Archimedes Texts

381
as one, that besides your being born, and having, for a long
time, dwelt in Venice, where the Tides are very notable for their
greatnesse, have also sailed into Syria, and, as an ingenuous and
apprehensive wit, must needs have made many Observations up
on this subject: whereas I, that could onely for a time, and that
very short, observe what happened in these extream parts of the
Adriatick Gulph, and in our Seas below about the Tyrrhene
shores, must needs take many things upon the relation of o
thers, who, for the most part, not very well agreeing, and con
sequently being very uncertain, contribute more of confusion
than confirmation to our speculations. Neverthelesse, from those
that we are sure of, and which are the principal, I think I am a
ble to attain to the true and primary causes; not that I pretend
to be able to produce all the proper and adequate reasons of
those effects that are new unto me, and which consequently I
could never have thought upon. And that which I have to say,
I propose only, as a key that openeth the door to a path never
yet trodden by any, in certain hope, that some wits more specu
lative than mine, will make a further progresse herin, and pene
trate much farther than I shall have done in this my first Disco
very: And although that in other Seas, remote from us, there may
happen several accidents, which do not happen in our Mediter
ranean Sea, yet doth not this invalidate the reason and cause that
I shall produce, if so be that it verisie and fully resolve the ac
cidents which evene in our Sea: for that in conclusion there can
be but one true and primary cause of the effects that are of the
same kind. I will relate unto you, therefore, the effects that I
know to be true, and assigne the causes thereof that I think
to be true, and you also, Gentlemen, shall produce such
others as are known to you, besides mine, and then we will
try whether the cause, by me alledged, may satisfie them
also.

I therefore affirm the periods that are observed in the fluxes
and refluxes of the Sea-waters to be three: the first and princi
pal is this great and most obvious one; namely, the diurnal, accor
ding to which the intervals of some hours with the waters flow and
ebbe; and these intervals are, for the most part, in the Mediter
rane from six hours to six hours, or thereabouts, that is, they for
six hours flow, and for six hours ebbe. The second period is
monethly, and it seemes to take its origen from the motion of
the Moon, not that it introduceth other motions, but only al
tereth the greatnesse of those before mentioned, with a notable
difference, according as it shall wax or wane, or come to the
Quadrature with the Sun. The third Period is annual, and is
seen to depend on the Sunne, and onely altereth the diurnal