ON THE COASTS OF IRELAND. 



35 



The numbers in this table present several subjects for our consideration. 



First, it is to be remarked that the difference between the numbers of the second 

 and third columns corresponds to the number in the last column of the table on 

 page 30 (it is, in fact, the double of that number) ; but the exhibition of the numbers 

 in this form serves, in some instances, to point out their origin more distinctly. At 

 Limerick, for instance, it appears that a large tide produces less effect on the low- 

 water than on the high water ; and the reason evidently is, that the height of low 

 water there depends more upon the freshwater current of the river Shannon, than 

 upon the state of the water in the sea, whereas the height of high water depends 

 mainly on the sea. The same explanation applies at New Ross and at Passage West. 

 It does not however apply to Mullaghmore, Port Rush, Ballycastle, or Glenarm ; nor, 

 with perfect certainty, to Carrowkeel. I must refer to Section X. and some of the 

 succeeding sections, for a statement of the laws of the individual tides at these places ; 

 and shall only remark here, that much remains to be done with the theoretical treat- 

 ment of the motion of waves, before the tides on the north-eastern coast can be fully 

 explained. 



S 

 The next column which deserves particular attention is that for ^ • From the 



agreement among the numbers at the littoral stations on the western coast (Kilbaha, 

 Casleh Bay, Galway, Old Head, Mullaghmore), it seems certain that the value of 



vj , in this part of the Atlantic, is pretty exactly 0*42. At Brest, in a position equally 



f2 



