische Fragmente zur genauern Kenntniss der Mondflaeche, &c. Von J. H. SCHROETER. Gottinga, 1802.

4. Fundamenta nova Investigationis orbitæ veræ quam luna perlustrat, &c. P. A. HANSEN. Gothæ, 1838.

5. Théorie du Mouvement de la Lune. Par T. MAYER. Turin, 1832.

6. Cosmos; a Sketch of a Physical Description of the Universe. By ALEXANDER VON HUMBOLT. London, 1861.

It has frequently occurred in the history of science that researches undertaken for a special purpose, although fruitless as to the end for which they were instituted, have led to unexpected and interesting results. As examples of this fact we might cite some of the most important discoveries of Bradley, Olbers and Sir William Herschel. The earliest instance, however, is that of certain astronomical observations made at Babylon more than seven centuries before the Christian era. These observations, recorded by the Chaldean priests for astrological purposes, survived the dissolution of successive empires, and, after a lapse of 2,500 years, afforded data for establishing one of the most remarkable inequalities in the motion of our satellite.

The time occupied by the moon in completing a revolution round the earth, or the interval which elapses from her leaving a fixed star till she again returns to it, is 27d. 7h: 43m. 11s. This, however, is not the period in which she passes through her series of changes. The latter, which is denominated a lunar month, or synodical period, is the time from one new moon to another, or the interval between two consecutive conjunctions with the sun. Its length is found: by observation to be 29d. 12h. 44m. 2-87s. On account, however, of the sun's disturbing influence this interval is not always precisely the same. The mean synodic period-that 8, the average length of a great number of consecutive revolutions was determined by Dr. Halley, as accurately as possible, from modern observations alone. But from the eclipses. observed at Babylon, about 720 B. C., he was enabled to ascertain the mean motion at that remote epoch; and, on comparing the ancient with the modern observations, the periodic time was found to have diminished. Again, from the

works of Albategnius, an Arabian astronomer of the ninth century, it was perceived that at the date of his observations the moon's time of revolution was less than the ancient, but greater than the modern period. Halley accordingly inferred that the mean motion had been continually accelerated from the time of the first eclipses recorded at Babylon. At the period of this discovery (1693) the longitudes of the points from which the ancient observations had been made were not accurately known; the precise value of the acceleration could not therefore be given. Subsequently, however, the situations of those places were more exactly ascertained, which enabled Dunthorne (1749) not only to verify the fact of Halley's discovery, but also to determine the quantity by which the lunar period had diminished.

This anomaly was regarded by the scientific world with extraordinary interest. During the long interval between the time of its discovery and that of its physical explanation by Laplace, in 1787, it was the subject of much learned and ingenious speculation. Of the numerous hypotheses proposed for its explanation we may instance the following:

That the mass of the sun is gradually diminished by the emission of the particles of light. The effect of such a diminution of the attractive force by which the earth is retained in its orbit, would be an increase in the length of the year. This would make the sun's apparent motion in the ecliptic slower, and consequently the moon would require less time to gain one entire revolution; in other words, the synodic month would be shortened. other conjecture was, that the earth's velocity of rotation had, from some cause, been slightly retarded; in which case the length of the day would be increased, and hence the moon's period apparently shortened.* Others supposed

An

*This hypothesis was, at one time, regarded with favor by the celebrated Rittenhouse. "We do not certainly know," he remarked, "whether that apparent acceleration of the moon's motion, which Mayer, with other great astronomers, has admitted, ought to be attributed to a real increase of velocity in the moon, or to a diminution of the earth's diurnal motion. If to the former, the destruction of this beautiful and stupendous fabric may from thence be predicted, with more certainty than from any other appearance in nature. But if to the latter, it may be prettily accounted for by Dr. Halley's ingenious hypothesis concerning the change of variations in the magnetic needle. The Doctor supposes the internal crust or shell of the earth to contain a nucleus detached from it, and that the impulse which first caused the diurnal motion was given to the external parts, and from thence in time communicated to the internal nucleus, by means of an intervening fluid, but not so as per fectly to equal the velocity of the superficial parts of the globe. Whence it

that a resisting medium diminished the moon's centrifugal force, and thus lessened its period. The insufficiency of gravity alone to account for the phenomenon was generally admitted.

A thorough investigation of this perplexing and mysterious problem was at length undertaken by the celebrated Laplace. It was well known that the orbit of the earth is an ellipse, with the sun in one of the foci; that, in consequence of the sun's disturbing influence, the mean distance and period of the moon are greater than they would be independently of such disturbance; that the solar perturbation is greatest when the earth is nearest the sun, and least when it is most remote; and, finally, that any variation in the form of the earth's orbit would affect the amount of the sun's disturbing force, and thus produce a change of some kind in the moon's periodic time. The question, therefore, which presented itself for Laplace's consideration was-Has the form of the earth's orbit been actually changing for the last three thousand years?-if so, has the variation been such as to harmonize with the observed shortening of the lunar period, and can it be shown to result as a necessary consequence from the law of universal gravitation? To test this interesting question, the amount of disturbance produced by the principal members of the system was carefully determined. The result proved that the eccentricity of the earth's orbit is slowly diminishing; that our planet's perihelion distance is therefore increasing, and the disturbance of the moon's motion by the solar attraction decreasing; that this gradual opening out of the earth's orbit has been going on for many thousands of years; and finally, that its rate is such as to account satisfactorily for the acceleration of the moon's mean motion. The great difficulty was therefore resolved, and the Newtonian law of gravitation completely vindicated.

The rate of variation of the terrestrial orbit is such that -while the major axis remains always the same-the perihelion distance increases about thirty-nine and a half miles every year; in other words, the sun annually approaches

will follow, that the external shell of the earth is still communicating motion to the internal parts, and losing motion itself proportionably. The diurnal motion must, therefore, become slower and slower, yet can never be retarded, by this cause, beyond certain limits, nor can we conceive that any inconve nience will follow."-Address delivered before the American Philosophical Society in 1775.