116 



The Rev. S. Hauahton on the Solar and Lunar 



or, converting the arc into time, 



TO — i,„ = 2'» 4"^; 

 but since m is the moon's hour-angle, in Portrush time, at high 

 water, and is equal to 5** 47*", we have, finally, 



By equation (4), we have 



max. value of 2M sin 2fj,= ^ (0-59)2 + (0-34)2z= 0-681 ft. j 

 from which we obtain 



M = 0-519 ft. 



Also, since the maximum value of the solar tide is 0-35 feet, we 

 have 



max. value of 2S sin 2o-= 0-500 ft,, 

 and 



S = 0-342 ft. 

 Combining these results, we have for tide constants at Port- 

 rush, — 



1. Lunitidal interval =3^43°', 



2. Solitidal interval =llii30'». 



3. Age of lunar tide 



at high water =-5^ 9^. 

 at low water =4<i 19\ 



4. Lunar coefficient =0-519 ft. 



5. Solar coefficient =0-342 ft. 



6. Ratio of solar to lunar coefficient, 



or ^ = 0-659. 



The theoretical tides were constructed with the foregoing con- 

 stants, and compared with the observed tides. The results of the 

 comparison are given in the six following Tables: — 



Portrush Tide, Table A. 



Positive heights at high water for fifteen lunations, commencing 

 1850,November7d7J»45"^,andendingl851,December22d5'i35"». 



