having more or less _Aperture_, or from the
difficulty of making an exact estimate of their proportions. However it is
not much wide (saith he) of two and a half, although _Campani_ make the
length of the _Ring_ but double to its breadth.

Monsieur _Auzout_ believes, that he was one of the first that have well
observed this shadow of _Saturn's_ Body upon its _Rings_ which he affirms
happened two years since; when, observing in _July_, for the first time,
with a _Telescope_ of 21. and then another of 27. foot, he perceived, that
the _Angle_ of the obscure space on the _right side_ beneath, was bigger
and wider, than the three other _Angles_, and that some interruption
appear'd _there_, between the _Ring_, and the _Body of Saturn_; of which he
saith to have given notice from that time to all his friends, and in
particular, as soon as conveniently he could, to Monsieur _Hugens_.

He confesseth, that he hath not had the opportunity of observing _Saturn_
in his _Oriental Quadrat_; yet he doubts not, but that the _shadow_ appears
on the _Left-side_, considering, that the _Existence_ of the _Ring_ can be
no longer doubted of, after so many _Observations_ of the _shadow_ cast by
_Saturn's_ Body upon it, according as it must happen, following that
_Hypothesis_; there being no reason, why it should cast the said _shadow_
on one side, and not on the other.

Concerning the Observation of _Jupiter_ and its _satellites_, the famous
_Astronomer_ of _Bononia_, _Cassinus_, having {73} published, that on the
30. day of _July_, 1664. at 21/2 of the clock in the morning, he had
observ'd, with _Campani_'s Glasses, that there passed through the broad
obscure _Belt_ of _Jupiter_ two obscurer _spots_, by him esteemed to be the
_shadows_ of the _Satellites_, moving between _Jupiter_ & the _Sun_, and
eclipsing him, and emerging from the Occidental Brim thereof: This
_Authour_ did first conceive, that they were not _shadows_, but some
_Sallies_, or _Prominencies_ in that _Belt_; which he was induced to
believe, because he perceived not, that that _Prominency_, which he there
saw, was so black, nor so round as _Cassini_ had represented his _spots_;
wherefore, seeing it but little differing in colour, from the _Belt_, and
so not judging it round, because it did stand only about half its diameter
out of the _Belt_, he persuaded himself, that it was rather a _Sally_, or
_Prominency_ of the _Belt_, than a round _shadow_, as that of a _Satellite_
of