Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: May 8, 2025
The cycles and epicycles of the Ptolemaic astronomers were imperfect hypotheses, but they were stages on which the mind could rest for a more complete examination of the celestial phenomena.
The Almagest treats of all manner of astronomical problems, but the feature of it which gained it widest celebrity was perhaps that which has to do with eccentrics and epicycles. This theory was, of course, but an elaboration of the ideas of Hipparchus; but, owing to the celebrity of the expositor, it has come to be spoken of as the theory of Ptolemy.
Earth is the masculine element, sea the feminine; and all the cycles and epicycles of organic nature have resulted from these two. It develops imagination and romance in persons who would never have been suspected of possessing either. No wonder that the sailor delights in marvelous tales. It is a terrible destroyer, but at the same time a friend that we cannot do without.
The great minds, however, which really bring the race further on its course, do not accompany it on the epicycles which it makes every time. This explains why posthumous fame is got at the expense of contemporary fame, and vice vers�. We have an instance of such an epicycle in the philosophy of Fichte and Schelling, crowned by Hegel's caricature of it.
The attempts of Ptolemy and others of his time to explain the retrograde motion in this way were only approximate. Let us suppose each planet to have a bar with one end centred at the earth. Ptolemy supposed the centres of the epicycles of Mercury and Venus to be on a bar passing through the sun, and to be between the earth and the sun.
Normals are treated, not in connexion with tangents, but as minimum or maximum straight lines drawn to the curves from different points or classes of points. Certain propositions of great difficulty enable us to deduce quite easily the Cartesian equations to the evolutes of the three conics. He was also a master of the theory of epicycles and eccentrics.
As has been already stated, his successor, Tycho Brahe, supported the same use of epicycles and excentrics as Copernicus, though he held the earth to be fixed.
The geocentric system of astronomy, with its eccentrics and its epicycles, was an hypothesis utterly at variance with fact, which nevertheless did great things for the advancement of astronomical knowledge. Kepler was the wildest of guessers.
Subsequently to Hipparchus, we find the astronomers Geminus and Cleomedes; their fame, however, is totally eclipsed by that of Ptolemy, A.D. 138, the author of the great work "Syntaxis," or the mathematical construction of the heavens a work fully deserving the epithet which has been bestowed upon it, "a noble exposition of the mathematical theory of epicycles and eccentrics."
"The reduction of the motions of the sun, moon, and five planets to circular orbits, as was done by Hipparchus, implies deep concentrated thought and scientific abstraction. The theory of eccentrics and epicycles accomplished the end of explaining all the known phenomena. Induc. But I will not here enumerate the few discoveries which were made by the Alexandrian school.
Word Of The Day
Others Looking