Let _a_, _b_, _c_, _d_, _e_, _f_, _g_, _h_ be the Earth in eight different parts of it’s Orbit, equidistant from one another; _Ns_ it’s Axis, _N_ the north Pole, _s_ the south Pole, and _S_ the Sun nearly in the center of the Earth’s Orbit § 18. As the Earth goes round the Sun according to the order of the letters _abcd_, &c. it’s Axis _Ns_ keeps the same obliquity, and is still parallel to the line _MNs_. When the Earth is at _a_, it’s north Pole inclines toward the Sun, and brings all the northern places more into the light than at any other time of the year. But when the Earth is at _e_ in the opposite time of the year, the north Pole declines from the Sun, which occasions the northern places to be more in the dark than in the light; and the reverse at the southern places, as is evident by the Figure, which I have taken from Dr. LONG’s Astronomy. When the Earth is either at _c_ or _g_, it’s Axis inclines not either to or from the Sun, but lies sidewise to him; and then the Poles are in the boundary of light and darkness; and the Sun, being directly over the Equator, makes equal day and night at all places. When the Earth is at _b_ it is half way between the Summer Solstice and Harvest Equinox; when it is at _d_ it is half way from the Harvest Equinox to the Winter Solstice; at _f_ half way from the Winter Solstice to the Spring Equinox: and at _h_ half way from the Spring Equinox to the Summer Solstice. [Sidenote: Fig. II. PLATE V. The Ecliptic. The seasons shewn in another view of the Earth, and it’s Orbit.] 203. From this oblique view of the Earth’s Orbit, let us suppose ourselves to be raised far above it, and placed just over it’s center _S_, looking down upon it from it’s north pole; and as the Earth’s Orbit differs but very little from a Circle, we shall have it’s figure in such a view represented by the Circle _ABCDEFGH_. Let us suppose this Circle to be divided into 12 equal parts called _Signs_, having their names affixed to them; and each Sign into 30 equal parts called _Degrees_, numbered 10, 20, 30, as in the outermost Circle of the Figure, which represents the great Ecliptic in the Heavens. The Earth is shewn in eight different positions in this Circle, and in each position _Æ_ is the Equator, _T_ the Tropic of Cancer, the _dotted Circle_ the parallel of _London_, _U_ the arctic or north polar Circle, and _P_ the north Pole where all the Meridians or hour Circles meet § 198. As the Earth goes round the Sun the north Pole keeps constantly towards one part of the Heavens, as it keeps in the Figure towards the right hand side of the Plate. [Sidenote: Vernal Equinox.]