SVPPOSITION II.
It is ſuppoſed that thoſe Solids which are moved up
wards, do all aſcend according to the Perpendicular
which is produced thorow their Centre of Gravity.
wards, do all aſcend according to the Perpendicular
which is produced thorow their Centre of Gravity.
COMMANDINE.
And thoſe which are moved downwards, deſcend, likewiſe, according to the Perpendicular
that is produced thorow their Centre of Gravity, which he pretermitted either as known,
or as to be collected from what went before.
that is produced thorow their Centre of Gravity, which he pretermitted either as known,
or as to be collected from what went before.
NIC. For underſtanding of this ſecond Suppoſition, it is requiſite to take notice
that every Solid that is lighter than the Liquid being by violence, or by ſome other
occaſion, ſubmerged in the Liquid, and then left at liberty, it ſhall, by that which
hath been proved in the ſixth Propoſition, be thruſt or born up wards by the Liquid,
and that impulſe or thruſting is ſuppoſed to be directly according to the Perpendi
cular that is produced thorow the Centre of Gravity of that Solid; which Per
pendicular, if you well remember, is that which is drawn in the Imagination
from the Centre of the World, or of the Earth, unto the Centre of Gravity of
that Body, or Solid.
that every Solid that is lighter than the Liquid being by violence, or by ſome other
occaſion, ſubmerged in the Liquid, and then left at liberty, it ſhall, by that which
hath been proved in the ſixth Propoſition, be thruſt or born up wards by the Liquid,
and that impulſe or thruſting is ſuppoſed to be directly according to the Perpendi
cular that is produced thorow the Centre of Gravity of that Solid; which Per
pendicular, if you well remember, is that which is drawn in the Imagination
from the Centre of the World, or of the Earth, unto the Centre of Gravity of
that Body, or Solid.
RIC. How may one find the Centre of Gravity of a Solid?
NIC. This he ſheweth in that Book, intituled De Centris Gravium, vel de Æqui
ponderantibus; and therefore repair thither and you ſhall be ſatisfied, for to declare
it to you in this place would cauſe very great confuſion.
ponderantibus; and therefore repair thither and you ſhall be ſatisfied, for to declare
it to you in this place would cauſe very great confuſion.
RIC. I underſtand you: ſome other time we will talk of this, becauſe I have
a mind at preſent to proceed to the laſt Propoſition, the Expoſition of which ſeemeth
to me very confuſed, and, as I conceive, the Author hath not therein ſhewn all
the Subject of that Propoſition in general, but only a part: which Propoſition
ſpeaketh, as you know, in this form.
a mind at preſent to proceed to the laſt Propoſition, the Expoſition of which ſeemeth
to me very confuſed, and, as I conceive, the Author hath not therein ſhewn all
the Subject of that Propoſition in general, but only a part: which Propoſition
ſpeaketh, as you know, in this form.
PROP. VIII. THEOR. VIII.
A
If any Solid Magnitude, lighter than the Liquid, that
hath the Figure of a Portion of a Sphære, ſhall be
hath the Figure of a Portion of a Sphære, ſhall be
demitted into the Liquid in ſuch a manner as that
the Baſe of the Portion touch not the Liquid, the
Figure ſhall ſtand erectly, ſo, as that the Axis of
the ſaid Portion ſhall be according to the Perpen
dicular. And if the Figure ſhall be inclined to any
ſide, ſo, as that the Baſe of the Portion touch the
Liquid, it ſhall not continue ſo inclined as it was de
mitted, but ſhall return to its uprightneſs.