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He also mentioned that he had an hypothesis by wch. the Phenomena of the Ba
roscope would be more cleerly and Distinctly made out then by any
he had hitherto seen heard of, to wit of Diuiding and Distinguishing the
two principles or causes wch. actuate the said instrument from wch..
Distinction It will be easy toshew the reason why at Differing times
the same altitude of the foreshews Different constitutions of the weather
Dr. Wallis affirmd it would vary wth. keeping MrHook affirmd not

He also vpon this occasion acquainted the President & Society that he had a
baroscope making which would make the alteration of the pressure of the
air as euident as it should be Desired and that Instead of two inches
or thereabouts which was the Difference that ^/is/ usually obserud between
the highest and Lowest altitude of the vper surface of the aboue
the Lower he could by this make that Difference two foot or _
two yards or two fathoms or more if it should for any vse
be found necessary.
Dr. Croon mentioned Related that Sr. Peter Colleton had taken care to
send seuerall baroscopes to the Barbadoes in order to examine whe
ther they would be of any vse for the foretelling the seasons and
mutations of the weather as they were found to doe here -
Especially concerning hurricanes
mr.. Oliuer Hill made some querys concerning the vse of & S.V.
in the making of the Baroscope. and it was answerd that was
made vse of by reason of its great weight & soe Diminishing that
Instrument from 35 foot to 30 inches. and Spt. of Wine by reason
both of its easinessand redinesse of expansion and also of its exemtion
from freezing. But he nott thinking those sufficient Reasons
explaind a theory he had of their vsefulnessin that Instrument
Deduced from some chymicall ph principles of his owne wherby
he Indeauourd to shew the reason of all the appearances.

mr. Abraham Hill Queryd from what cause it was that the ^/& tube/ being well
Purged of Air and the experiment being made wth. great care, the
had been found to stand to the Height of 70 inches contrary to
the receiud theory of the Grauitation of the Air.
to wch. mr. Hook answered that though by such diligence & care as he had men
tioned he had made the mercury to stand to that height yet euen then if
any considerable iog or shake were giuen to the .. tube in wch. the was
suspended the would Leaue the top of the tube & fall to the height of 30
inches or thereabout according as thestandard of the
was at that time. and added that this 2d.
suspension Depended vpon a second cause

Ref: CELL/RS/HF_119  © Centre for Editing Lives and Letters