Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/410

 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 upon 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 others, who, for the most part, not very well agreeing, and consequently 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 able 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 speculative than mine, will make a further progresse herin, and penetrate much farther than I shall have done in this my first Discovery: And although that in other Seas, remote from us, there may happen several accidents, which do not happen in our Mediterranean Sea, yet doth not this invalidate the reason and cause that I shall produce, if so be that it verifie and fully resolve the accidents 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 principal is this great and most obvious one; namely, the diurnal, according to which the intervals of some hours with the waters flow and ebbe; and these intervals are, for the most part, in the Mediterrane 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 altereth 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