876 REPOiiT— 1872. 



33. The agreements between the analyzed amplitudes and epochs for the 

 whole of the short-period tides are, on the whole, satisfactory. The chief 

 discordances occur between the evaluated quantities of the lunar elliptic 

 semidiurnal tides L, N, X, and v. It is extremely probable that a period ex- 

 tending through two entire years would give a much better agreement 

 between these quantities, the period being more nearly commensurable with 

 the majority of the chief tides, the period at present selected eliminating 

 only that of the mean lunar semidiurnal (M) tide. The values of the mean 

 sea-level show a general increase, although the value deduced for 1868-69 

 stands out prominently from those deduced for the preceding and following 

 years. This uncertainty will aifect sometimes, to a considerable amount, the 

 prediction of tide-heights from a Jixed datum, although such results arc 

 better and more intelligible than predictions reckoned from low water of 

 ordinary spring-tides. 



34. Through the kindness of Prof. J. E. Hilgard, of the United States 

 Coast Survey Office, three years' tidal observations, taken at Fort Point 

 (lat. 37°-67 N., long. 8"-15 W. of Greenwich), San Prancisco Bay, California, 

 were received and analyzed, with the following results : — 



Year ... 1858-59. 1859-60. 1860-61, 



ft. ft. ft. 



A(,=87io3 8-2651 8-i6o8 



I = 28°-o 26°-9 25°-4 



S. Speed of semidiui-nal 2(y—>j). M. Sjieed of semidiurnal 2(y— (7). 



' 1859-60. 1860-"61? 1858-59. 1859-60. 1860-6L 



very small, very small, o'o539 00808 o'o86j 



46°'3o i89°'37 32°7i 



0*3802 0-3824 1-6694 1-6215 1-6645 

 335°-8o 336°-45 330°-8i 33i°-3o 3i8"-72 

 very small. very small, very small. 



Ej very small, very small, very small, 0-0616 0-0712 o"c698 



«4 *3°'3^ 26^73 ii°-i5 



MS. Speed (4y-2(T-2»;). 



1858-59. 1859-60. 1860-61. 

 E4 0-0248 0-0325 0-0315 



e^ -2''"33 12°-25 22°-8l 



K. Speed of semidiurnal {2y). 



1858-59. 18,59-60. 1860-61. 



K, i'337o i"3036 1-2925 



ej i92°-i7 i9o°-88 i88°-55 



Ej o"i7S9 0-1716 o'i35i 



63 326°-65 3H°'53 3°^°'7S 



O. Speed (y-2(T). P. Speed (y -27;). 



18.58-59. 1859-60. 1860-61. 1858-59. 1859-60. 1860-61. 

 Ej 0-8917 0-8511 0-8784 0-3672 0-3659 0-3869 



6; 3°-39 6°-25 4°oi i^°-52 is°-90 n^'S^' 



