ON THE COASTS OF IRELAND. 



123 



a considerable time. The obsei'vations at Dunmore East, as appears from the begin- 

 ning of the Table in page 88, were also continued without interruption for several 

 days. These circumstances appeared to me to offer a convenient opportunity of exa- 

 mining whether the tide occurring three times in the lunar day, which is pointed out 

 by theory, is sensible in the seas around Ireland. 



The calculations for this purpose were made in the same manner as the other cal- 

 culations described in Section X. The means for the twelfth parts of semidiurnal 

 tide, or for the twenty-fourth parts of diurnal tide, having been already found for the 

 operations in Section X., the means of the first and second, of the third and fourth, 

 of the fifth and sixth, &c. were taken ; and these were evidently the same as the means 

 for the twelfth parts of diurnal tide. They were then treated by the use of the 

 printed skeleton form shown in Section X., in the same manner as the means for the 

 twelfth parts of semidiurnal tide. Thus the diurnal tide and tertio-diurnal tide were 

 obtained; and a consideration of the principles on which that process is founded will 

 show that the result is in no way affected by the semidiurnal or quarto-diurnal tide. 

 The constants additive to the phase, at Courtown, were corrected where necessary to 

 adapt them to the supposition that the phases are measured from the mean water 

 preceding High Water, First Division, at Ardglass ; those at Dunmore East are re- 

 ferred to the same state of tide at Dunmore East. The angle jo in the following Table 

 increases by 360° in a tidal day. The day which is set down is that whose astrono- 

 mical commencement occurs in the tidal day (the limits of the tidal day will be seen 

 in Section X.). 



Courtown. 



Dav. 



Diurnal tide. 



June 29. 



30. 

 July 1. 



17. 



18. 

 19.' 



20. 



26.' 

 27.' 

 28.' 

 29.' 

 30J 

 31. 

 2.' 

 3. 

 4J 



I2J 

 13. 

 14. 

 15.i 

 16J 



Aug. 



ft. 



0-57 



0-31 



0-43 



0-20 



0-05 



0-24 



0-36 



0-38 



0-43 



0-49 



0-29 



0-25 



6-15 



0-16 



0-10 



0-38 



0-53 



0-34 



0-11 



0-09 



0-05 



0-26 



.sin (jo + 250 



• sin (jo + 253 

 . sin (p+ 264 

 . sin(jo+350 

 . sin(/)+201 

 . sin (p+ 265 

 . sin (p+ 261 



• sin (p+ 256 

 .sin (p+253 

 . sin(j(?+240 

 .sin (p+248 

 . sin (p+ 276 

 . sin(p+287 

 . sin(p+ 10 

 . sin (p-t 105 

 . sin (p+ 1(J6 

 .sin(p+ 87 

 .s'm(p+ 57 

 .s'm(p+357 

 , sin (p+ 46 

 .sin(p+286 

 . sin(/)+286 



Tertio-diurnal tide. 



ft. 



0-08 



0-04 



0-02 



0-14 



0-06 



0-05 



0-23 



0-06 



0-05 



0-06, 



0-08, 



0-08. 



0-10, 



0-01 , 



0-08. 



0-02, 



0-11 , 



0-12, 



0-07. 



0-11 . 



0-07. 



0-04. 



sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 

 sin 



(Sp+lSS) 

 (Sp+ 86) 

 (3/>+l77) 

 (3JO + 207) 

 (3/> + 236) 

 (3/?+ 279) 

 (3/? + 187) 

 (3/J + 179) 

 (3;? + 132) 

 (3/>+158) 

 (3p+ 84) 

 (3p+ 87) 

 (3p+ 98) 

 (3^0 + 306) 

 (3/? + 315) 

 (3p+ 3) 

 (3;) + 328) 

 (3/7 + 346) 

 (3/? + 238) 

 (3;> + 211) 

 (3yo + 264) 

 (3p+ 70) 



Dunmore East. 



Day. 



June 



July 



24. 

 25. 



26. 

 27. 

 28. 

 29. 



1. 



2. 



Diurnal tide. 



Tertio-diurnal tide. 



ft. 



0-33 



0-35 



0-20 



0-27 



0-33 



0-32 



0-19 



0-17 



n (jo + 208) 

 n(p + 207) 

 n(p+192) 

 n(jO + l70) 

 n(p+\6l) 

 n(p+150) 

 n(/> + 187) 

 n(;9 + l78) 



ft- 



0-16. sin (3/7 + 253) 



0-08. sin (3/7 + 304) 



0-11 .sin (3/7 + 220) 



0-10. sin (3/7 + 210) 



0-09. sin (3/7+ 182) 



0-00 



0-07. sin (3/) + 349) 



0-03 . sin (3/7 + 99) 



r2 



