171

march. 7. 1677/8

mr. Henshaw the vice president tooke the chair

mr Hooke read the minutes of the Last Day, vpon the mention of the air Poise
and the experiment in order to proue it of weighing two bodys in water
and It was very much doubted whether though ^ /by/ the experiment of weighing
in water the instrument did become sensible soe as to turne by putting
a little salt yet into the water yet whether the very small changes of Grauity could
of the air could be made sensible by such an Insrument but mr Hooke affirmed
that he could and that in order therevnto he would prouide a glasse blown
large and light on purpose and soe order it as that its variation or difference
should be 10 or twenty foot if it were necessary and consequently capable
of Discouering the smallest alterations thereof.

He further added that he would shortly bring bring in a new instrument
for . . . the Discouery of some proprietys of the Atmosphere not yet known
or taken notice of and as yet altogether insensible to vs though by
the said Instrument they would be made euident and their natures
Discouerd & Determined.

vpon the mentioning of the Particulars taken notice of by mr Gallet of
the ouall figure of mercury the matter was further Discoursd and mr.
Hooks hypothesis was obiected against . vizt. that though such an ouall
figure would be causd by the whirling round of a fluid body yet twas -
probable that the body of was solid and consequently It could haue
noe effect vpon it. to which mr. Hooke answered that though it might
possibly be now a solid body yet that that at the beginning it might haue
been fluid enough to Receiue that shape, And that though that suppo
sition would not be granted yet it was probable that there might be about
mercury some fluid body somewt. of the nature of the Sea herevpon
the earth, wch if that could be granted It would be probable enough that
that would readily run into that shape and make the same appearance, and
that twas not improbable but that the water here about the earth might
doe it in Some measure . . . by the influence of the Diurnall moti
on wch. compounded wth. that of the moon he conceiud was the cause of
the tydes. But there were some other ways of explicating these appearances
which when he had time he Designed to Draw vp in writing

Some obiections hauing been made against the way of making vse of long telescopes
wthout tubes mr. Hooke further explaind the way and answerd all those obiections
and particularly that of Sr. Ionas more who supposed it only theory and that
It had not been practised or made vse of . . . by affirming that he had ac
=tually done it and found it conuenient enough in a glasse of 28 foot and ther
fore he conceiud it might be as conueniently practised in a glasse of any other
Length. - .

Ref: CELL/RS/HF_173  © Centre for Editing Lives and Letters