18 



MR. AIRY ON THE LAWS OF THE TIDES 



The numbers inclosed in brackets are supplied by conjecture, where the irregula- 

 rity of the tides made it difficult to discover with accuracy the times of evanescence. 

 A small error in these will produce very little error in the result for maximum coeffi- 

 cient. The numbers at Castle Townsend (where the diurnal tide is very small) are 

 the means between those for the adjacent stations, Passage West and Kilbaha. Cour- 

 town is omitted, as the peculiarity of the tides there made it impossible to take diurnal 

 tides at high water and low water in the same manner as for the other stations. 



The times when the moon's declination vanished are June 28'^-89, July 12*'-14, 

 July 26*^'18, and August 8*^50. In stating these, however, I must warn the reader 

 that these are not the only elements on which the time of evanescence of diurnal tide 

 depends, as will appear in the next section. 



Attempts were made to determine, in the same manner, the times of evanescence 

 of diurnal tide in time. The irregularities were however so great that in most cases 

 it was useless to attempt to assign the day : in the following instances only did the 

 results appear at all trustworthy. 



Times of Evanescence of Diurnal Tide in Time. 



It will be remembered that the time of evanescence of diurnal tide in time at low 

 water ought to coincide with that for height at high water, and vice versd. The 

 comparison of this table with that for height is not very satisfactory. 



The maximum values of diurnal tide were deduced in all cases by the process ex- 

 plained a short time since, adopting for the times of evanescence the days given in 

 the first table (or that from heights), and using the high water evanescence in height 

 with the low water diurnal tide in time, and vice versd. The following are the re- 

 sults : — 



