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النشر الإلكتروني

THE

QUARTERLY REVIEW.

ART. I.1. Observations of the Apparent Distances and Positions of Three Hundred and Eighty Double and Triple Stars, made in the years 1821, 1822, and 1823; and compared with those of other Astronomers: together with an account of such changes as appear to have taken place in them since their first Discovery. Also, a Description of a Five-feet Equatorial Instrument employed in the Observations. By J. F. W. Herschel, Esq., F.R.S., and James South, Esq., F.R.S. London. 1825. pp. 424. And Phil. Trans, 1825. part iii.

2. Observations of the Apparent Distance and Positions of Four Hundred and Fifty-eight Double and Triple Stars, made in the Years 1823, 1824, and 1825; together with a Re-examination of Thirty-six Stars of the same description, the Distances and Positions of which were communicated in a former Memoir. By James South, Esq., F.R.S. London. 1826. pp. 412. And Phil. Trans. 1826. part i.

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MONG those natural sciences which have called forth the highest powers of the mind, astronomy claims for herself the most exalted place. The bodies of which it treats are of themselves calculated to prepossess us in its favour. Their vast and inconceivable magnitude, their distance almost infinite,—their uncountable number, and the rapidity and regularity of their movements, excite, even in ordinary men, the most intense curiosity, and to minds of higher birth hold out the noblest exercise for their But while our judgment thus anticipates its pleasures and its triumphs, the imagination discovers among the starry spheres a boundless field for its creative energies. Drawing its materials from our own globe,-from its variety of life and beauty, and from the condition and destiny of our species,-it perceives in every planetary body a world like our own, teeming with new forms of life, and new orders of intelligence, and regards it as the theatre of events, whose origin, whose duration, and whose final cause, must for ever be involved in impenetrable darkness. Advancing beyond our own system, it recognises in every twinkling star the central flame of new groups of planets, and pursuing its track only in one out of an infinite number of directions, it descries system beyond system, following each other in endless succession, till it returns exhausted in its strength, and bewildered amid the number, the extent, and the magnificence of its creations.

VOL. XXXVIII. NO. LXXV.

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But while astronomy thus affords to our intellectual nature a field commensurate with its highest efforts, it is fraught with no less advantage to our moral being. The other sciences may, indeed, lay claim to a similar influence, for nowhere is the hand of skill unseen, or the arrangement of benevolence unfelt; but the objects which they present to us are still those of our own sublunary world. They are often too familiar to excite admiration, too much under our power to command respect,-too deeply impressed with our own mortality to enforce the lesson which they are so well fitted to suggest. The plains which we desolate, the institutions which we overturn, and the living beings which we trample upon or destroy, are not likely to be the instruments of our moral regeneration. Among scenes, indeed, where man is the tyrant, who can expect him to be the moralist or the philosopher?

How different is it with the bodies which the astronomer contemplates! For man they were not made, and to them his utmost power cannot reach. The world which he inhabits forms but the fraction of an unit in the vast scale upon which they are moulded. It disappears even in the range of distance at which they are placed; and when seen from some of the nearest planets, it is but a dull speck in the firmament. Under this conviction the astronomer must feel his own comparative insignificance; and amidst the sublimity and grandeur of the material universe, the proudest spirit must be abased, and fitted for the reception of those nobler truths which can be impressed only on a humble and a softened heart. He, indeed, who has rightly interpreted the hand-writing of God in the heavens must be well prepared to appreciate it in the record of his revealed will.

Though the study of astronomy thus possesses peculiar claims upon our attention, the history of the science, of the steps by which it successively attained its present state of perfection, is, in another point of view, of nearly equal interest. Commencing in the earliest ages, and carried on with but little interruption to our own day, it forms the most continuous history of the progress of human reason; it exhibits to us the finest picture of the mind struggling against its own prejudices and errors, and finally surmounting the physical and moral barrier which appeared to have set a limit to its efforts; and it displays to us in the most instructive form the labours and the triumphs of men who, by the universal suffrage of ages, have been regarded as the ornaments of their species, and as the lights of the civilised world.

In order to introduce the reader to the interesting subject of the present Article, it is necessary to take a rapid survey of the different periods of astronomical discovery.

1. The first period includes the history of the science till the time of Copernicus, when the relative positions, and the general movements of the bodies which compose the planetary system, were clearly determined.

2. The second period embraces the labours of Kepler and Newton, by which the various motions of the planets and comets were reduced to one simple law, viz., the mutual tendency of all bodies to one another with a force directly proportional to their quantity of matter, and inversely proportional to the squares of their distances.

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3. The third period comprehends the labours of Clairaut, Euler, d'Alembert, Lagrange, and Laplace, and terminates with the publication of the Mécanique Céleste, a work in which the philosophy of Newton is extended to all the nicer questions which relate to the mutual action of the planetary bodies.

1. The study of the heavens was undoubtedly coeval with the existence of man, urged by the double impulse of his necessities and fears. In the genial climate, and beneath the serene sky of the east, it seems to have made considerable progress. The great convulsion in the physical world, of which the sacred writings have traced the outline, swept away along with the races of men all the records of their intellectual attainments; but some wrecks of their astronomical knowledge seem to have been preserved either by the durability of the monuments on which it had been engraved, or by the memories of those whom the desolating waters had spared. These precious relics, which time still respects, inspired the Chaldean, Indian, and Egyptian philosophers with a reverence for astronomy, and formed the epochs of the science which they restored. From Egypt it speedily passed into Greece under the form of mysteries too sacred for the ear of the vulgar, and of allegorical emblems too profound for their understanding. Here it was soon stripped of the mystical drapery in which superstition had swathed it, and the genius of that refined people presented it purified and improved in all their schools of philosophy. In the tenets of Thales, Pythagoras, and their successors, we trace some of the soundest doctrines of modern astronomy, which form a singular contrast with the reveries of solid orbits and the harmony of the celestial spheres.

Astronomy was now destined to receive in the land of its birth all the advantages of royal patronage, and that science, which Rome despised and which Athens persecuted, found shelter among the sovereigns of Alexandria. The establishment of the Alexandrian school, and the protection and cultivation of the sciences by men who had lived in war, is the most glowing passage in the history of the human mind. It is the romance, indeed, of astro

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nomy which princes should peruse, and which statesmen should engrave upon their hearts. The formation of the library of Alexandria; the erection of its observatory; the invitation to his court of the philosophers of every clime; his participation in their conversation and in their labours, and the accessions which astronomy thence derived, have immortalised the name of Ptolemy Philadelphus, while they reflected over the darkness of future times a more intense light than was ever thrown by her blazing Pharos upon the shelves of her rugged shores.

Aristarchus, one of the earliest astronomers of this great school, determined that the distance of the sun was at least twenty times greater than that of the moon, and, convinced that the earth moved round the sun, he inferred from the position of the stars, when the earth was in the opposite points of its orbit, that their distance was immeasurably greater than that of the sun. These important steps in the science were pursued by Eratosthenes, whom Ptolemy Euergetes invited to his capital. With instruments erected by his patron, he found that the diameter of the sun was at least twenty-seven times greater than that of the earth; and by comparing the distance of Alexandria and Syene with the celestial arc between the zeniths of these two cities, he concluded that the circumference of the earth was twenty-five thousand stadia; a result not excessively different from the measurement of modern times. Important as these determinations were to astronomy, yet it was from his successor, Hipparchus, that the science derived the most valuable improvements. Collecting and comparing the observations of his predecessors, he resolved to repeat and to extend them. He ascertained the length of the tropical year; he discovered the equation of time; he fixed the lunar motions with great accuracy, and he determined the eccentricity and the inclination of the moon's orbit. His grand work, however, is his Catalogue of the Longitudes and Latitudes of One Thousand and Twenty-two Fixed Stars; by means of which he discovered the precession of the equinoctial points. In carrying on these inquiries, he was led to the principles and rules of spherical trigonometry, one of the most valuable branches of geometry. The leading works of this eminent astronomer perished in the flames which destroyed the Alexandrian library, but the most important of his observations have been fortunately preserved in the writings of his successors. //

The great advances which were thus made in the science were succeeded by a long interval of darkness, across which a few gleams of light were occasionally thrown. The Alexandriau school, however, still existed; and the consecrated name of Ptolemy, so indelibly associated with its origin, was destined in

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