Galilei, Galileo - Discourse concerning the natation of bodies

Galilei, Galileo, Discourse concerning the natation of bodies, 1663

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hundred times as long as the other. Let the erroneous opinion o

thoſe therefore ceaſe, who hold that a Ship is better, and eaſter born
up in a great abundance of water, then in a leſſer quantity, (this was
believed by Ariſtotle in his Problems, Sect. 23, Probl. 2.) it being or
the contrary true, that its poſſible, that a Ship may as well float in
ten Tun of water, as in an Ocean.

A ſhip flotes as
well in ten Tun
of water as in an
Ocean.

A Solid ſpeci
fiaclly graver
than the water,
cannot be born
up by any quan
tity of it.

But following our matter, I ſay, that by what hath been hitherto
demonſtrated, we may underſtand how, that

One of the above named Solids, when more grave in ſpecie than the water,
can never be ſuſtained, by any whatever quantity of it.

For having ſeen how that the Moment wherewith ſuch a Solid
as grave in ſpecie as the water, contraſts with the Moment of any Maſs
of water whatſoever, is able to retain it, even to its totall Submerſion:
without its ever aſcending; it remaineth, manifeſt, that the water is
far leſs able to raiſe it up, when it exceeds the ſame in ſpecie: ſo,
that though you infuſe water till its totall Submerſion, it ſhall ſtill
ſtay at the Bottome, and with ſuch Gravity, and Reſiſtance to Eleva
tion, as is the exceſs of its Abſolute Gravity, above the Abſolute Gra
vity of a Maſs equall to it, made of water, or of a Matter in ſpecie
equally grave with the water: and, though you ſhould moreover
adde never ſo much water above the Levell of that which equalizeth
the Altitude of the Solid, it ſhall not, for all that, encreaſe the Preſſion
or Gravitation, of the parts circumfuſed about the ſaid Solid, by
which greater preſſion, it might come to be repulſed, becauſe, the
Reſiſtance is not made, but only by thoſe parts of the water, which
at the Motion of the ſaid Solid do alſo move, and theſe are thoſe
only, which are comprehended by the two Superficies equidiſtant to
the Horizon, and their parallels, that comprehend the Altitude of the
Solid immerged in the water.

I conceive, I have by this time ſufficiently declared and opened
the way to the contemplation of the true, intrinſecall and proper
Cauſes of diverſe Motions, and of the Reſt of many Solid Bodies in
diverſe Mediums, and particularly in the water, ſhewing how all ii
effect, depend on the mutuall exceſſes of the Gravity of the Movea
bles and of the Mediums: and, that which did highly import, re
moving the Objection, which peradventure would have begotter
much doubting, and ſcruple in ſome, about the verity of my Con
cluſion, namely, how that notwithſtanding, that the exceſs of the
Gravity of the water, above the Gravity of the Solid, demitted into
it, be the cauſe of its floating and riſing from the Bottom to the Sur
face, yet a quantity of water, that weighs not ten pounds, can raiſe

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