th while, to be hereafter more diligent and curious in this particular,
and accurately to observe in the _Phasis_ of each _Digit_ the _Proportion_
of the _Semidiameters_ of both Luminaries; to the end, that _first_ it may
be made manifest, Whether in all the _Eclipses_ of the _Sun_, or in some
only, that variation happens; _next_, that the Causes of such a
_Phaenomenon_ may be diligently inquired into. Of this Variation, the
Excellent _Ismael Bullialdus_ hath also observed something at _Paris_. For
he has written to me, That in the same Eclipse the _Semidiam._ of the _Sun_
to the _Semid._ of the _Moon_ was, as 16'. 9". to 16'. 22"; but that in
another {348} _Phasis_ of 6 _digits_, the Semidiameters appear'd equal.
These my Observations, if you think them worthy, you may communicate to
other Mathematicians. The last year 1665. _July_ 27. (_st. n._) the
_Tables_ did also indicate an Eclipse of the _Moon_: but though the Sky
here was very cleer, yet the Moon was not at all obscured by the _true
shadow_, but entred only a little into the _Penumbra_, wherein it continued
50'. The beginning of its touching the _Penumbra_ did then almost happen,
when _Aquila_ was elevated 36 deg. 18'; which is an Example worthy to be noted.
I have many Observations of the _Eclipses_ of former years by me, which I
could not yet make publick, by reason of the multitude of my business,
which do almost over-whelm me. The Eclipse of the Moon of this Year 1666.
_June_ 16. (_st. n._) was observed from a Hill neer my Garden, to the end,
that we might see both together the _Suns setting_, and the _Moon rising_.
But I was disappointed of my hopes: For very thick Exhalations, besieging
the _Horizon_, where the Moon was to rise, unto 2 deg.. 30', hindred me from
seeing the _Moon rise_, in the Article of the _setting_ of the _Sun_.
Wherefore the first _Phasis_ of 1. _dig_. 45'. did not appear but in the
_Moons Altitude_ of 2 deg.. 30'; when the greatest Obscuration was already
past. The _End_ fell out hor. 9. 27'. about 128 deg. from the _Zenith_
Westward.

[Sidenote: * A Letter, written since from _Paris_, advertises, that some of
the Curious there have received one of these Glasses of _Sr. Burattini_,
and do esteem it to be good without mentioning the Dimension of it: which
yet is look'd for by the next.]

I am very glad to understand, that you have so good _Telescopes_, as to
make such considerable Observations in _Jupiter_ and _Mars_, as you have
latel