ugh, if the declination of the _Ring_ remains always the same, one can
at all times know, which may have been its greatest breadth. But he
assures, that the breadth of the _Ring_ is not the half of its length, and
that it doth not spread out so much beyond _Saturn_'s Body, as he hath
alleged. And withal desirs to know, what can be answered by Sig. _Campani_
to M. _Hugens_, who being persuaded, that the Declination of the _Ring_ is
not above 23 deg. 30' having seen the _Ring_ to spread out above the Body
of _Saturn_, concludes, in a Letter to M. _Auzout_, that the length of the
_Ring_ is more than treble the _Diameter_ of _Saturn_'s body, which,
according to _Campani_, is only as about 67 to 31. Which difference yet dos
not appear to M. _Auzout_ to be so great; but that M. _Hugens_ perhaps will
impute it to the Optical reason, which he (_Auzout_) hath alleged of the
Advance of the light upon the obscure space; although he is of Opinion, he
should not have concluded so great a Length, if he had not seen the Breadth
spread out more, than he hath done: for (_saith he_) if the Length of the
_Ring_ be to the body of _Saturn_, 21/2 to 1. and the _Inclination_ be 23
deg. 30' the _Ring_ will be just as large, as the body, without spreading
out; but if the _Ring_ be bigger, it will a little spread out; and if it
were treble, it must needs spread out the half of its breadth, which hath
not so appeared to him.

Further, to M. _Auzout's_ change of Opinion, and believing, that the
_Advance_ or _Sally_, seen by him in _Jupiter_, was the _Shadow_ of one of
his Moons, _Campani_ declares, that he would not have him guilty of that
change: Whereupon M. _Auzout_ wonders, why _Campani_ then hath not marked
it in his _Figure_; and would {77} gladly know, whether that _Sally_ be
more easie to discover, than the _Shadows_ of the _Satellites_, which
_Campani_ believs, _Auzout_ hath not seen; and whether he be assured, that
those obscure parts, which he there distinguishes, do not change: for if
they should not change, then _Jupiter_ would not turn about his _Axis_,
which yet, he saith, it doth, according to the _Observation_ made by Mr.
_Hook_, _May_ 9 1664. inserted in the first papers of these _Transactions_.
The full Discovery of which particular also he makes to be a part of
_Cassini's_ and _Campani_'s work, seeing that they so distinctly see the
inequalities in the _Belts_, and see also sometimes other _Spots_ besides
the _Shadows_ of the _Sa