Hooke Folio
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188

or any other grosse fluid those proportions would hold very neer
yet, w In a medium wherein there was a resisting fluid body it
would not hold in any wise especially in those which had a consi
derable proportion of specifique Grauity to that of the
Descending body. Hence he said was the Reason why a down
feather being Lett fall in the air, would descend therein if it
were not Disturbed by an aequall Degree of velocity. But
on the contrary if the said feather were Let fall in a
medium whence all the air was exhausted and nothing but
A fluid ether left he affirmed the same would fall therein
as to sense wth the same /accelerated/ velocitys that a stone would doe in
the open air. this He affirmed he had formerly shewd to
his maiesty at whitehall. But that vpon the admitting of
the air into the space through wch. the feather was to
Descend the same was plainly seen to Descend wth an aequall
degree of velocity the whole space which was all the way very
slow. He further added that In Vacuo the Descent of all
bodys was aequally swift increasing continually its velocity
by a duplicate proportion to the time of continuance but
that in all grauitating mediums somewt. of that proportion
is impeded. Hence he affirmed that in the Expts. tryed from
the top of St. Paules steeple It was very plainly visible
that a Leaden ball would Descend faster then . . . one of the
same bignesse of wood, and that of wood faster then
one of cork. insoemuch that the heauiest would in that
Descent get neer 30 foot before the other at the bottom
He further added also that euen of Bullots of the same substance
the bigger would manifestly out run the lesse in their descent

As also that all mediums whatsoeuer had some Resistance to
the motion of bodys through them. and that euen those wch
had les Least, had yet a very considerable opposition to
a motion that were proportionally Accelerated. Hence
It was that Birds were able to susteine themselues in
the air, and that one might break the strongest oar
by swiftly striking it /against/ . . .. the water