While at work on the Rudolphine tables he used the old epicycles and deferents and excentrics, but he could not make theory agree with observation.
Copernicus had introduced two epicycles on the lunar orbit in the hope of obtaining a better accordance between theory and observation; and he was not too ambitious, as his desire was to get the tables accurate to ten minutes.
It is true that neither the Pythagorean nor the Egypto-Tychonic system required epicyclesfor explaining retrograde motion, as the Ptolemaic theory did.
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.
The major planets were supposed to revolve in the deferent round the earth in their own periodic times, and in their epicycles once in a year.
We may look upon these epicycles of Apollonius, and the excentric of Hipparchus, as the responses of these astronomers to the demand of Plato for uniform circular motions.
In now taking leave of the system of epicycles let it be remarked that it has been held up to ridicule more than it deserves.
The centres of theepicycles of Mars, Jupiter, and Saturn were supposed to be further away than the sun.
Mercury and Venus were supposed to revolve in their epicycles in their own periodic times and in the deferent round the earth in a year.
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.
He adopted the epicycles and deferents which had been used by Apollonius and others to explain the retrograde motions of the planets.
It did not occur to Ptolemy to place the centres of the epicycles of Mercury and Venus at the sun, and to extend the same system to the major planets.
The epicycles represented nothing more nor less than the first terms in the Fourier series, which in the last century has become a basis of such calculations, both in astronomy and physics generally.
A system of eccentrics and epicycles has been elaborated which serves to explain the apparent motions of the heavenly bodies in a manner that may be called scientific even though it is based, as we now know, upon a false hypothesis.
That is to say, these astronomers probably did not conceive either theepicycles or the greater spheres as constituting actual solid substances.
As new irregularities of motion of the sun, moon, and planetary bodies were pointed out, new epicycles were invented.
In other words, the theory of epicycles will account for all the facts of the observed motions of all the heavenly bodies, but in so doing it fills the universe with a most bewildering network of intersecting circles.
In proportion as observation elicited fresh facts, contradictory to these representations, other epicycles and eccentrics were added, involving additional confusion.
To him also must be attributed the establishment of the theory of epicycles and eccentrics, a geometrical conception for the purpose of resolving the apparent motions of the heavenly bodies, on the principle of circular movement.
But no planet's motion could be represented by uniform motion in a single circle, and Copernicus had still to make use of systems of epicycles to account for the deviations from regularity in the planetary motions round the Sun.
The chief of the Ptolemaic epicycles were done away with, and all the planets moved continuously in the same direction round the Sun.
But he combined with this determination a theory of epicycles and eccentrics which modern astronomy discards.
The ingenious epicycles of Ptolemy prepared the way for the elliptic orbits and laws of Kepler, which in turn conducted Newton to the discovery of the law of gravitation,--the grandest scientific discovery in the annals of our race.
The theories of eccentrics andepicycles accomplished the end of explaining all the known phenomena.
Those who want an example of the general scheme of epicycles taken from the history of art need only look at the School of Sculpture which flourished in the last century under Bernini, and especially at its further cultivation in France.
The false paths the human race soon follows after any important progress has been made represent the epicycles in the Ptolemaic system; after passing through any one of them the planet is just where it was before it entered it.
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.
To explain the other phenomena, such as the stations and retrocessions of the planets, recourse was again had to the epicycles or deferred eccentric circles.
Thus the passage condemned by Luther, in which the resort by theologians to the doctrine of 'original sin' was compared to the invention of epicycles by mediaeval astronomers, was retained in all essential particulars without modification.
Luther was honestly and naturally shocked when he found Erasmus hinting that the doctrine of 'original sin' was in some measure analogous to the epicycles of the astrologer.
The next advance was made by Kepler, who overthrew at one blow all the excentrics and epicycles of the ancients, when by his laborious calculations he proved the ellipticity of the orbit of Mars.
But he did not give up the excentrics and epicycles for the explanation of the irregular motions of the planets, and certain imaginary variations in the precession of the equinoxes and the obliquity of the ecliptic.
But the great minds, who really bring the race further on its course do not accompany it on the epicycles it makes from time to time.
The false paths on which humanity usually enters after every important advance are like theepicycles in the Ptolemaic system, and after passing through one of them, the world is just where it was before it entered it.
Tycho hath feigned I know not how many subdivisions of epicycles in epicycles, &c.
His thirty-four circles or epicycles comprised four for the earth, three for the moon, seven for Mercury (on account of his highly eccentric orbit) and five each for the other planets.
They even supposed the moon to have one, perhaps two epicycles and we shall find this notion reflected in Chaucer.
Chaucer was undoubtedly familiar with the irregularities of the planetary movements, and with the theory of epicycles by which these irregular movements were in his day explained, although it is not from his poetry that we can learn the fact.
Later investigators complicated the system by adding further secondary imaginary planets, revolving in Ptolemy's epicycles and with the actual planets attached to additional corresponding epicycles.
By combinations of epicyclesand eccentrics the mediaeval astronomers contrived to reduce the number of principal spheres to one for each planet, the arrangement we find in Dante.
If need were, this type of hypothesis could be further complicated by imagining any number of such epicycles within epicycles.
Epicycles and eccentrics, Hipparchus's theory of, i.
Its defenders had to go on adding one piece of machinery after another, as new classes of facts came into view, till it became more complex and unmechanical than the theory of epicycles and eccentrics at its worst period.
This often-occurring course of events might be illustrated from the history of the astronomical theory of epicycles and eccentrics, as is well known.
Thus the system of eccentrics and epicycles accounted for all the observed motions of the planets, and was the means of expressing and transmitting all astronomical knowledge for two thousand years.
These cycles and epicycles could not be true, because they could not be made a just representation of the facts.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "epicycles" in a variety of sentences. We hope that you will now be able to make sentences using this word.
