Chapter XII 



Tides in the Mediterranean 



and Adjacent Seas. Observations 



and Discussion 



We intend to give, in this chapter, a survey of the tidal phenomena of several 

 Mediterranean and adjacent seas, based on observations. We will only deal 

 with the principal, most important and characteristic features of the respective 

 seas. Furthermore, the attempts made to interpret these features will be 

 briefly outlined. For complete descriptions, we refer to the literature quoted. 



1. The Tides of the North Sea 



The first attempts to represent the tides of the North Sea in charts started 

 in the beginning of the last century. On these charts the tide wave penetrates 

 through the Strait of Dover and, from the north, through the wide opening 

 between Scotland and Norway. These were the first trials at all, after the 

 theory of the tides had been founded, to approach the tidal phenomenon 

 by means of geographical representations. Ever since, the tides of the North 

 Sea have remained a test for the various tidal theories (see Thorade, 1930. 

 p. 195). We can distinguish three periods in the development of the theory 

 of the North Sea tides. The first period includes Young, Whewell and Airy. 

 Young recognized that the tides of smaller ocean basins can hardly be a direct 

 effect of the tide-generating forces, but that the tide penetrates into these 

 basins from the open ocean. By drawing co-tidal lines (referred to the transit 

 of the moon) for the areas off the British Island, he was able to show the 

 penetration of the tidal wave into the North Sea from the north, as well as 

 from the English Channel. Whewell (1836, p. 289) has given a detailed map 

 with co-tidal lines for the North Sea (Fig. 152) in which he indicated the 

 presence of an amphidromic point in the Hoofden and suggested also a second 

 one in the Deutsche Bucht. Although he considered his first attempt at a co- 

 tidal chart as tentative, he recognized already that the tide wave progresses 

 at the English coast from north to south, at the Belgian and the Dutch coast 

 from south to north and at the German coast from west to east. He explained 

 these conditions as being the result of interferences of standing oscillations. 



