Hydraulic Architecture, Volume 2, Part 2

...as it were, Switzerland from the mainland of Italy.

César d’Arcons claims that in the Archipelago The Aegean Sea., at the Strait of Chalcedon original: "détroit de Calcédoine"; here Bélidor refers to the Euripus Strait, which separates Greece from the island of Negroponte The island of Euboea., if one observes the different movements of the waters of this strait from a suitable position, one will see them likewise enter at the same time through both ends and meet opposite this spot after having taken 6 hours to join; that they then separate and return for another 6 hours to where they had come from, after which they enter all over again to begin the same maneuver, which occurs twice in 24 hours and 48 minutes. This author adds that the ancients, for want of having examined these different movements from the only place where one could judge them well, counted only 7 instead of 8; that as they attributed something marvelous to this number, they did not fail to seize upon it to peddle a thousand chimeras Fanciful or groundless stories. regarding this strait, although it had nothing that was not common with the Strait of Messina, and most others formed in the Ocean by islands situated near great coasts.

Another proof drawn from what is observed on the shores of the Adriatic Gulf. A sea must be at least 150 leagues wide, north and south, for the tides there to be perceptible.

601. Yet another proof that this sea flows and ebbs The rising and falling of the tide. from south to north and from north to south, and that the tides are stronger the more width it has in this direction, is that when it rises by 3 feet at Venice, it only rises by 2 at Ancona, by only one toward the middle of the length of the same gulf, and very little at Brindisi and Otranto, which are at its mouth, situated toward the middle of the 300 leagues A league is roughly 3 miles or 4.8 kilometers. of width that the Mediterranean Sea has from Venice to the coast of Africa.

It should be noted that if this sea has only very little flow and ebb on most of these coasts, it comes from its lack of extent from north to south, since the inequalities of the increase in tides correspond closely enough to the inequalities of its north-south width, which must be at least 150 leagues for the tides to be clearly perceptible during the times of the new and full moons.

Weak arguments of those who attribute the regular movements observed in the Mediterranean to the Ocean. If certain seas pla-

602. Those who wish to attribute the regular movements observed in parts of the Mediterranean solely to the tides of the Ocean say that during the flow, the waters passing through the Strait of Gibraltar, coming to strike against the coasts of Spain, are reflected toward the shore of Africa, and from there are sent back into the Gulf of Venice, where they cause by their pressure the flow that is felt there, which cannot take place in
Part II. Volume II.