129

(3)

mr. George Ent Presentd the Society for their library the Catalogue of
the Bodleyan Library. for wch. he Reciued the Thanks of the Society and
the booke was deliuerd to mr. Hunt to put into the Library,

After this Mr Hooke shewd a hydrostaticall experiment mentioned the Last Day
. . . wch. was in order to explaine how the mutations of the Baroscope were
occasioned by the Differing pressure of the air, which pressure was sometimes
greater sometimes lesse according as the exhalations or vapours raised vp into the
same doe augment the specifique grauity of . . . it and the bulk
also or perpendicular altitude of thereof. This he made appear by the
meanes of very high body of glasse filled wth. water into the which was
Let down ^ /a standerd of pressure made by/ a tube bended tube of glasse in wch. mercury was put wch. as it Descend
ed Deeper into the water and consequently the Pressure increasd was raised in
one Leg and Depressed in the other Leg thereof. then A bladder was tyed to the
end of the an other glasse cane and by the breath after it was sunk down
into the water was blown vp by wch. the Bulk of the fluid was Incl increased
though not the specifique grauity and thereby the perpendicular alti
tude of the pressing fluid was increased and consequently the Pressure
vpon the mercury in the standard. the same was veryfyed by a farther
tryall made wth. Large bottell of quick siluer close stopped and
lett down into the body of the said water. and it was alledged that by
Mr Hooke that the same appear effects would follow from wteuer body
it were that were thus putt into the fluid and augmented the bulk
thereof. wthout at all altering the specifique grauity of the same

Dr croon alledged that the same liquor by being put in differing ^ /cylinders & soe differng/ postures
did much ag augment the pressure of the same quantity of fluid vpon
the Respective bottoms.

But mr. Hook alledged that the same quantity of a fluid body though
putt in neuer soe ^ /much/ differing cylinders the /whole/ pressure of the said fluid
vpon the whole bottom of the one would be aequall to the whole pressu[re]
of the other vpon the whole bottom of the second. because the grauity
of the fluid must be the same in all postures. and the space possessed
by the same would also be aequall for as the base of the bigger to
the base of the Lesse soe the perpendicular altitude of the Lesse so
the perpendicular altitude of the bigger.

But to this the Doctor could not assent but alledged he could make out
the contrary by Expt. -

Ref: CELL/RS/HF_131  © Centre for Editing Lives and Letters