OF THE TIDES IN THE PORT OF LONDON. 



23 



And on applying this correction, the residual quantities are, with one or two excep- 

 tions, within the limits + 4"" and — 4™. 



4. The Correction for Lunar Declination. — In Table IX. of his Memoir, Mr. Lub- 

 bock has arranged the intervals of the time of tide and moon's transit according to 

 th.e declination of the moon, taken for every three degrees ; and in Table XIX. he has 

 given the difference of these intervals from the mean, arranged according to declina- 

 tion and time of transit. On inspecting this Table, it appears that this difference 

 from the mean, or correction for lunar declination, is, for all values of the time of 

 transit, when the declination has its mean value of about 16°, positive when the 

 declination is less, and negative when it is greater than this. The correction for a 

 given declination, as shown in the vertical columns, is not constant, but it appears 

 difficult to determine whether the variations are accidental or are the consequences of 

 the form of the correction. Till we have better data, I will neglect these variations. 



Taking, then, the sums of the vertical columns in Table XIX., we find as follows 

 (the sums being expressed in minutes) : 



Table showing the Difference in the Interval between the Time of the Moon's Transit 

 and the Time of High Water, and the Mean Interval (Column A. Table III.) for 

 every Three Degrees of the Moon's Declination. 



