420 Tides in the Mediterranean and Adjacent Seas 



a phase of about 310°. There is a second area with a nearly uniform phase 

 of about 150° between Western Borneo and Sumatra. At the end of the 

 Strait of Malacca there might be a small amphidromy rotating to the left, 

 with its center north of the Lingga Islands. It would seem that its area on 

 the Dietrich chart has been assumed too large. It is probably caused by the 

 interference of the tide wave progressing south-eastward through the Strait 

 of Malacca. 



Along the main canal, the phases and amplitudes show a pronounced, 

 outstretched amphidromy rotating to the left in the Java Sea with its center 

 near Bawean Island. From this centre to Southern Celebes (Macassar) many 

 co-tidal lines are crowded together in a small space, so that they form almost 

 a nodal line with a change of phase from 320° to 140°. The amphidromy 

 is particularly well indicated by the decrease of the amplitudes to 5 cm and 

 below, which in this area results in an almost diurnal tide. The canal section 

 of the Flores and Banda Sea has nearly uniform phases between 330° and 350°. 



Canal section 2 has again the phases at its opening of about 130° in the 

 north and 340° in the south, consequently again almost opposite phases, so 

 that with a natural period of about 12 h and v = 1, one nodal line should 

 occur in the middle, i.e. at the southern entrance into Strait Macassar. This 

 is exactly the point where there is a nodal line extending, from the amphidromy 

 in the Java Sea to Southern Celebes. In accordance with this interpretation, 

 the observations made in the Celebes Sea and in the entire Strait of Macassar 

 show phases near 130°. 



Canal section 3 also has the same phases at its openings. With an ap- 

 proximate natural period of 71 h and v = about 0-6, one nodal line can be 

 expected and, in fact, a dense crowding of the co-tidal lines is noticeable 

 near the group of islands extending from Celebes to Halmahera. 



On going over these rough outlines of a theory of the M 2 tide, in which 

 the independent tides have been neglected, one must admit that the charac- 

 teristic features of the theoretical tidal picture are in good agreement with 

 the observed facts. But only an accurate computation by the theory can show 

 how much the independent tides can change the picture. The influence of 

 the deflecting force of the rotation of the earth is probably small, inasmuch 

 as we have to deal with regions near the Equator. 



In the case of the diurnal tides, which appear to be very well developed 

 in this entire area, conditions are more complicated, although here the picture 

 of the co-tidal lines is simpler. The direct influence of the tide-generating 

 forces might be far more apparent with these partial tides, as the v values 

 for the two first canals come very close to the corresponding resonance values. 

 Thus, the superposition of the two components creates a picture of the co- 

 tidal lines which is not easy to disentangle. In the South China Sea the phase 

 over a large area (referred to Batavia) is 310°, then the co-tidal lines crowd 

 in the south-western section, and in the western section of the Java Sea there 



