§23.1Διὰ τί τὸ κῦμα οὐκ ἐπιγελᾷ ἐν τοῖς βαθέσι πελάγεσιν, ἀλλ’ ἐν τοῖς μικροῖς καὶ βραχέσιν;
Why is it that waves do not break (foam) in the deep open seas, but in narrow and shallow waters?
ἢ ὅτι τὸ μικρὸν ὑγρὸν φερόμενον μᾶλλον διαιρεῖται ὑπὸ τοῦ πνεύματος ἢ τὸ πολύ;
Is it because a small amount of water when in motion is more easily divided by the wind than a large amount?
§23.2Διὰ τί τὰ κύματα πρότερον φοιτᾷ ἐνίοτε τῶν ἀνέμων;
Why is it that waves sometimes arrive before the winds?
ἢ ὅτι πρὸς τῇ ἀρχῇ τοῦ πνεύματος ἡ θάλαττα ὠσθεῖσα πρώτη τὴν ἐχομένην ἀεὶ ταὐτὸν ποιεῖ;
Is it because the sea, pushed at the beginning of the wind, becomes the first and always produces the same effect on the adjacent part?
διόπερ οὔσης αὐτῆς συνεχοῦς καθάπερ μιᾷ πληγῇ συνεχεῖ πάσαις γίνεται.
Therefore, since the sea is continuous, the motion occurs to all waves as if by a single continuous blow.
τὸ δὲ ἐν ἑνὶ χρόνῳ γίνεται, ὥστε συμβαίνει τήν τε πρώτην καὶ τὴν ἐσχάτην ἅμα κινεῖσθαι.
And this happens in a single moment, so that it happens that both the first and the last waves move at the same time.
ὁ δὲ ἀὴρ οὐ πάσχει τοῦτο, ὅτι οὔτε ἐστὶν ἓν σῶμα συνεχές, τῷ πολλὰς πάντοθεν ἀντικρούσεις λαμβάνειν, αἳ πολλάκις κωλύουσι τὴν πρώτην καὶ νεανικωτάτην κίνησιν, τήν τε θάλασσαν οὐ ποιοῦσι τοῦτο διὰ τὸ βαρυτέραν καὶ δυσκινητοτέραν αὐτοῦ εἶναι.
But the air does not experience this, because it is not a single continuous body, owing to its receiving many counter-shocks from all sides, which often prevent the first and most vigorous motion, and because [these counter-shocks] do not do this to the sea because it is heavier and more difficult to move than the air.
§23.3Διὰ τί τὰ πλοῖα γέμειν δοκεῖ μᾶλλον ἐν τῷ λιμένι ἢ ἐν τῷ πελάγει, καὶ θεῖ δὲ θᾶττον ἐκ τοῦ πελάγους πρὸς τὴν γῆν ἢ ἀπὸ τῆς γῆς εἰς τὸ πέλαγος;
Why is it that ships seem to carry more load (sink deeper) in the harbor than in the open sea, and sail faster from the open sea toward the land than from the land into the open sea?
ἢ ὅτι τὸ πλέον ὕδωρ ἀντερείδει μᾶλλον ἐκ τοῦ ὀλίγου, ἐν δὲ τῷ ὀλίγῳ δέδυκεν διὰ τὸ κρατεῖν αὐτοῦ μᾶλλον;
Is it because a larger body of water pushes back more than a small amount, whereas in a small amount of water the ship sinks deeper because it overcomes the water more?
ὠθεῖ γὰρ κάτωθεν τὸ ὕδωρ ἄνω.
For the water pushes upward from below.
ἐν μὲν οὖν τῷ λιμένι ὀλίγη ἐστὶν ἡ θάλασσα, ἐν δὲ τῷ πελάγει βαθεῖα.
In the harbor, then, the sea is small, but in the open sea it is deep.
ὥστε καὶ ἄγειν πλέον δόξει ἐν τῷ λιμένι καὶ κινήσεται χαλεπώτερον διὰ τὸ δεδυκέναι μᾶλλον καὶ ἧττον ἀντερείδειν τὸ ὕδωρ.
Consequently, the ship will both seem to carry more load in the harbor and will move with greater difficulty because it has sunk deeper and the water pushes back less.
ἐν τῷ πελάγει δὲ τἀναντία τούτων ἐστίν.
In the open sea, the opposite of these things occurs.
§23.4Διὰ τί, ὅταν τι ῥιφθῇ εἰς τὴν θάλατταν κυμαίνουσαν, οἷν ἡ ἄγκυρα, γαλήνη γίνεται;
Why is it that when something is thrown into the wavy sea, such as an anchor, a calm ensues?
ἢ διότι ἵσταται ἡ θάλαττα τῷ φερομένῳ, μεθ’ οὗ ἀὴρ συγκαταφέρεται, ὃς ἐπ’ εὐθείας κάτω φερόμενος καὶ ἐνταῦθα ἐπισπασθεὶς συνεπισπᾶται τὸ ἐκ πλαγίου κινοῦν τὴν θάλατταν;
Is it because the sea is stilled by the falling object, with which air is carried down together, which being carried straight down and drawn in there, draws down with it that which moves the sea from the side?
ὁ δὲ κλύδων τῆς θαλάττης οὐκ ἄνωθεν κάτω γίνεται ἀλλ’ ἐπιπολῆς· οὗ λήξαντος γαλήνη γίνεται.
For the swelling of the sea does not occur from above downward but on the surface; when this ceases, a calm ensues.
ἔτι συνιοῦσα ἡ θάλασσα εἰς τὰ διαστάντα τῷ φερομένῳ δίνην ποιεῖ.
Moreover, the sea, coming together into the gap opened by the falling object, produces a vortex.
ἡ δὲ δίνη κύκλῳ φέρεται.
And the vortex moves in a circle.
ἐπεὶ δὲ ἡ εὐθεῖα τοῦ κύκλου κατὰ σημεῖον ἅπτεται, τὰ δὲ κύματα ἐπ’ εὐθείας λοξῆς φέρεται, συμβαίνοι ἂν αὐτὰ τοῦ ἐξωτάτου τῆς δίνης κατὰ σημεῖον ἅπτεσθαι, διά τε τὰ εἰρημένα καὶ διὰ τὴν τῆς δίνης φοράν, ἢ προσιοῦσα ἀπωθεῖται αὐτά.
Since a straight line touches a circle at a single point, and the waves are carried along an oblique straight line, it would happen that they touch the outermost part of the vortex at a single point, both because of the aforementioned reasons and because of the motion of the vortex, or else the vortex pushes them away as they approach.
ἀκύμου δὲ ὄντος τοῦ κατ’ αὐτὴν τόπου, γαλήνην ἐν τῇ ῥήξει αὐτῆς συμβαίνει γίνεσθαι, ὅτι συγκαταβὰς ὁ ἀὴρ τῷ ἐνεχθέντι κάτω, ἀναφερόμενος καὶ ὠθῶν ἄνω τὴν θάλατταν καθάπερ πομφολυγοῖ αὐτήν· ἡ γὰρ πομφόλυξ ὑγροῦ ὑπ’ ἀέρος κάτωθεν ἀνωθουμένου ἐστίν.
And since the place where the vortex is has no waves, a calm happens to occur in its breach, because the air which went down together with the object carried below, on rising and pushing the sea upward, makes it foam as if into bubbles; for a bubble is a liquid pushed upward from below by air.
πομφόλυξ δὲ πᾶσα λεία καὶ γαληνός ἐστιν.
And every bubble is smooth and calm.
σημεῖα δὲ τῶν εἰρημένων ἐστί· μετέωρος γὰρ ἡ κατὰ τὸ ἐνεχθὲν κάτω θάλαττα τῆς πέριξ γίνεται μικρὸν ὕστερον.
There are proofs of what has been said: for the sea at the place of the object carried below becomes higher than the surrounding sea a little later.
§23.5Διὰ τί ἐνίοτε πλοῖα θέοντα ἐν τῇ θαλάττῃ εὐδίας καταπίνεται καὶ ἀφανῆ γίνεται, ὥστε μηδὲ ναυάγιον ἀναπλεῖν;
Why is it that sometimes ships sailing on the sea in fair weather are swallowed up and disappear, so that not even any shipwrecked debris floats to the surface?
ἢ ὅταν ἀντρώδης τόπος ἐν τῇ ὑπὸ τὴν θάλατταν γῇ ῥαγῇ, ἅμα εἰς τὴν θάλατταν καὶ ἔσω ἀκολουθεῖ τῇ τοῦ πνεύματος φορᾷ;
Is it because when a cavernous place in the ground under the sea ruptures, the sea is at the same time drawn inward following the flow of the wind (air current)?
ὁμοίως δὲ καὶ πάντη φερομένη κύκλῳ φέρεται κάτω.
Similarly, being carried from all sides, it is carried downward in a circle.
τοῦτο δέ ἐστι δῖνος.
And this is a vortex.
τὰ δὲ περὶ Μεσήνην ἐν τῷ πορθμῷ πάσχει μὲν τοῦτο διὰ τὸν ῥοῦν (γίνονται γὰρ αἱ δῖναι ὑπὸ τούτου) καὶ καταπίνεται εἰς βυθὸν διὰ ταῦτά τε, καὶ ὅτι ἡ θάλαττα βαθεῖά τε καὶ ἡ γῆ ὕπαντρος μέχρι πόρρω.
The places around Messene in the strait experience this because of the current (for the vortices are produced by this) and are swallowed up into the depth because of these things, and because the sea is deep and the ground underneath is cavernous for a long distance.
φέρουσιν οὖν εἰς ταῦτα ἀποβιαζόμεναι αἱ δῖναι· διὸ οὐκ ἀναπλεῖ αὐτόθι τὰ ναυάγια.
The vortices, therefore, carry objects into these caverns by force; therefore shipwrecked debris does not float up there.
ὁ δὲ ῥοῦς γίνεται, ὅταν παυσαμένου τοῦ προτέρου ἀντιπνεύσῃ ἐπὶ τῆς θαλάττης ῥεούσης τῷ προτέρῳ πνεύματι, μάλιστα δὲ ὅταν νότος ἀντιπνεύσῃ.
Now the current occurs when, after the former wind has ceased, a wind blows in the opposite direction against the sea which is still flowing from the former wind, and especially when a south wind blows in the opposite direction.
ἀντιπνέοντα γὰρ ἀλλήλοις τὰ ῥεύματα παρεκθλίβεται ὥσπερ ἐν τοῖς ποταμοῖς, καὶ γίνονται αἱ δῖναι.
For currents blowing against one another are squeezed out sideways, just as in rivers, and vortices are produced.
φέρεται δὲ ἑλιττομένη ἡ ἀρχὴ τῆς κινήσεως ἄνωθεν ἰσχυρὰ οὖσα.
And the beginning of the motion is carried in a spiral from above, being powerful.
ἐπεὶ οὖν εἰς πλάγιον οὐκ ἔστιν ὁρμᾶν (ἀντωθεῖται γὰρ ὑπ’ ἀλλήλων), ἀνάγκη εἰς βάθος ὠθεῖσθαι, ὥστε καὶ ὃ ἂν ληφθῇ ὑπὸ τῆς δίνης, ἀνάγκη συγκαταφέρεσθαι.
Since, therefore, it is not possible to rush sideways (for they push back against one another), it is necessary to be pushed into the depth, so that whatever is caught by the vortex must also be carried down with it.
διὸ ἀνάσιμα τὰ πλοῖα ποιοῦνται· ἤδη γὰρ ὀρθόν ποτε μνημονεύεται καταποθέν.
For this reason, they make ships with upturned bows; for indeed it is remembered that once a ship was swallowed up upright.