Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/427

 other eminent aereal alteration that might occasion the same; of which disturbance of the Air we ought to make great account in other accidents, and to take it for a third and accidental cause, able to alter very much the observation of the effects depending on the secondary and more essential causes. And it is not to be doubted, but that impetuous windes, continuing to blow, for example, from the East, they shall retein the Waters and prohibit the reflux or ebbing; whereupon the second and third reply of the flux or tide overtaking the former, at the hours prefixed, they will swell very high; and being thus born up for some dayes, by the strength of the Winds, they shall rise more than usual, making extraordinary inundations.

We ought also, (and this shall serve for a seventh Probleme) to take notice of another cause of motion dependant on the great abundance of the Waters of great Rivers that discharge themselves into Seas of no great capacity, whereupon in the Straits or Bosphori that communicate with those Seas, the Waters are seen to run always one way: as it happeneth in the Thracian Bosphorus below Constantinople, where the water alwayes runneth from the Black-Sea, towards the Propontis: For in the said Black-Sea by reason of its shortnesse, the principal causes of ebbing and flowing are but of small force. But, on the contrary, very great Rivers falling into the same, those huge defluxions of water being to passe and disgorge themselves by the thethe [sic] straight, the * course is there very notable and alwayes towards the South. Where moreover we ought to take notice, that the said Straight or Channel, albeit very narrow, is not subject to perturbations, as the Straight of Scilla and Carybdis; for that that hath the Black-Sea above towards the North, and the Propontis, the Ægean, and the Mediterranean Seas joyned unto it, though by a long tract towards the South; but now, as we have observed, the Seas, though of never so great length, lying North and South, are not much subject to ebbings and flowings; but because the Sicilian Straight is situate between the parts of the Mediterrane distended for a long tract or distance from West to East, that is, according to the course of the fluxes and refluxes; therefore in this the agitations are very great; and would be much more violent between Hercules Pillars, in case the Straight of Gibraltar did open lesse; and those of the Straight of Magellanes are reported to be extraordinary violent.

This is what, for the present, cometh into my mind to say unto you about the causes of this first period diurnal of the Tide, and its various accidents, touching which, if you have any thing to offer, you may let us hear it, that so we may afterwards proceed to the other two periods, monethly and annual.