Tides in the Mediterranean and Adjacent Seas 417 



part of the component of the second kind, on the contrary, has a substantial 

 range, i.e. the water-masses co-oscillate vigorously with the independent tide 

 in the Gulf of Oman. The nodal lines of this pseudo co-oscillating tide co- 

 incide with those of the real co-oscillating tide; however both standing waves 

 have a phase difference of 3' h. 



The superposition of all these components gives the tides of the entire 

 area of oscillation. To this has to be added the effect of the deflecting force 

 of the rotation of the earth, which transforms the nodal lines into amphi- 

 dromies contra solem; these, however, are very well developed, because large 

 amplitudes over small depths command great velocities in the horizontal 

 displacements. The theoretical picture resulting from the superposition of 

 the longitudinal and transverse oscillations, does not deviate very much from 

 that of Fig. 175 neither as to phases nor as to ranges, so that the theory in 

 question can be considered to give a satisfactory explanation of the tides 

 of this adjacent sea. A more detailed investigation must be postponed until 

 such time when we have a sufficient number of harmonic constants of coastal 

 localities. It should be mentioned that frictional influences have not been 

 taken into account by this theory. In view of the small depths this omission 

 might perhaps not be justified. 



As the natural period of the Gulf lies close to 24 h, it is to be expected 

 that the diurnal tides are well developed. For these diurnal tides v is about 

 0-95, and the co-oscillating tide of the diurnal tides will have a nodal line 

 somewhere in the centre of the. Persian Gulf and will show in the antinodes 

 amplitudes which might be quite large. This explains that, in the Persian 

 Gulf, and particularly in the vicinity of the nodal lines of semi-diurnal tides, 

 the tides become almost of the diurnal type. In this case more and newer 

 values of the harmonic constants for adequately situated localities will give 

 a better insight. 



12. The Tides of the East Indian Archipelago 



The only description of the tidal phenomena in this entangled system of 

 straits in the East Indian Archipelago has been given by van der Stok (1897, 

 1910, 1911, p. 354). Thanks to him, the harmonic constants of a very great 

 number of coastal localities in the Indonesian Archipelago are known, so that 

 there is a good basis for explaining the tidal phenomena. However, it has 

 hitherto not been attempted to make an accurate hydrodynamical investiga- 

 tion based on modern methods. A description of the tidal picture has been 

 given by Krummel (1911, vol. II, p. 384), in which he makes reference to 

 charts of the co-tidal lines of the M 2 and K x tide designed by him. He bases 

 himself entirely on the viewpoint that the tides penetrate as progressive waves 

 from the open ocean into the various basins, and that they travel according 

 to the depths and that by mutual interferences they create the actual tidal 

 picture. We wish to direct the attention to the more recent charts of Van 



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