314 Prof. G. H. Darwin. [June 10, 



in my example, because it is useless to attempt the evaluation of 

 these tides of long period from three months of observation. 



H.W. 



55 i 



23 



47 



19 



41 



19 



37 



26 



35 



37 



37 



52 



42 



66 i 



50 ii 



80 



57 



91 



63 

 None 



99 



67 

 101 



66 



99 



65 



92 



58 ii 



Sliii 



&c., &c. 



The sum of all the H.W. entries to the end of xiii is 9791. The 

 sum of all the L.W. entries to the end of xiii is 8577. There are 173 

 H.W. and 173 L.W. Hence mean sea-level is -^ (97918577), 

 which is equal to +3'51. It would have been better, therefore, to 

 have subtracted 103 inches instead of 99 inches from all the heights. 

 This would have given mean sea level at 0'49 from the datum 

 adopted. 



(d.) Sorting the Heights according to the Values of the Angles. 



In the tables below the column belongs to all angles between 

 and 5 ; 5 belongs to 5 to 10 ; and so on. 



