Archimedes Texts

207
sed to make its vibrations successively more and more frequent;
and consequently is able to bring a continual impediment to the
plummet C; and for a proof that this is so, if we do but observe
the thread A C, we shall see it distended not directly, but in an
arch; and if instead of the thread we take a chain, we shall dis
cern the effect more persectly; and especially removing the gra

vity C, to a considerable distance from the perpendicular A B, for
that the chain being composed of many loose particles, and each of
them of some weight, the arches A E C, and A F D, will appear
notably incurvated. By reason therefore, that the parts of the
chain, according as they are neerer to the point A, desire to make
their vibrations more frequent, they permit not the lower parts of
the said chain to swing so far as naturally they would: and by
continual detracting from the vibrations of the plummet C, they
finally make it cease to move, although the impediment of the air
might be removed.

The vibrations
of the same pen
dulum are made
with the same fre
quency, whether
they be small or
great.

The thread or
chain to which a
pendulum is fast
ned, maketh an
arch, and doth not
stretch it selfe
streight out in its
vibrations.

SAGR. The books are now come; here take them Simplicius,
and find the place you are in doubt of.

SIMP. See, here it is where he beginneth to argue against the
diurnal motion of the Earth, he having first confuted the annual.
Motus terræ annuus asserrere Copernicanos cogit conversionem e
jusdem quotidianam; alias idem terræ Hemisphærium continenter
ad Solem esset conversum obumbrato semper averso. [In English
thus:] The annual motion of the Earth doth compell the Co
pernicans to assert the daily conversion thereof; otherwise the
same Hemisphere of the Earth would be continually turned to
wards the Sun, the shady side being always averse. And so one
half of the Earth would never come to see the Sun.

SALV. I find at the very sirst sight, that this man hath not rightly
apprehended the Copernican Hypothesis, for if he had but taken
notice how he alwayes makes the Axis of the terrestrial Globe
perpetually parallel to it self, he would not have said, that one
half of the Earth would never see the Sun, but that the year
would be one entire natural day, that is, that thorow all parts of
the Earth there would be six moneths day, and six moneths night,
as it now befalleth to the inhabitants under the Pole, but let
this mistake be forgiven him, and let us come to what remai
neth.

SIMP. It followeth, Hanc autem gyrationem Terræ im
possibilem esse sic demonstramus. Which speaks in English thus:
That this gyration of the Earth is impossible we thus demonstrate.
That which ensueth is the declaration of the following figure,
wherein is delineated many descending grave bodies, and ascend
ing light bodies, and birds that fly too and again in the air, &c.