176

Herevpon it was desired that a tryall might be made of it wth a pole of 10
foot long that thereby the Society might be satisfyd of the . . .
practicablenesse thereof : wch mr. Hooke vndertooke to doe -

Seuerall Discourses were made likewise about the nature of A penumbra
of wch. the Result was that it was concluded to arise from the Partile inlight
tning of the Parts in the penumbra. some parts of the luminous body
being hidd from them whilst they were shined vpon by other

then mr Hooke read a Discourse of mor Cassini concerning his further prose
cuting of the Discouery of the Diurnall motion of vpon its axis.
by the spott obseruable in one of its belts. wherein were seuerall very
remarkable circumstances and Discouerys as first that the said spott
did sometimes appear for a certaine space and then disappear againe
for a certaine space. that the belts also changed and the two belts
did as if /they/ were into two riuer that ouerflowd their banks and Run into
one large one wth only some small spotts or Islands as it were between
them. that this turbinated motion of was sometimes swifter &
sometimes slower according as it did more or lesse approach the Sun.
that he had stated the Epoche thereof and had giuen the Rule how
to calculate for the future. that thereby the times of it comming to the
middle of the Disk might be obserued to some few minutes of time
that from the greate number of reuolutions mr Cassinj haue Diuided by
the whole space from the first to the last by the said number found
it to be sometimes 9h. 55'. 531/2''. sometimes 9h. 55', 52''. .6''' -

Dr. Croon produced a Phosphorus the same wth that of Baldwinus
wch. he affirmd was made here in England by an Englishman
altogether as good as that sent by mr Baldwine himself

mr. Haak affirmed that he had another of the same kind and that
had obserued that it . . . appeard white if it were exposed to the
light in the euening when the sun was almost ready to set.

Ref: CELL/RS/HF_178  © Centre for Editing Lives and Letters