Archimedes Texts

413
that I fear I shall have but a small part of it left free and disin
gaged, to apply to the principal matter that is treated of, and
which of it self is but even too obscure and intricate: So that
I intreat you to vouchsafe me, having once dispatcht the business
of the ebbings and flowings, to do this honour to my house (and
yours) some other dayes, and to discourse upon the so many other
Problems that we have left in suspence; and which perhaps are
no less curious and admirable, than this that hath been discussed
these dayes past, and that now ought to draw to a con
clusion.

SALV. I shall be ready to serve you, but we must make more
than one or two Sessions; if besides the other questions reserved
to be handled apart, we would discusse those many that pertain
to the local motion, as well of natural moveables, as of the reject
ed: an Argument largely treated of by our Lyncean Accade
mick. But turning to our first purpose, where we were about to
declare, That the bodies moving circularly by a movent virtue,
which continually remaineth the same, the times of the circula
tions were prefixt and determined, and impossible to be made
longer or shorter, having given examples, and produced experi
ments thereof, sensible, and feasible, we may confirm the same
truth by the experiences of the Celestial motions of the Planets;
in which we see the same rule observed; for those that move by
greater Circles, confirm longer times in passing them. A most
pertinent observation of this we have from the Medicæan Pla
nets, which in short times make their revolutions about Jupiter:
Insomuch that it is not to be questioned, nay we may hold it for
sure and certain, that if for example, the Moon continuing to be
moved by the same movent faculty, should retire by little and
little in lesser Circles, it would acquire a power of abreviating
the times of its Periods, according to that Pendulum, of which in
the course of its vibrations, we by degrees shortned the cord, that
is contracted the Semidiameter of the circumferences by it passed.
Know now that this that I have alledged an example of it in the
Moon, is seen and verified essentially in fact. Let us call to mind,
that it hath been already concluded by us, together with Coperni-

cus, That it is not possible to separate the Moon from the Earth,
about which it without dispute revolveth in a Moneth: Let us
remember also that the Terrestrial Globe, accompanyed alwayes
by the Moon, goeth along the circumference of the Grand Orb
about the Sun in a year, in which time the Moon revolveth about
the Earth almost thirteen times; from which revolution it follow
eth, that the said Moon sometimes is found near the Sun; that is,
when it is between the Sun and the Earth, and sometimes
much more remote, that is, when the Earth is situate between