56 The Rev. S. Haughtou on the Solar and Lunar 



Solar Diurnal Tide. 



4. Age of tide. 



5. 7s= solitidal interval. 



6. S= coefficient of solar tide. 



These constants were found as follows from the comparison of 

 the observed and calculated tides : — 



1, The age of lunar tide was found from the comparison of 

 the times of vanishing of the observed and calculated tides. 



2. The lunitidal interval = /,„ was found from the equation 



. Range of lunar diurnal tide at high water ,„. 



^ "^' "" Range of lunar diurnal tide at low water 

 4. The lunar coefficient = M was found from the equation 

 2M sin 2 (max. value of yu.) = 



/ (Range of lunar diurnal tide at high water)- /^«, 

 A/ + (Range of lunar diurnal tide at low water) ^ 



4. The age of solar tide was not determined. 



5. The solitidal interval =i was found from the comparison 

 of the solstitial intersections of the observed diurnal tide with 

 the calculated lunar tide. 



6. The coefficient of the solar tide = S was found from the 

 equation 



2Ssin 2(max. value of a) = maximum range of solar diumal 

 tide (5) 



Section III. Diurrud Tide at Castletotvnsend. 



Having constructed the observations contained in the calcu- 

 lated tables by means of curves, as already described, I found it 

 impossible to separate the effects of the sun and moon. The 

 tide is so small, and its times of vanishing consequently so badly 

 marked, that it was not possible to divide it with any kind of 

 certainty into a solar and lunar tide. I therefore supposed the 

 tide to be due to the moon only, and made the following infer- 

 ences, which I do not, however, consider as of high value. 



The mean of all the maximum values of the tide at high water 

 was found to be +0"0885 and — 0'0835, giving an average 

 range at high water of 0-1720 ft. 



The mean of all the maximum values at low water was found 

 to be +00820 and — 0'0906, giving an average range at low 

 water of 0-1 726 ft. 



If, therefore, h and / represent the ranges of diurnal tide at 

 high and low water respectively, we have, by equation (2), 



/i = 2M sin (2 max. declination) cos (?« — ?',„) 



/=2M sin (2 max. declination) cos (90° + ??i — ?„,) ; 



