MOTION OF THE EARTH. The theory of gravitation has placed this question on a footing entirely different from that on which it was argued, whether by Ptolemaists or Copernicans. Both of the latter parties supposed the existence of a fixed central body somewhere, which the first of them would have to be the earth, and the second the sun. This centrum mundi, or centre of the universe, is exploded, and with it all the systems, whether Ptolemaic or Copernican, which preceded the discoveries of Newton. But, as noticed in COPERNICUS, in Bioo. Div., the existing system preserves the name of that great man ; the reason being, that its distinctive peculiarity is retaiued relatively, if not absolutely, namely, that the planets all move round the sun, or round a point near the sun. But it is added to the real Copernican system, that sun, planets, and all, may be, and probably are, in motion ; the translation, as it is called, of the whole system being very nearly rectilinear, and the curvature, if any, arising from the attraction of the fixed stars. Nothing but a long course of obser vation can settle this last part of the question, though much has been done of late years to establish the affirmative.
In approaching the old controversy on the motion of the earth, we confine ourselves rather to the arguments by which it was opposed than to those by which it was supported. For this we have two reasons : first, that the latter are well known and extensively circu lated, while the former, unless preserved in historical articles, will find the oblivion from which they have no intrinsic merit to rescue them; secondly, that the controversies of the present day may be usefully illustrated by recurring to the long-decided struggle between the Copernicans and their opponents. We have now among us those who would fetter all new truths by their interpretation of the Scriptures, though they quietly acquiesce in the defeat which their own principle formerly received. The charges still brought against the cultivators of the sciences, "to the distress and disgust of every well-constituted mind," as Sir J. Herschel expresses it, should be looked at, not as the honest manifestations of an alarm newly awakened by the circum stances of the present day, but as the effects of an abiding spirit, which has always opposed investigation, and which, if it had prevailed, would have smothered all the knowledge of nature which has been acquired in the last two centuries. If some of those who have con stituted themselves successors to the cardinals who forced Galileo to recant, have learnt from the past history of their own cause, and from the temper of the present age, to show the real scope of their system less openly than it appeared in the 17th century, the compliment which they thus pay to the advancing intelligence of mankind, though received with thanks and highly appreciated, should not be accepted as an equivalent for the mischiefs which must result from a successful attempt to place the great question of Revelation upon a false basis. The case of those who now endeavour to impede the progress of geology, or to limit speculation on the process of creation, is so similar in its fundamental points with that of the labourers to the same effect in the field of astronomy, that the circulation of some account of the latter will perhaps enable our readers to help themselves in forming their opinion of the former.
When the work of Copernicus appeared in 1543, it seems to have been considered as a mere attempt to demonstrate (see the old use of this word in DEMONSTRATION) the motions of the heavenly bodies in a more simple way. Guarded as it was by the expressions of the preface, it was neglected as a purely speculative trial of a strange and impossible hypothesis. In 1566 Ramus (` Scol. Math.') simply reproaches Coper nicus with the gigantic character of his hypothesis, and says it would have been better to have taken one nearer to the truth, in a manner which implies that he thought both were agreed as to what the truth really was. Copernicus himself, as we have seen, treated his own ideas as a reproduction of those of the ancients, and in truth the existence of such a doctrine as the earth's motion was perfectly well known to all men of learning. Aristotle (in his second book on the Heavens) states that Pythagoras and his followers placed the sun in the centre, on account of the superior excellence which they attributed to the element of fire, of which they supposed the sun to be made. Different authorities give the same opinion (whether with or without the reason) to Philolaus, Anaximandcr, Nicetas, Seleucus, Cleanthes, Leucippus, Ecphantus, Heraclides Ponticus, and Aristarchus. The introduction of Pythagoras, as a predecessor of Copernicus, is as rational as would be the connection of the modern atomic theory with the doctrines of Epicurus; and much of the same kind is an assertion not unfrequently made, that Cardinal Cusa was a supporter of the earth's motion. This writer (` De Doctft Ignorantift,' lib. ii., c. 11) certainly denies that there can be any centre of the universe ; for, says he, if there were a centre, there would be a circumference, that is, a termination, to the universe; and his reasons relative to the earth's motion are of the same degree of force. He is more rational in the next chapter, where ho explains that the apparent motion of other bOti ie• may be that of the spectator. Iticcioll cites a sermon of Casa, which proves, say. he, that the cardinal had come to a sounder' opinion; for he speaks of God's angels or intelligences moving tho sun and stars. Nothing can better illustrate, in our opinion, the arguments against Riocioli and his predecessors : when tho cardinal is writing for men of science, ho advances, after his fashion, speculation about the earth's motion ; when he is writing excitations not exereitationc, as Riccioli says) to religious feeling, he speaks of God's works in a manner which persons in general understood; in confounding the preacher of religion with the philosopher, Iticcioli made the usual error of his day, and only repeated his own mode of treating Moses, Isaiah, and the writer of Job. lint it would have been better to have argued by analogy, that if either of the latter had written a professedly philoso phical work, he might, whatever appears to the contrary from his religious writings, have admitted the motion of the earth.