ON THE COASTS OF IRELAND. 



10: 



Section XIII. — Estahlishment of each port, as deduced from the time of majcimum of 

 the first periodical term in the analysis of individual tides. 



The preceding operations having' made it sufficiently clear that the age of the tide 

 differs little from two days, it is proper now to refer all the phenomena of the tide 

 to an epoch two days earlier than the observation. A process is therefore adopted in 

 this section differing in a trifling degree from that in Section VII. The times are 

 taken at which the moon's hour-angle fiom the sun was 0'', 6^, 12'*, 18'', and two days 

 are added to these times : the resulting times are June 24, 9^ July 2, 20^^, July 9, 19\ 

 July 16, 21'', July 23, 23^ August 1, 16'', August 8, 4'', August 15, 5'', August 22, 16''. 

 These times are assumed to divide the large lunitidal intervals from the small ones. 

 For the lunitidal intervals at the high waters of the First Division, the moon's time 

 of Greenwich transit is taken for that transit which precedes the high water by two 

 days and a few hours ; for the high waters of the Second Division the moon's time of 

 Greenwich lower transit is interpolated. Comparing these times of transit with the 

 times of high water in the formulae of Section X., the lunitidal intervals correspond- 

 ing to lunar transits two days earlier are found. The means of these are taken for 

 the groui>s separated by the times specified above. Then, the means of the large and 

 the small lunitidal intervals being adopted as the mean interval, a correction of !'» 

 41°' is applied subtractively, to reduce the interval after moon's transit two days pre- 

 vious, to the interval after moon's transit on the same day as the tide (l'' 41™ being 

 the difference between two solar days and two lunar days). The result is contained 

 in the following Table. 



Station. 



Kilbaha 



Kilrush 



Foynes Island. , . 



Limerick 



Casleh Bay 



Gahvay 



Old Head 



Mullaghmore . . . 



Buncrana 



Port Rush 



Carrowkeel 



Ballycastle 



Glenarm 



Donagliadee . . . 



Ardglass 



Cloglier Head . 



Kingstown 



Dunmore East . 



New Ross 



Passage West . . . 

 Castle Townsend 



Mean of large 



intervals from 



transit two days 



previous. 



m 



53 



6 



49 



8 19 

 7 3 



8 

 19 

 39 



27 

 4 



48 

 4 



7 

 7 

 7 

 8 

 9 

 9 

 10 



12 53 



13 10 

 13 14 

 13 21 

 13 26 



7 14 



8 5 



26 

 3 



Mean of small 



intervals from 



transit two days 



previous. 



55 



7 



54 



27 



3 



9 



23 



37 



21 



50 



8 44 



9 2 

 12 3 

 12 16 

 12 16 

 12 24 

 12 30 



16 



11 



31 



5 



Mean of all the 



intervals from 



transit two days 



previous. 



True 

 establishment in 

 Greenwich time. 



h 



6 



6 



7 



7 



6 



6 



6 



7 



7 



8 



9 



9 



12 28 

 12 43 

 12 45 

 12 52 

 12 58 



6 45 



7 38 

 6 58 

 6 34 



24 

 36 

 21 

 53 

 33 

 38 

 51 

 8 

 54 

 27 

 16 

 33 



43 

 55 

 40 



12 

 52 

 57 

 10 



27 



6 13 



6 46 



7 35 

 7 52 



10 47 



11 2 

 11 4 

 11 11 

 11 17 



5 4 



57 

 17 

 53 



p2 



