Diurnal Tides on the Coasts of Ireland. 



133 



780' 



and k = 5-07 miles. 



The mean depth of the sea here found agrees with that inferied from the 

 Diurnal Observations, and is only half that deduced, by me, from Mr. Airy's 

 Semidiurnal Observations, which, however, accord better with the mean depth 

 deducible from the Lunitidal and Solitidal Diurnal Intervals, and from the Age 

 of the Lunar Diurnal Tide, as will be shown presently. 



2. — The Lunitidal and Solitidal Intervals. 



If we place the Lunitidal and Solitidal Intervals in a Table, arranged in the 

 order of the Atlantic and Channel Stations, we obtain the following results: — 



Diurnal Tidal Intervals and Establishments. 



The last two columns of this Table express the Interval from the Lunar 

 or Solar passage of the Greenwich Meridian to High Water, at each Station ; 

 they are formed by adding the longitude, in time, of each Station to the Tidal 

 Intervals. 



It is possible, from Mr. Airy's Theory of Tides with Friction, to deduce the 

 mean depth of the sea from the preceding Table of Tidal Intervals, and the 

 results of this calculation, although different from the; depth deduced from 

 the Heights, are consistent with each other, and well worthy of attention. 



According to the Theory of Tide Waves without friction. Low Water should 

 oc;cur at the time of meridian passage of the luminary ; in consequence of 



