Diurnal Tides on the- Coasts of Ireland. 



85 



PoETRDSH. — Table F. 



Difference of Observed and Calculated Times of VaniMng of Diurnal Tide at Portrush, at Low 



Water, expressed in Litiiar Days. 

 Age of Lunar Tide = 4'' 19''. 



The agreement of the Observed and Calculated Tides, shown in Tables a, b, 

 c, D, E is very good ; but the differences in Table f are very great; they do not! 

 however, vitiate the accuracy of our Tidal Constants for Portrush, and pro- 

 bably owe their origin to the fact that the Diurnal Tide at Low Water at this 

 station was so small in amount, that a very slight error of Observation would 

 produce a considerable error in the Time of Vanishing. The agreement be- 

 tween Theory and Observation, as respects the Height of the Diurnal TiJe at 

 Low Water, is excellent. 



