SECTION XVIII. 267 everynation, and whatsoever has rendered pit worthy of public notice in the world. There are many books extant in the world on this subject; some of lesser size, such as Gordon's Geographical Grammar, Chamberlain's Geography; and larger, viz. Moden's Geogra- phy Rectified, in quarto, Thesaurus Geographicus, Moll's Geo- graphy, in folio, &c. The second or special part of astronomy is called the theory of the heavens, or the sun and planets, which will lead us into the knowledge of a thousand beautiful and entertaining truths con- cerning the system of the world, the various appearances of the heavenly bodies, and the reasons of those appearances, viz. a more particular and exact account of the day and night, and of the several seasons of the year, spring, summer, autumn, and winter, of the length and shortness of the days. Why in the winter the sun is nearer to us than it is in the summer, and why the winter half-year is seven or eight daysshorter than the summer half-year. Whence come the eclipses of the sun and moon, both total and partial ; why the moon is only eclipsed when she is full, and the Sun only when she is new : Whence proceed the different phases of the moon, as the new or horned moon, the half-moon, the full, &c. Why the two lower planets Mercury and Venus always keep near the sun, and never move so far as two whole signs from it : Why Venus is horned, halved and full as the moon is. Why the three superior planets Mars, Jupiter and Saturn, appear at all distances from the sun, and are sometimes quite opposite to it. Why both the upper and lower planets sometimes appear swifter, sometimes slower ; why they seem sometimes to move directly or forward, sometimes retrogade or backward, sometimes are stationary, or seem to stand still. Why they are sometimes nearer to the earth, which is called their perigeum, and sometimes farther from the earth, which is called their apogeum, and by this means ap- pear greater or less. Why they are nigher to or farther from the sun, which is called their perihelion and aphelion ; and in what part of their orbits this difference falls out. How it comes to pass that they seem higher in the horizon than really they are by refraction, andhow againthey seem lower than they really are iay theparallax. In this part of astronomy it is proper to shew the different schemes or hypotheses that have been invented to solve or explain all these appearances of the-heavenly bodies. Here the Ptolematic or ancient system should have the first place, to represent how the ancients placed the earth in the centre of the world, and supposed the sun to move round it amongst the other planets as it appears to the vulgar eye ; and what tedious and bungling work they madeby their contrivance of solid transparent spheres
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