Salusbury, Thomas, Mathematical collections and translations (Tome I), 1667

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1circle that is the Terminator of the light; therefore this ſame
circle ſhall paſſe by the Poles A B in the fourth figure, and
in its plain the Axis A B ſhall fall, but the greateſt circle paſſing
by the Poles of the Parallels, divideth them all in equal parts;
therefore the arches I K, E F, C D, G N, L M, ſhall be all
ſemicircles, and the illumin'd Hemiſphere ſhall be this which
looketh towards us, and the Sun, and the Terminator of the
light ſhall be one and the ſame circle A C B D, and the Earth
being in this place ſhall make it Equinoctial to all its Inhabitants.
And the ſame happeneth in the ſecond figure, where the Earth
having its illuminated Hemiſphere towards the Sun, ſheweth us
the other that is obſcure, with its nocturnal arches, which in
like manner are all ſemicircles, and conſequently, here alſo it
maketh the Equinoctial.
And laſtly in regard that the line
duced from the centre of the Sun to the centre of the Earth, is
perpendicular to the Axis A B, to which the greateſt circle of
the parallels C D, is likewiſe erect, the ſaid line O Libra ſhall
paſſe of neceſſity by the ſame Plain of the parallel C D, cutting
its circumference in the midſt of the diurnal arch C D; and
therefore the Snn ſhall be vertical to any one that ſhall ſtand
where that interſection is made; but all the Inhabitants of that
Parallel ſhall paſſe the ſame, as being carried about by the
Earths diurnal converſion; therefore all theſ upon that day
ſhall have the Meridian Sun in their vertex.
And the Sun at the
ſame time to all the Inhabitants of the Earth ſhall ſeem to
ſcribe the Grand Parallel called the Equinoctial.
Furthermore,
foraſmuch as the Earth being in both the Solſtitial points of the
Polar circles I K and L M, the one is wholly in the light, and
the other wholly in the dark; but when the Earth is in the
noctial points, the halves of thoſe ſame polar circles are in the
light, the remainder of them being in the dark; it ſhould not
be hard to underſtand, how that the Earth v. gr. from Cancer
(where the parallel I K is wholly in the dark) to Leo, one part of
the parallel towards the point I, beginneth to enter into the light,
and that the Terminator of the light I M beginneth to retreat
wards the Pole AB, interſecting the circle ACBD nolonger in IM,
but in two other points falling between the terms I A and MB, of
the arches IA and M B; whereupon the Inhabitants of the circle
begin to enjoy the light, and the other Inhabitants of the circle
L M to partake of night.
And thus you ſee that by two ſimple
motions made in times proportionate to their bigneſſes, and not
contrary to one another, but performed, as all others that
long to moveable mundane bodies, from Weſt to Eaſt aſſigned
to the Terreſtrial Globe, adequate reaſons are rendred of all
thoſe Phænomena or appearances, for the accommodating of

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