« ПретходнаНастави »
rule. All the hordes are divided into bands, regiments, and squadrons. The officers are invested both with the civil and military administration. Over them all, preside inspectors, appointed by the Emperor. The chiefs of the principalities hoid
The Whistler phes menuspectors, ap. a general diet once every three years. The supreme administration is, however, in still higher hands: in those of the members of a Mongol tribunal, sitting at Peking, and which bears also the name of Tribunal of Foreign Affairs.
The dignity of prince is hereditary in the eldest son alone : the younger brothers are but in the throng of the poor nobility. Each prince pays to the Emperor a tribute consisting of cattle ; but this is merely as an acknowledgment of his supremacy; for he returns ten times the value of this feudal service, and ho. nours them frequently with presents of silver, silks, rich dresses, caps adorned with peacocks' feathers, &c. If there is a show of regard in these tokens of benevolence, there is probably in reality a still greater degree of fear and suspicion concealed under it. It is the same with the alliances of princesses of the imperial dynasty, with some of the chiefs of Mongolia - a system which was adopted by Alexius Comnenus, and formed the basis of the sundry degrees of parentage in the family of the Byzantine Emperor. This policy is so successful, that Mr. Timkowski is inclined to believe that the authority of the Emperor is secured by it, as the chiefs, on their side, are perfectly secure of the fidelity of the population intrusted to their administration. Great advantages must be offered to them, he adds, to dispose them to exchange the blessings of peace, for the chances of a revolt.
ART. 1.-Histoire de l'Astronomie au Dix-huitième Siecle,
par M. DELAMBRE. 4to. pp. 796. Publié par M. Mathieu. Paris : 1827. The History of Astronomy in the Eighteenth Century. By M. DELAMBRE. Paris : 1827.
The opening of the eighteenth century, is a memorable era in the History of Astronomy. Its whole duration was illustrated by important discoveries. At its commencement, the Philosophers of Europe found themselves in possession of superior instruments to all before known ; of improved methods of observation and of calculation : then also was given to the world, the first elements of that calculus, by which alone, the more recondite actions of bodies upon each other can be detected. These new instruments of discovery, were throughout the whole course of this century, applied to the utmost advantage, by skilful observers, accurate calculators, and profound analysts. The examination of the steps, by which the present high state of astronomical knowledge has been reached, is one of the utmost interest; we have in consequence been led to expect this posthumous work of Delambre with much anxiety. In perusing it, our anticipations have been fully realized; it is, in truth, one of the most valuable contribu. tions to the history of science with which we are acquainted, and well supports the reputation acquired by the author in his former works.
We shall endeavour to present to our readers, in as concise a form as possible, the more important facts detailed in the work before us. In order, however, to render our abridgment more intelVOL. III. —NO. 6,
ligible, we shall premise an account of the state which astronomical knowledge had attained at the close of the seventeenth centu. ry, compiled from a former work of the same author,-his Histoire de l'Astronomie Moderne.
The origin of Astronomy is hidden from us in the most remote ages of antiquity. Man became an observer as soon as he turned his eyes to the heavens ; and successive observations, gradually increasing in accuracy, and handed down by tradition from age to age, have been the basis of the information we now possess. But even the embryo of that accuracy of knowledge, and of that exactness of observation, which are the pride of modern astronomy, cannot be traced back much beyond the beginning of the century preceding that whose history is before us. Previous to this epoch, the methods, and instruments of observation, were rude and imperfect; the means of calculation, laborious and difficult. If, then, we are to look to the earliest ages of man's history for the rise of this science, we are to seek for the origin of all that is valuable in theory, as late as the sixteenth century; and for all that is correct and definite as knowledge, to the celebrated and immortal names that have embellished the eighteenth of our era.
The visions of fanciful writers have discovered, in the astronomy of the Greeks, whence we derive the little that can be called valuable, that has come down to us from the ancients, the fragments and imperfect remains of a more complete system, existing in some more civilized and remote nation. From this fancied people, they conceive, that not only did the Greeks derive what they knew of astronomy, but that it was the common source of that of the Hindoos and Chinese. Delambre, in his former works, -the histories of the astronomy of the ancients, and of the middle age, has effectually dispersed this splendid vision. He has in them conclusively shown, that the astronomy of Ptolemy is in fact that of the Asiatic nations, who, so far from giving any thing to the Greeks, or from having drawn with them from a common spring of knowledge, are in truth their scholars and imitators. Wherever, indeed, we apply the test of real science to these systems of astronomy and methods of calculation, which pretend to so lofty and remote an origin, we find at every step the traces of Ptolemy and Hipparchus ; their astronomy is not only the concentration of the discoveries of the Greeks, but the basis of that of the Arabs, the Persians, the Tartars, the Hindoos, and the Chinese, as well as of that known by the Europeans previous to the time of Copernicus.
In all these systems, we find the Earth placed immovable in the centre of the Universe, and of all the planetary motions. By means of improbable hypotheses, all these nations are enabled, in the words of Ptolemy, "to save the appearances.” They all are able to predict phenomena, and the position of bodies, within a few
degrees of the truth, and appear never to have discovered these hypotheses to be erroneous, or at least to have suspected that the mistake arose from a fundamental defect in the system itself.
The first astronomer who appears to have entertained any doubt of the truth of the hypotheses of Ptolemy, is Alphonso, king of Castile. But so far from making any valuable use of the doubt that arose in his mind, he contented himself with saying, that, “had he been called to the council of the deity when the Universe was created, he could have ordered it to greater advan
In ages more remote than those of Ptolemy, we are told, that some Grecian philosophers placed Fire in the centre of the Universe, and made the earth turn around the sun in the
space year, and on its own axis in twenty-four hours. Others, less bold, had ascribed to the earth only the latter of the two motions, and left to the sun his annual motion. But we find these ideas in no work on astronomy, nor in the pages of any geometer. Ptolemy hardly deigns to notice them ; he intimates indeed, that, to ascribe to the earth a motion of rotation, would facilitate the explanation of some phenomena; but all the rest appeared to him, too absurd to merit a serious refutation.
It is to the school of Pythagoras that the ideas of the motion of the earth are usually attributed; and this opinion has derived strength from the acts of Copernicus himself. This distinguished, and we must say original, inventor of the system we now know to be true, aware of the prejudices he was about to encounter, endeavoured to support himself, against the authority of the schools, and the dicta of Ptolemy, by the quotation of opposite opinions, from ancients of equal authority. But these opinions are so vague, that although they might in that age of darkness serve as a support to a new hypothesis, they could not have answered in any degree as a foundation on which to build it. Archimedes indeed informs us, that Aristarchus deviated from the received opinion of the age, and supposed the earth to revolve around the sun in a circle of a radius equal to that usually ascribed to the whole celestial sphere; but he takes care to show that he is of a different opinion; and when he constructed his celebrated Planetarium, he made the earth the centre of all the motions of the other bodies of the Universe. * Plutarch informs us, that the idea of Aristarchus was with him purely conjectural, but that it had received demonstrative evidence from Šeleucus; but this demonstration has not been handed down to us, nor indeed is it possible that the knowledge of the time could have furnished a correct one. Seneca says, that it is important to inquire, whether the heavens or the
* See Cicero “ de Republica.”
earth were immovable ; but this inquiry, so important in his view, receives no farther notice from him.
The Greeks were an acute and lively people; fond of argument and metaphysical discussion. Their sects of philosophers were divided on every possible question. It was sufficient that one school should profess any given doctrine, for it to find opposers among the neighbouring sects. The most ancient philosophers, no doubt held, in conformity with appearances, that the earth was the centre of the universe, and that the sun, by its various motions, caused the alternations of day and night, and the vicissitudes of the seasons. They were then content to imagine a mechanism by which the several less obvious and collateral phenomena might be produced. Some, of the school of Pythagoras, or perhaps that philosopher himself, for the mere sake of contradiction, placed the sun in the centre of the system, and launched the earth into the ecliptic, there to perform an annual revolution. But in what did the merit of this consist, as compared with the system of their opponents? They alleged, as their sole and simple reason, that the sun was the most noble of al bodies. To this it might have been replied, with equal force, and more of popularity, that man is the most important of beings, that all has been created for his use, that it was fit that his abode should be fixed and permanent, and proper that the heavenly bodies should turn around him to give him light, and afford him vital heat. Such reasons, if in truth no better than those of the Pythagoreans, carried with them at least more of probability, particularly as they are consistent with the impressions derived from our senses. And what motive can we suppose the people of Greece would have to reject the apparent evidence of their senses, and believe in the motion of the earth? They had not observed a single phenomenon which could not be accounted for on the other hypothesis ; even the stations and retrogradations of the planets had been explained by means of it. They were ignorant of the great size and distance of the heavenly bodies ; the improbability of their being created especially and solely for the use of the inhabitants of our carth, could not therefore have occurred to them. In truth, it is almost within our own days, that the astronomic phenomenon, which shows conclusively the annual motion of the earth, has been detected ; and the truth of its diurnal motion of rotation was supported by no known fact, not equally applicable to the hypothesis of Ptolemy, before the latter end of the seventeenth century.
Until these dates, and before the discovery of the universal influence of gravitation, even the most determined of the followers of Copernicus, were obliged to resort, in defending his theory, to the evidence of probabilities alone. They were compelled to sustain their opinion by exhibiting the simplicity of the views of