36 The Rev. Samuel Haughton on the Solar and Lunar 



These two classes of observations were made for the purpose of throwing 

 light upon different questions connected with the laws of the tides, the first 

 class of observations being intended to furnish data for the separation of the 

 effects of the Sun and Moon in the Diurnal Tide, — a problem not yet solved by 

 observation ; the second class of observations being intended to illustrate the 

 laws of the Semidiurnal Tide, particularly in the Irish Channel, and to decide the 

 true mean height of the water round the coasts of Ireland. 



As the two subjects are quite distinct, I have determined to present the re- 

 sults of my discussion of the tidal observations in separate communications to 

 the Academy. 



In the present communication I shall give the results of the calculations 

 made from the daily observations, with a view to determine the separate effects 

 of the Sun and Moon upon the Diurnal Tide. 



Section I. — Description of the Tidal Stations, and of the Tide-Gauge used in the 



Observations. 



I. Castletownsend, county of Cork. Lat. 51° 31' N. ; Long. 9° 7' W. — 

 The zero of the tide-gauge was carefully referred to the iron bolt driven verti- 

 cally into the rock in which the Coast-guard signal-staff is secured. 



The zero was 31 '91 feet below this bolt. The gauge at this station was 

 placed in the open sea, and was held in its place by stays and guys made fast 

 to the rock. 



II. Cahieciveen, county of Kerry. Lat. 51° 57' N. ; Long. 10° 8' W.— 

 The zero of the tide-gauge, which was erected in the north-east angle above the 

 bridge, was referred to a provisional bench-mark made on the corner coping- 

 stone of the bridge. 



The zero was 23'51 feet below this mark. 



IIL KiLRusH, county of Clare. Lat. 52' 38' N. ; Long. 9° 26' W.— The 

 tide-gauge was placed at this station on the sea face of the steam-boat pier, and 

 consequently exposed to the gales from the south-west. This was the only posi- 

 tion in which it could be placed, and, unfortunately, it was twice washed away 

 by the violence of the waves. 



The zero was referred to the copper bolt driven vertically into one of the 

 facing stones of the pier, and was found to be 20-59 feet below this bolt. 



