MR. G. I. TAYLOR ON TIDAL FRICTION IN THE IRISH SEA. 



11 



the velocities of the tidal streams at various states of the tide at various lightships 

 in the neighbourhood of the Arklow-Bardsey section. 



On inspecting the curves shown in that figure, it will be seen that the maximum 

 current is at about 3h. before H.W. at Dover. It is H.W. at Dover at llh. 7m. 

 full and change, and it is H.W. on the Arklow-Bardsey line at 8h. 10m.* full and 

 change. Hence it is H.W. on AB 3h. before H.W. at Dover, i.e., at the time of the 

 maximum tidal current. 



Since H.W. coincides with the time of maximum current, the difference in range at 

 spring tides between those at Arklow and those at Bardsey should be 2x57 feet 

 = 11 '4 feet. The measured range at Bardsey at spring tides is 15 feet, while that at 



Fig. 2. Curves showing the velocity of the tidal currents at three light ships in the South Channel 



to the Irish Sea at various states of the tide. 



Arklow is 4 feet. The difference, 11 feet, is almost exactly equal to the calculated 

 difference ll|- feet. 



The accuracy with which this calculation is verified by observation is very good 

 evidence that the sea actually slopes in the way we should expect from the current 

 measurements, that is to say, uniformly from Bardsey Island to Arklow. It is not 

 necessary, therefore, for our purpose to have actual tidal measurements in mid- 

 channel, though it is to be hoped that these conclusions will some day be tested by 

 observation. 



* See p. 15 later. 

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