When the Earth is at the beginning of Libra, namely on the 20th of _March_, in this Figure (as at _g_ in Fig. I.) the Sun _S_ as seen from the Earth appears at the beginning of Aries in the opposite part of the Heavens[53], the north Pole is just coming into the light, the Sun is vertical to the Equator; which, together with the Tropic of Cancer, parallel of _London_, and arctic Circle, are all equally cut by the Circle bounding light and darkness, coinciding with the six o’clock hour Circle, and therefore the days and nights are equally long at all places: for every part of the Meridian _ÆTLa_ comes into the light at six in the morning, and revolving with the Earth according to the order of the hour-letters, goes into the dark at six in the evening. There are 24 Meridians or hour-Circles drawn on the Earth in this Figure, to shew the time of Sun rising and setting at different Seasons of the Year. [Sidenote: Fig. II.] As the Earth moves in the Ecliptic according to the order of the letters _ABCD_, &c. through the Signs Libra, Scorpio, and Sagittarius, the north Pole comes more and more into the light; the days increase as the nights decrease in length, at all places north of the Equator _Æ_; which is plain by viewing the Earth at _b_ on the 5th of _May_, when it is in the 15th degree of Scorpio[54], and the Sun as seen from the Earth appears in the 15th degree of Taurus. For then, the Tropic of Cancer _T_ is in the light from a little after five in the morning till almost seven in the evening; the parallel of _London_ from half an hour past four till half an hour past seven; the polar Circle _U_ from three till nine; and a large track round the north Pole _P_ has day all the 24 hours, for many rotations of the Earth on it’s Axis. [Sidenote: Summer Solstice.] When the Earth comes to _c_, at the beginning of Capricorn, and the Sun as seen from the Earth appears at the beginning of Cancer, on the 21st of _June_, as in this Figure, it is in the position _a_ in Fig. I; and it’s north Pole inclines toward the Sun, so as to bring all the north frigid Zone into the light, and the northern parallels of Latitude more into the light than the dark from the Equator to the polar Circles; and the more so as they are farther from the Equator. The Tropic of Cancer is in the light from five in the morning till seven at night, the parallel of _London_ from a quarter before four till a quarter after eight; and the polar Circle just touches the dark, so that the Sun has only the lower half of his Disc hid from the inhabitants on that Circle for a few minutes about midnight, supposing no inequalities in the Horizon and no Refractions. [Sidenote: Autumnal Equinox. Winter Solstice.]