122 The Rev. S. Haughton on the Solar and Lunar 



From the preceding Tables, it is evident that the utmost 

 rehauce may be placed in the values of the tide constants at this 

 station. 



Section IX. Diurnal Tide at Donaghadee. 



From the Diurnal Tables, the solar and lunar diurnal tides at 

 Donaghadee were calculated separately, and found to give the 

 following I'esults : — 



I. Diurnal tide at high water. 



1. Maximum value of lunar tide for positive heights = 0'42 ft. 



2. Maximum value of lunar tide for negative heights = 0'38 ft. 



3. Maximum value of solar tide =0*28 ft. 



4. Diurnal solitidal interval r^'W^ \2^. 



5. Age of lunar tide =6'^ S**. 



II. Diurnal tide at low water. 



1. Maximum value of lunar tide for positive heights = 0*39 ft. 



2. Maximum value of lunar tide for negative heighls=0-42 ft. 



3. Maximum value of solar tide =0'28 ft. 



4. Diurnal solitidal interval =11*» 12"". 



5. Age of lunar tide =5'^ 2^. 



Adding the first two of each of the preceding, we obtain, — 



Range of lunar tide at high water =0*80 ft. 

 Range of lunar tide at low water =0'81 ft. 



Hence by equation (3), 



cot (m-i,„)= ^ = cot (45° 21') ; 

 or, converting the arc into time, 



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

 high water, and is 10^ 40"*, we obtain, finally, 



?„ = 7i'33«'. 



By equation (4), we have 



max. value of 2M sin 2/i= \/ (0-80)2+ (0-81)2 = ^.139 f^ . 



from which we obtain 



M= 0-868 ft. 



Also, since the maximum value of the solar tide is 0*28 ft., we 

 have, by equation 5, 



max. value of 2S sin 2cr=0-56 ft., 

 and 



S = 0-383 ft. 



