130. Because the Stars never vary their distances from the Equinoctial, so as to be sensible in an age, the lengths of their diurnal and nocturnal Arcs are always the same to the same places on the Earth. But as the Earth goes round the Sun every year in the Ecliptic, one half of which is on the north side of the Equinoctial and the other half on it’s south side, the Sun appears to change his place every day, so as to go once round the Circle _YCX_ every year § 114. Therefore whilst the Sun appears to advance northward, from having described the Parallel _abX_ touching the Ecliptic in _X_ the days continually lengthen and the nights shorten, until he comes to _y_ and describes the Parallel _yzx_, when the days are at the longest and the nights at the shortest: for then, as the Sun goes no farther northward, the greatest portion that is possible of the diurnal Arc _yz_ is above the Horizon of the inhabitant _i_; and the smallest portion _zx_ below it. As the Sun declines southward from _y_ he describes smaller diurnal and greater nocturnal Arcs, or Portions of Circles, every day; which causeth the days to shorten and nights to lengthen, until he arrives again at the Parallel _abX_; which having only the small part _ab_ above the Horizon _MCL_, and the great part _bX_ below it, the days are at the shortest and the nights at the longest; because the Sun recedes no farther south, but returns northward as before. It is easy to see that the Sun must be in the Equinoctial _ECQ_ twice every year, and then the days and nights are equally long; that is, 12 hours each. These hints serve at present to give an idea of some of the Appearances resulting from the motions of the Earth; which will be more particularly described in the tenth Chapter. [Sidenote: Fig. I. Parallel, Oblique, and Right sphere, what.] 131. To an observer at either Pole, the Horizon and Equinoctial are coincident; and the Sun and Stars seem to move parallel to the Horizon: therefore, such an observer is said to have a Parallel position of the Sphere. To an observer any where between the Poles and Equator, the Parallels described by the Sun and Stars are cut obliquely by the Horizon, and therefore he is said to have an Oblique position of the Sphere. To an observer any where on the Equator, the Parallels of Motion, described by the Sun and Stars are cut perpendicularly, or at Right angles, by the Horizon; and therefore he is said to have a Right position of the Sphere. And these three are all the different ways that the Sphere can be posited to all people, on the Earth. CHAP. V. _The Phenomena of the Heavens as seen from different Parts of the Solar System._