Diurnal Tides on the Coasts of Ireland. 135 



and, substituting the following values, 



2iT . 27r 



27r 



* 86400' * 89280' 



7?? = 



25000 X 5280' 



we find, expressing the depth in miles, 



Acceleration of Lunar Tide _13'815 — A .^. 



Acceleration of Solar Tide ~ 12-938 - k' ^ ^ 



It is by the aid of this equation that the depths of the sea given in the 

 Table are calculated. These depths agree remarkably well together, and 

 although they diflfer considerably from the depths found from the Heights of 

 the Lunar and Solar Tides, we shall find them confirmed in a remarkable 

 manner by the depths of the sea, deducible from the Age of the Lunar Diurnal 

 Tide. 



The progress of the Lunar and Solar Diurnal Tide Wave round the island 

 is seen from the column of Establishments, from which it appears that the 

 Diurnal Tide Wave approaches Ireland from the west, and, flowing round the 

 island north and south, enters the Irish Sea at both extremities ; the two waves 

 meeting off the coast of Down, in the case of the Lunar Tide ; and further 

 north, off the Antrim coast, in the case of the Solar Tide. 



The direction of the Lunar Tide Wave before it enters the Channel may be 

 thus ascertained ; let 



The distance from Caherciveen to Bunown = a, 



„ „ Dunmore =6, 



„ „ Portrush = c. 



The difference of Establishments at Caherciveen and Bunown = a, 

 „ „ Caherciveen and Dunmore = /3, 



„ „ Caherciveen and Portrush = y, 



The angle between direction of Tide and Bunown . . . = A, 

 „ „ Dunmore . . . = B, 



„ „ Portrush . . . = C, 



It is easy to see that we have the following equations, 



