339. Thus it appears, that from the vernal equinox to the autumnal, the North Pole is enlightened; and the Equator and all its parallels appear Semi-ellipses as seen from the Sun, more or less curved as the time is nearer to or farther from the Summer Solstice; and bending downwards or towards the South Pole; the reverse of which happens from the autumnal Equinox to the vernal. A little consideration will be sufficient to convince the reader, that the Earth’s Axis inclines towards the Sun at the Summer Solstice; from the Sun at the Winter Solstice; and sidewise to the Sun at the Equinoxes; but towards the right hand, as seen from the Sun at the vernal Equinox; and towards the left hand at the autumnal. From the Winter to the Summer Solstice, the Earth’s Axis inclines more or less to the right hand, as seen from the Sun; and the contrary from the Summer to the Winter Solstice. [Sidenote: How these positions affect solar Eclipses.] 340. The different positions of the Earth’s Axis, as seen from the Sun at different times of the year, affect solar Eclipses greatly with regard to particular places; yea so far as would make central Eclipses which fall at one time of the year invisible if they fell at another, even though the Moon should always change in the Nodes and at the same hour of the day: of which indefinitely various affections, we shall only give Examples for the times of the Equinoxes and Solstices. [Sidenote: Fig. IV.] In the same Diagram, let _FG_ be part of the Ecliptic, and _IK_ _ik_ _ik_ _ik_ part of the Moon’s Orbit; both seen edgewise, and therefore projected into right lines; and let the intersections _N_, _O_, _D_, _E_ be one and the same Node at the above times, when the Earth has the forementioned different positions; and let the spaces included by the Circles _P_, _p_, _p_, _p_ be the Penumbra at these times, as its center is passing over the center of the Earth’s Disc. At the Winter Solstice, when the Earth’s Axis has the position _NNS_, the center of the Penumbra _P_ touches the Tropic of Capricorn _t_ in _N_ at the middle of the general Eclipse; but no part of the Penumbra touches the Tropic of Cancer _T_. At the Summer Solstice, when the Earth’s Axis has the position _NDS_ (_iDk_ being then part of the Moon’s Orbit whose Node is at _D_) the Penumbra _p_ has its center on the Tropic of Cancer _T_ at the middle of the general Eclipse, and then no part of it touches the Tropic of Capricorn _t_. At the autumnal Equinox the Earth’s Axis has the position _NOS_ (_iOk_ being then part of the Moon’s Orbit) and the Penumbra equally includes part of both Tropics _T_ and _t_ at the middle of the general Eclipse: at the vernal Equinox it does the same, because the Earth’s Axis has the position _NES_: But, in the former of these two last cases, the Penumbra enters the Earth at _A_, north of the Tropic of Cancer _T_, and leaves it at _m_, south of the Tropic of Capricorn _t_;