Tides in the Mediterranean and Adjacent Seas 



439 



error in the phase of 4° and in the amplitude of 3 cm. Here also there was 

 agreement between the computed currents at the opening of the cross-sections 

 and the observed currents only as to the order of magnitude, but the phases 

 do not agree. Figure 187 gives the picture for the M 2 tide. The co-tidal lines 



FlG. 187. Co-tidal lines and amplitudes of the M 2 tide in the Gulf of Mexico (see Fig. 186). 



show a positive amphidromic point in the north-western section of the Gulf 

 with a strong crowding of the co-tidal lines in the north-south direction, so 

 that the tide comes close to a simple oscillation. Here also the co-oscillation 

 with the tide in front of the Strait of Florida seems to be the most important. 

 The independent tides by themselves would give a negative amphidromy, and 

 this might be the reason why the amphidromy of the co-oscillating tide appears 

 to be so little developed. 



18. The Tides of the Gulf of St. Lawrence 



The tidal picture of this adjacent sea has been given by Dawson (1920). 

 Current observations are available in sufficient quantity (Dawson 1907, 1913, 

 1920), so that nothing would prevent a complete hydrodynamical theory of 

 these tides. However, its orographical configuration is very intricate. In the 

 south-east it has a good communication with the ocean through the 56 nm 

 wide Cabot Strait ; in the north-east the narrow Strait of Belle Isle leads into 

 the Labrador Sea. In the north-west the Gulf is separated by Anticosti Island 

 from the St. Lawrence River estuary, and in the south-west Prince Edward 

 Island shields Northumberland Strait. These irregularities of the coastal con- 

 figuration on three sides make it difficult to compute accurately the conditions 

 of oscillation. 



Already Harris found that the essentially semi-diurnal tides of the Gulf can 

 be represented by an amphidromy rotating to the right which he assumes to 

 be formed by the effect of the rotation of the earth on the co-oscillating 

 tides coming through the Cabot Strait. Basing on the observations of 



