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times as far before the earth as behind, her distance being not 

 very variable, and consequently her revolutions must necessarily 

 have the same measure of completeness as the earth's rotations. 

 Why, then, should we resist the conclusion to which all this leads, 

 namely, that the received opinion of astronomers on the subject 

 of the rotation of the planets and their satellites is erroneous ? 

 The only plausible answer I can anticipate is, that Galileo, and 

 Newton, and La Place, have sanctioned that opinion, and their 

 authority is better than mine. But is it better than right reason 

 and common sense together ? 



In the treatise on " Astronomy" published in " The Library 

 of Useful Knowledge,^'' I read, " We find not only that the du- 

 ration of a sidereal day is constant, but that during every part 

 of it the rotation goes on uniformly ; or, in other words, that the 

 heavens revolve round their axis continually with an uniform ve-- 

 locity. — The interval between the successive appearances of the 

 sun upon the meridian, or from noon to noon, is necessarily 

 longer than that between those of a star ; for as the motion of 

 the heavens is from east to west, and the proper motion of the 

 sun from west to east, the sun on each successive day, when the 

 point of the heavens where he was at noon on the day before returns 

 to the meridian is to the eastward of that point, and consequently 

 to the eastward of the meridian ; and he, therefore, only returns 

 to the meridian after the rotation of the heavens has continued 

 for some additional period, long enough to bring his new place 

 to the meridian, &c. The solar day is longer than the sidereal 

 day in consequence of the motion of the sun eastward in his or- 

 bit, &c." I have quoted these passages, not for the purpose of 

 making any direct comment upon the '' scientific truths" which 

 they embody ; for such a comment as they require has been al- 

 ready anticipated, or will be still introduced elsewhere. But 

 how could an author who seriously believes in the truth of the Co- 

 pernican system of the universe deliberately affirm, to use his 

 own italics, " that the heavens revolve round their axis continually 

 with an uniform velocity ;" or that '* the sun moves eastward in 

 an orbit ?" Such a way of speaking must inevitably puzzle and 

 perplex the readers of his book, as much as it seems to have 

 puzzled and perplexed himself; for his ideas on the subject of 

 the sun's and the earth's movements must have been utterly con- 

 founded when he affirmed to be positively true in fact, what 

 could only be true if the earth were really to be placed in the 

 centre of the orbit, and the sun were to be a planet revolving 

 round about her, namely, that the star outside, and not the sun 

 inside, is the true indicator of the earth's rotations, and of the 

 moon's revolutions. But, when the case is reversed ; when the 

 sun takes his proper place as the fixed centre of the orbit, and 



