A DISCOVRSE
Preſented to the Moſt Serene DON COSIMO II.
GREATDUKE of TUSC ANY:
CONCERNING
The Natation of BODIES Upon, or Submerſion
In, the WATER.
Preſented to the Moſt Serene DON COSIMO II.
GREATDUKE of TUSC ANY:
CONCERNING
The Natation of BODIES Upon, or Submerſion
In, the WATER.
Conſidering (Moſt Serene Prince) that the
publiſhing this preſent Treatiſe, of ſo
different an Argument from that which
many expect, and which according to the
intentions I propoſed in my ^{*} Aſtronomi
call Adviſo, I ſhould before this time
have put forth, might peradventure make
ſome thinke, either that I had wholly
relinquiſhed my farther imployment
about the new Celeſtiall Obſervations,
or that, at leaſt, I handled them very
remiſſely; I have judged fit to render an account, aſwell of my
deferring that, as of my writing, and publiſhing this treatiſe.
publiſhing this preſent Treatiſe, of ſo
different an Argument from that which
many expect, and which according to the
intentions I propoſed in my ^{*} Aſtronomi
call Adviſo, I ſhould before this time
have put forth, might peradventure make
ſome thinke, either that I had wholly
relinquiſhed my farther imployment
about the new Celeſtiall Obſervations,
or that, at leaſt, I handled them very
remiſſely; I have judged fit to render an account, aſwell of my
deferring that, as of my writing, and publiſhing this treatiſe.
His Nuncio Sl
derio.
derio.
As to the firſt, the laſt diſcoveries of Saturn to be tricorporeall, and
of the mutations of Figure in Venus, like to thoſe that are ſeen in the
Moon, together with the Conſequents depending thereupon, have
not ſo much occaſioned the demur, as the inveſtigation of the times
of the Converſions of each of the Four Medicean Planets about
piter, which I lighted upon in April the year paſt, 1611, at my being in
Rome; where, in the end, I aſſertained my ſelfe, that the firſt and neereſt
to Jupiter, moved about 8 gr. & 29 m. of its Sphere in an houre,
ing its whole revolution in one naturall day, and 18 hours, and almoſt
an halfe. The ſecond moves in its Orbe 14 gr. 13 min. or very neer,
in an hour, and its compleat converſion is conſummate in 3 dayes, 13
hours, and one third, or thereabouts. The third paſſeth in an hour,
2 gr. 6 min. little more or leſs of its Circle, and meaſures it all in 7
dayes, 4 hours, or very neer. The fourth, and more remote than the
reſt, goes in one houre, o gr 54 min. and almoſt an halfe of its Sphere,
and finiſheth it all in 16 dayes, and very neer 18 hours. But
cauſe the exceſſive velocity of their returns or reſtitutions, requires a
moſt ſcrupulous preciſeneſſe to calculate their places, in times paſt
of the mutations of Figure in Venus, like to thoſe that are ſeen in the
Moon, together with the Conſequents depending thereupon, have
not ſo much occaſioned the demur, as the inveſtigation of the times
of the Converſions of each of the Four Medicean Planets about
piter, which I lighted upon in April the year paſt, 1611, at my being in
Rome; where, in the end, I aſſertained my ſelfe, that the firſt and neereſt
to Jupiter, moved about 8 gr. & 29 m. of its Sphere in an houre,
ing its whole revolution in one naturall day, and 18 hours, and almoſt
an halfe. The ſecond moves in its Orbe 14 gr. 13 min. or very neer,
in an hour, and its compleat converſion is conſummate in 3 dayes, 13
hours, and one third, or thereabouts. The third paſſeth in an hour,
2 gr. 6 min. little more or leſs of its Circle, and meaſures it all in 7
dayes, 4 hours, or very neer. The fourth, and more remote than the
reſt, goes in one houre, o gr 54 min. and almoſt an halfe of its Sphere,
and finiſheth it all in 16 dayes, and very neer 18 hours. But
cauſe the exceſſive velocity of their returns or reſtitutions, requires a
moſt ſcrupulous preciſeneſſe to calculate their places, in times paſt