1be perpendicular to the ſame D E, by reaſon that the Colure is
erect upon the grand Orb; and therefore the ſaid D E,
ſhall be the Tangent of the grand Orb in the point A.
So that in this Poſition the motion of the Centre by the arch
A E; that is, of one degree every day differeth very little; yea,
is as if it were made by the Tangent D A E. And becauſe by
means of the diurnal motion the point D, carried about by G,
unto E, encreaſeth the motion of the Centre moved almoſt in the
ſame line D E, as much as the whole diameter D E amounts
unto; and on the other ſide diminiſheth as much, moving about
the other ſemicircle E F D. The additions and ſubductions
in this place therefore, that is in the time of the ſolſtice, ſhall be
meaſured by the whole diameter D E.
erect upon the grand Orb; and therefore the ſaid D E,
ſhall be the Tangent of the grand Orb in the point A.
So that in this Poſition the motion of the Centre by the arch
A E; that is, of one degree every day differeth very little; yea,
is as if it were made by the Tangent D A E. And becauſe by
means of the diurnal motion the point D, carried about by G,
unto E, encreaſeth the motion of the Centre moved almoſt in the
ſame line D E, as much as the whole diameter D E amounts
unto; and on the other ſide diminiſheth as much, moving about
the other ſemicircle E F D. The additions and ſubductions
in this place therefore, that is in the time of the ſolſtice, ſhall be
meaſured by the whole diameter D E.
Let us in the next place enquire, Whether they be of the ſame
bigneſs in the times of the Equinoxes; and tranſporting the
Centre of the Earth to the point I, diſtant a Quadrant of a
Circle from the point A. Let us ſuppoſe the ſaid Equinoctial
to be G E F D, its common ſection with the grand Orb D E, the
Axis with the ſame inclination C B; but the Tangent of the grand
Orb in the point I ſhall be no longer D E, but another which
ſhall cut that at right Angles; and let it be this marked H I L,
according to which the motion of the Centre I, ſhall make its
greſs, proceeding along the circumference of this grand Orb.
Now in this ſtate the Additions and Subſtractions are no longer
meaſured by the diameter D E, as before was done; becauſe that
diameter not diſtending it ſelf according to the line of the annual
motion H L, rather cutting it at right angles, thoſe terms D E, do
neither add nor ſubſtract any thing; but the Additions and
Subſtractons are to be taken from that diameter that falleth
in the plane that is errect upon the plane of the grand Orb, and
that interſects it according to the line H L; which diameter in this
caſe ſhall be this G F and the Adjective, if I may ſo ſay, ſhall
be that made by the point G, about the ſemicircle G E F, and the
Ablative ſhall be the reſt made by the other ſemicircle F D G.
Now this diameter, as not being in the ſame line H L of the
annual motion, but rather cutting it, as we ſee in the point I, the
term G being elevated above, and E depreſſed below the plane
of the grand Orb, doth not determine the Additions and
ſtractions according to its whole length, but the quantity of thoſe
firſt ought to be taken from the part of the line H L, that is
tercepted between the perpendiculars drawn upon it from the
terms G F; namely, theſe two G S, and F V: So that the
ſure of the additions is the line S V leſſer then G F, or then D E;
which was the meaſure of the additions in the Solſtice A. And
ſo ſucceſſively, according as the centre of the Earth ſhall be
bigneſs in the times of the Equinoxes; and tranſporting the
Centre of the Earth to the point I, diſtant a Quadrant of a
Circle from the point A. Let us ſuppoſe the ſaid Equinoctial
to be G E F D, its common ſection with the grand Orb D E, the
Axis with the ſame inclination C B; but the Tangent of the grand
Orb in the point I ſhall be no longer D E, but another which
ſhall cut that at right Angles; and let it be this marked H I L,
according to which the motion of the Centre I, ſhall make its
greſs, proceeding along the circumference of this grand Orb.
Now in this ſtate the Additions and Subſtractions are no longer
meaſured by the diameter D E, as before was done; becauſe that
diameter not diſtending it ſelf according to the line of the annual
motion H L, rather cutting it at right angles, thoſe terms D E, do
neither add nor ſubſtract any thing; but the Additions and
Subſtractons are to be taken from that diameter that falleth
in the plane that is errect upon the plane of the grand Orb, and
that interſects it according to the line H L; which diameter in this
caſe ſhall be this G F and the Adjective, if I may ſo ſay, ſhall
be that made by the point G, about the ſemicircle G E F, and the
Ablative ſhall be the reſt made by the other ſemicircle F D G.
Now this diameter, as not being in the ſame line H L of the
annual motion, but rather cutting it, as we ſee in the point I, the
term G being elevated above, and E depreſſed below the plane
of the grand Orb, doth not determine the Additions and
ſtractions according to its whole length, but the quantity of thoſe
firſt ought to be taken from the part of the line H L, that is
tercepted between the perpendiculars drawn upon it from the
terms G F; namely, theſe two G S, and F V: So that the
ſure of the additions is the line S V leſſer then G F, or then D E;
which was the meaſure of the additions in the Solſtice A. And
ſo ſucceſſively, according as the centre of the Earth ſhall be