390 Tides in the Mediterranean and Adjacent Seas 



the possibility of independent tides and attempts to explain the existing ones 

 by an Atlantic wave penetrating through the Strait of Gibraltar into the 

 Mediterranean. Wegemann (1913, p. 555) has developed this theory and 

 tries to make it agree with the observed data through interferences between 

 the penetrating wave and the reflected wave on the Italian coasts and which 

 leads partly to standing waves. In the eastern Mediterranean basin he 

 assumes, like Harris (1904), an amphidromy contra solem around Crete, 

 which he thinks results from the superposition of the Atlantic wave penetrat- 

 ing through the Strait of Tunis with its reflection on the coasts of Syria. 



Sterneck (1913-15, see also, Defant, 1913, p. 361; 1916, p. 462; 1922) 

 attempted in several papers to explain the tidal phenomena of the Mediter- 

 ranean by computation based on hydrodynamics. He developed this theory 

 further and it agrees with the harmonic constants observed at coastal lo- 

 calities. He examines first the direct effect of the tide-generating forces for 

 each of the two Mediterranean basins, assuming that these basins are com- 

 pletely closed on all sides. The natural period is 5-96 h for the western basin 

 and 8-54 h for the eastern basin, and he finds in each basin a nodal line 

 placed almost exactly in the middle of the Mediterranean with establishments 

 of 3 h in the western and 9 h in the eastern part. 



The eastern basin has no other tidal components than this independent 

 tide. This seems astonishing, as it is connected with the other basins of the 

 Mediterranean (the Adriatic and Aegean Sea, and the Straits of Messina 

 and Tunis). However, Sterneck pointed out that, at the time of the syzygies 

 from 3 to 9h, the eastern basin receives from the Adriatic 131 km 3 , from 

 the Aegean Sea 35 1 km 3 of water, in all 48-2 km 3 , whereas during the same 

 time it loses 110 km 3 through the Strait of Messina, 41-9 km 3 through the 

 Strait of Tunis, totalling 52-9 km 3 , so that but for the small quantity of 

 4-7 km 3 the total water-mass of the eastern basin remains constant during 

 one tidal period. In first approximation the co-oscillating tides with the 

 other basins will be negligible compared to the independent tidal component. 



Sterneck gives an exceptional position to the Syrtis Minor, which features 

 small water depths and in its central part a considerable increase in tidal 

 ranges. He treats this region as a closed one, separating it from the water 

 masses in the eastern section of the Strait of Tunis, which is a rather arbi- 

 trary decision. It would seem more simple to regard the Syrtis Minor as 

 a bay extending from the estuary of Ras Kapudia (tidal range 22 cm) in the 

 north to a point a little west of Tripoli (tidal range 20 cm) in the south. The 

 free period of this region is about 6 h, so that v will be about | . This points 

 to a co-oscillation of the water-masses in this bay with the outer tides magni- 

 fied by resonance. It is for this reason that there are the great tidal ranges 

 of nearly 200 cm at Gabes and Skhirra. 



The western basin has, beside its independent tide, co-oscillating tides 

 with the Atlantic Ocean through the Strait of Gibraltar and, with the eastern 



