Archimedes Texts

400
without diminishing or increasing it according to the precise rate
of its diminishing or increasing in its Vessel. Because therefore

that in the conservation and retention of the impetus before con
ceived, the disobedience to a new augmentation or diminution of
motion consisteth, that moveable that shall be most apt for such
a retention, shall be also most commodious to demonstrate the
effect that followeth in consequence of that retention. Now how
much the Water is disposed to maintain such a conceived agita
tion; though the causes cease that impress the same, the experi
ence of the Seas extreamly disturbed by impetuous Winds shew
eth us; the Billows of which, though the Air be grown calm, and
the Wind laid, for a long time after continue in motion: As the
Sacred Poet pleasantly sings,

And that long continuing rough after a storm, dependeth on

the gravity of the water: For, as I have elsewhere said, light bo
dies are much easier to be moved than the more grave, but yet
are so much the less apt to conserve the motion imparted, when
once the moving cause ceaseth. Whence it comes that the Aire,
as being of it self very light and thin, is easily mov'd by any very
small force, yet it is withall very unable to hold on its motion,
the Mover once ceasing. Therefore, as to the Aire which envi
rons the Terrestrial Globe, I would fay, that by reason of its
adherence, it is no lesse carried about therewith then the Water;
and especially that part which is contained in its vessels; which

vessels are the valleys enclosed with Mountains. And we may
with much more reason affirm that this same part of the Air is
carried round, and born forwards by the rugged parts of the
Earth, than that the higher is whirl'd about by the motion of the
Heavens, as ye Peripateticks maintain.

Light bodies easier
to be moved than
beavy, but less aut
to conserve the mo
tion.

Its more rational
that the Air be
commoved by the
rugged surface of
the Earth than
by the Celestial
motion.

What hath been hitherto spoken, seems to me a sufficient an

swer to the allega ion of Simputius; yet nevertheless with a new
instance and solution, founded upon an admirable experiment, I
will superabundantly satisfie him, and confirm to Sagredus the
mobility of the Earth. I have told you that the Air, and in par
ticular that part of it which ascendeth not above the tops of the
highest Mountains, is carried round by the uneven parts of the
Earths surface: from whence it should seem, that it must of con
sequence come to passe, that in case the superficies of the Earth
were not uneven, but smooth and plain, no cause would remain
for drawing the Air along with it, or at least for revolving it with
so much uniformity. Now the surface of this our Globe, is not
all craggy and rugged, but there are exceeding great tracts very