Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/445

 to all the Stars, as is this diurnal one: yet I believe that in few dayes they perceived that the Moon was inconstant in keeping company with the other Stars; but yet withal, that many years past, before that they distinguished all the Planets: And in particular, I conceit that Saturn by its slowness, and Mercury by reason of its seldom appearing, were the last that were observed to be wandring and errant. It is to be thought that many more years run out before the stations and retrogradations of the three superiour Planets were known, as also their approximations and recessions from the Earth, necessary occasions of introducing the Eccentrix and Epicicles, things unknown even to Aristotle, for that he makes no mention thereof. Mercury, and Venus, with their admirable apparitions; how long did they keep Astronomers in suspence, before that they could resolve (not to speak of any other of their qualities) upon their situation? Insomuch that the very order onely of the Mundane bodies, and the integral structure of the parts of the Universe by us known, hath been doubted of untill the time of Copernicus, who hath at last given us notice of the true constitution, and real systeme, according to which those parts are disposed; so that at length we are certain that Mercury, Venus, and the other Planets do revolve about the Sun; and that the Moon revolveth about the Earth. But how each Planet governeth it self in its particular revolution, and how precisely the structure of its Orb is framed; which is that which is vulgarly called the Theory of the Planets, we cannot as yet undoubtedly resolve. Mars, that hath so much puzled our Modern Astronomers, is a proof of this: And to the Moon her self there have been assigned several Theories, after that the said Copernicus had much altered it from that of Ptolomy. And to descend to our particular case, that is to say, to the apparent motion of the Sun and Moon; touching the former, there hath been observed a certain great irregularity, whereby it passeth the two semicircles of the Ecliptick, divided by the points of the Equinoxes in very different times; in passing one of which, it spendeth about nine dayes more than in passing the other; a difference, as you see, very great and notable. But if in passing small arches, such for example as are the twelve Signs, he maintain a most regular motion, or else proceed with paces, one while a little more swift, and another more slow, as it is necessary that it do, in case the annual motion belong to the Sun onely in appearance, but in reality to the Earth in company with the Moon, it is what hath not hitherto been observed, nor it may be, sought. Touching the Moon in the next place, whose restitutions have been principally lookt into an account of the Eclipses, for which it is sufficient to have an exact knowledge of its motion about the Earth,