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system were even entertained, but upon inadequate grounds, and amidst a variety of theoretical systems; and it was not until the year 150 B.C. that Eratosthenes, the librarian of Alexandria, measured an arc of the meridian, and computed the earth's circumference. Among the remarkable circumstances of the interesting progress of this vast and sublime development of genius and observation, thus in (as it were) the first stage of its elevation, two are specially to be observed, for their essential connexion with the history both of astronomy and of human reason. The one, had we time and space, would lead us into the history of astrology

a wonderful combination of the great and little properties of human

nature, under the towering shadows of which, the science of observation was preserved and fostered in its growth. The other is the beautiful application of an expedient still employed in natural philosophy, for the same purpose of imbodying and subjecting to computation the results of experience. A system purely empirical combined the observed phenomena of the known bodies of the solar system, in Such a manner, that being framed so as to include all that could be observed of their motions, it was thus not only adapted for the purpose of computation within those limits, but also served to lead to a closer and more precise measure of phenomena, which, without the reference to some standard system, might easily escape the minute observation necessary for the detection of small quantities of motion or changes of position, such as might lead to further corrections. Of such a nature was the hypothesis by which Apollonius first attempted to solve the seemingly anomalous motions of the planets. This curious system, which was the faith of Europe for fourteen centuries, is worth the reader's attention, and, without any certainty that we can render it popularly intelligible, we shall here attempt to describe it.

In conformity with the universal tendency to explain phenomena by assumptions which seem the most natural, it first began to be the received opinion that the sun and planets moved in circular paths round the earth, which was supposed to be fixed in the centre. The parallel paths and circular apparent motions of the phenomena of the heavens, suggested the notion of a crystalline sphere, in which the multitude of the stars was set, and which revolved with a solemn continuity round its terrestrial centre. The observation of the unequal and contrary apparent motions of the moon and planets extended the theory, and separate spheres of hollow crystalline were devised, to account for these diverse phenomena. It was to these vast concaves, thus spinning round with complicated but harmonious times and movements, that some Eastern poets have attributed a sublime and eternal harmony, unheard in this low world, but heard we should presume, in the

"Starry mansion of Jove's court."

Such was the first rude and simple outline of the system as adopted by Aristotle and old Eudoxus. Closer and further observation, in the course of time, detected phenomena inconsistent with such a system, and for a time astronomers were content to observe. In proportion to the multiplication of phenomena, conjecture became more timid, and system more difficult. At last, the ingenuity of the geometer Apollonius contrived the first form of a theory which explained the great irregularities of those planetary motions, which most readers now understand to be the combined result of the separate motions of the earth and planets. Instead of a concave sphere having its centre of motion in the earth, Apollonius conceived each of the planets to be carried round on the circumference of a circle, which was itself carried round upon another circle, the circumference of which was the path of its centre. By this ingenious device, the planetary phenomena now so well known by the terms direct, retrograde, and stationary, seemed to be explained. The appearance of a new star, and the long and laborious course of observation into which it led Hipparchus, who undertook in the true spirit of inductive philosophy to catalogue the stars, conducted this great astronomer to the discovery of the precession of the equinoxes.

A new circle, on which the sun was moved, according to the law already explained, reduced this phenomenon to the same convenient system. To this great geometer is attributed the invention of the method of latitude and longitude, by which the position of places on the earth is ascertained: the invention of spherical trigonometry is said also to be among his discoveries.* Of these, however, the most considerable portion were lost, and the remains appear only to be known by their preservation in the Almagest of Ptolemy. Three hundred years after the great philosophers already mentioned, their system, with the addition of whatever observation had added in the interval, came into the hands of Ptolemy, whose name it has ever since borne. This great man, not undeservedly, called prince of astronomers by the ancients, may be described as the Laplace of old astronomy: he collected, combined, and completed the results of observation, and reduced the real and theoretical knowledge of his predecessor into an improved, corrected, and augmented theory. A system of empirical knowledge, even then displaying a grand and sublime aspect of the vast capability of human reason, though now chiefly valuable for its connexion with the faith, the superstition, and poetical remains of other times; unless to those who can appreciate its value as a magnificent ruin of ancient philosophy, more instructive and more sublime than Thebes or Palmyra,

Of this system, of which we have forborne to attempt a detailed description, (which would only embarrass the reader who does not already understand it,) one of the effects was, to render permanent the errors which it contained, by the seeming precision with which it explained and calculated the known phenomena of nature. The broad intelligence of Hipparchus and Ptolemy were probably not deceived: they understood the nature of the process too well: they were aware that a theory which comprised, in its first elements, the whole visible phenomena, as well as the rates of movement and times of occurrence, must necessarily, within certain limits, appear to reproduce them as results of calculation. But the very fact that a known succession of phenomena could be thus deduced from a theory, seemed to offer an unanswerable verification of its truth, to a long succession of mindless

* Laplace Systeme du Monde.

ages, whose broken recollections of ancient knowledge were simply the dreams of superstition.

A long period of ignorance followed, in which all science was lost, and human reason was engrossed in devising sophisms and subtle errors. Science, lost in Europe, found refuge in the East; and about the end of the seventh century began to be cultivated with extraordinary zeal and success by the Arabians, who invented algebra, and are also supposed to have invented trigonometry. They translated a vast number of works of Greek science, and among the rest the Almagest of Ptolemy, about the beginning of the ninth century.

At the revival of learning in Europe, astronomy, which had always more or less occupied the schools, from its connexion with astrology, as well as its essential combination with the adjustments of the calendar, began earliest to occupy attention. Among the works of science brought from Arabia, the Almagest of Ptolemy was obtained, and translated into Latin, by the patronage of Frederick III., in 1230. From this, a quick succession of astronomers and geographers began to construct anew the science of antiquity.

The progress of geographical knowledge had been far more retarded and uncertain. Being chiefly dependent on detailed and local research, it was the less likely to be advanced beyond the narrow limits occupied by civilized nations. Notwithstanding the measurement of Eratosthenes, which is supposed to have been not far from correctness, the geographers who follow for many ages were farther from any approach to the truth. The maps of various geographers of the middle ages, are still extant, to prove how restricted were the bounds of the known world; the farther extremities of Europe, Asia, and Africa, were shut out from all but conjecture: America was yet undreamed of. The knowledge which actually existed was more due to commerce and conquest than to science; and the march of the army, or the station of the caravan, were more to be relied on than the chart of science. In England, the first idea of a topographical survey originated in the distribution of the Saxon lands by the Norman conqueror, and gave rise to the celebrated compilation called Doomsday Book. The crusades gave some impulse to the advance of topographical knowledge. The travels of Marco Polo extended geography widely into the East. A long and improving course of maritime discovery set in, and as navigation became cultivated, far less obstructed voyages of discovery soon afforded more correct and extended notions of the compass and form of the old world. Still, however, the condition of geographical knowledge considered as a science, remained in the state in which it was left by Ptolemy.

It is in this state of the science that the great standard work of Sacrobosco finds its place. It held the schools for the following 300 years, went through numerous translations, and has been published with a commentary by Clavius. It might still have held its ground, and Sacrobosco his fame, but for the revolutions in science which the sixteenth century produced. A succession of new intellects broke from the regenerated schools of antiquity. The cycle of a long decline of scientific genius seemed to have rolled back into its renovation of youthful vigour,—the geometry of Archimedes, Apollonius, and Euclid, seemed to conduct Copernicus, Kepler and Galileo back to the era cf Pythagoras. These great men discovered the inadequacy of the Ptolemaic system to account for the phenomena of the solar system. They were silenced by the despotism of ignorance; but they propagated the impulse of right reason, and the light they left never slept till it came into the school of England and the hand of Newton. Every one is aware of the main facts of the Newtonian system. But should any one who has read so far, ask the question which has been often asked—what is our security that the system of Newton is not as fallacious as the system of Ptolemy? the only answer we can give is this, that the principles of their construction are not simply different, but opposite—the one is a system devised to explain appearances, the other an undevised system, self-built, from discovered truth—the one is a theory, the other a collection of accurately ascertained facts—the one was intentionally assumed to represent what meets the eye, the other studiously rejecting both assumptions and appearances, may be regarded as the laborious work of the observation of ages, slowly falling together, until a hand of power, revealed the fundamental fact which disclosed the secret system of nature. The distances, magnitudes, and motions of the system are facts, tangible to sense: the theory of gravitation rests on the most universal analogy yet discovered, and on the most varied and complex confirmation of geometrical reasoning and computation. "The terms attraction and gravity," says Mr Woodhouse, "although they seem borrowed from the language of causation, are not meant to signify any agency or mode of operation. They stand rather for a certain class of like effects, and are convenient modes of designating them."* The law of gravity is the statement of a fact. If it were to be disproved, the vast system of facts, of which it is the combining principle, still remains the same—a symmetrical collection of calculable facts, unmixed with a single inference from mere theory.

We shall hereafter have to offer a more expanded view of this subject, and a continuation of the history of the progress of these parts of knowledge.

$etcr.

FLOURISHED a. D. 1240.

Peter, an Irishman of great ability, and remarkable both as a philosopher and a theologian, went to Italy on the special invitation of Frederick II., who had at that time restored the university of Naples, and wished to have a man of his learning and acquirements, both as an example and instructor to the rising generation. He was tutor to Thomas Aquinas in philosophical studies, in the year 1240, and wrote Quodlibeta Theologica. The time and place of his death are unknown.

* Preface to Physical Astronomy.

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FLOURISHED a. D. 1270.

Thomas Hibehnicds was born in the county of Kildare, at a place called Palmerstown. He left his own country and became a fellow of the college of Sorbonne. He continued to reside for some time in Paris, and afterwards travelled into Italy. Marian of Florence writes, "That Thomas, the Irishman, flourished in the year 1270, in the convent of Aquila, in the province of Penin, now called the province of St Bernardin, and was in great reputation for his learning and piety." He continued in this monastery until his death, the period of which is unknown, and was buried there. On his deathbed, he bequeathed all the books he had written, with a variety of other manuscripts, to the college of Sorbonne, together with six pounds for the purpose of purchasing a rent to celebrate his anniversary. The necrology of Sorbonne, states that "Master Thomas of Ireland, formerly a fellow of this house, died. He compiled Manipulum Florum, and three other small tracts, which he sent to us, and bequeathed to us many other books, and six pounds in money to buy a rent to be employed in celebrating his anniversary." Ware says that the above-mentioned treatise was begun by a Franciscan friar, of the name of John Gualleis or WaUeis, and that, he dying, Thomas completed it, and gave it the title of

Flores Doctorum pene omnium, qui turn in Theologia, turn in Philosophia, hactenus Clarnerunt, lib. it.

He also wrote—

De Christiana Religione, lib. i.
De Illusionibus Daemonum, lib. i.
De Tentatione Diaboli, lib. i.
De Remediis Vitiorum, lib. i.

Ware quotes the following catalogue of his writings from the Bibliotheque of the Dominican order:—

Tabula Originalium, sive Manipulus Florum secundum ordinem alphabet extracta ex libris 36, Auctorum, edita a M. Thoma Hibernico, quondam Socio Domus Scholarium de Sorbona Parisiensis Civitatis.

Liber de tribus punctis Christianas Religionis Commendatio Theologia,

beginning "Sapientia jEdificavit fidi Domum," &c, which he explains according to the mystical, allegorical, and moral sense.

Tractatus de tribus Hierarchiis tam Angelicis quam Ecclesiasticis.

In the college of Sorbonne there is another manuscript ascribed to him, under the title of

In primam et secundum sententiarum.

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