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

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1figure; and moveth circularly, hath neceſſarily, and in reſpect of
its figure a centre; and we being moreover certain, that within
the ſtarry Sphere there are many Orbs, the one within another,
with their ſtars, which likewiſe do move circulary, it is in diſpute
whether it is moſt reaſonable to believe and to ſay that theſe
teined Orbs do move round the ſaid centre of the World, or elſe
about ſome other centre far remote from that?
Tell me now
plicius what you think concerning this particular.
SIMP. If we could ſtay upon this onely ſuppoſition, and that

we were ſure that we might encounter nothing elſe that might
ſturb us, I would ſay that it were much more reaſonable to
firm that the Orb containing, and the parts contained, do all
move about one common centre, than about divers.
Its more
nal that the Orb
conteining, and the
parts conteined, do
move all about one
centre, than uoon
divers.
SALV. Now if it were true that the centre of the World is the

ſame about which the Orbs of mundane bodies, that is to ſay, of
the Planets, move, it is moſt certain that it is not the Earth, but
the Sun rather that is fixed in the centre of the World.
So that as
to this firſt ſimple and general apprehenſion, the middle place
belongeth to the Sun, and the Earth is as far remote from the
centre, as it is from that ſame Sun.
If the centre of
the World be the
ſame with that
bout which the
nees move the Sun
and not the Earth
is placed in it.
SIMP. But from whence do you argue that not the Earth, but
the Sun is in the centre of the Planetary revolutions?
SALV. I infer the ſame from moſt evident, and therefore
ceſſarily concludent obſervations, of which the moſt palpable to

exclude the Earth from the ſaid centre, and to place the Sun
therein, are, the ſeeing all the Planets one while neerer and
ther while farther off from the Earth with ſo great differences, that
for example, Venus when it is at the fartheſt, is ſix times more
remote from us, than when it is neereſt, and Mars riſeth almoſt
eight times as high at one time as at another.
See therefore
ther Ariſtotle was not ſomewhat miſtaken in thinking that it was
at all times couidiſtant from us.
Obſervations from
whence it is
lected that the Sun
and not the Earth
is in the centre of
the Celeſtial
lutions.
SIMP. What in the next place are the tokens that their
ons are about the Sun?
SALV. It is argued in the three ſuperiour planets Mars,
ter, and Saturn, in that we find them alwayes neereſt to the
Earth when they are in oppoſition to the Sun, and fartheſt off
when they are towards the conjunction, and this approximatian
and receſſion importeth thus much that Mars neer at hand,
peareth very neer 60 times greater than when it is remote.
As to

Venus in the next place, and to Mercury, we are certain that
they revolve about the Sun, in that they never move far from
him, and in that we ſee them one while above and another while

below it, as the mutations of figure in Venus neceſſarily argueth.
Tonchiug the Moon it is certain, that ſhe cannot in any way

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