THE BAHAMA ISLANDS 95 



HEIGHT RELATIONS. 



Ft. 



Mean of all high waters on fixed tide staff 4.332 



" low " " " 1.698 



" " higher high waters on fixed tide staff 4.640 



" " lower low " " " 1.632 



" of the tropic higher high waters on fixed tide staff 4.728 



" " " lower " " " " 3.726 



14 higher low " " " 1.867 



4 " " lower ' 4 4l 4i " 1.587 



" Spring high water on fixed tide staff 4.54O 



low 4l 44 " 1.489 



" Neap high " 44 " 4.O79 



low " " " 1.950 



" Perigean high " " " ... . ? 4.61O 



" " low " " - 4 1.42O 



" Apogean high " " " 4.077 



low" " " 1.953 



" sea level from hourly heights of the sea, on fixed tide staff 2.991 



" half- tide level from high and low waters, " " 3.015 



RANGES, INEQUALITIES, ETC. 



Ft. 



Mean range of all tides 2.634 



" Springtides 3.051 



" Neap 44 . 2.129 



44 the great tropic tides 3.141 



14 44 small " 44 1.859 



14 tides from mean higher high to mean lower low waters 3.O08 



44 ' 4 Perigean tides 3.190 



44 Apogean 4l 2.124 



' 4 the tropic diurnal wave 1.O18 



44 tropic high water diurnal inequality 1.002 



44 " low " " 44 O.280 



44 age of the phase tides Id Oh 



44 4l 44 parallax tides Id 18h 



44 44 " diurnal 4l Od 3h 



ANNUAL VARIATION IN MEAN SEA LEVEL AT NASSAU. 



Date. Sea level Date. Sea level Date. Sea level Date Sea level 



feet. feet. feet. feet. 



Jan. 1 -.3 Apr. 1 -.1 July 1 +.1 Oct. 1 +.3 



44 16 -A " 16 -.1 " 16 +.2 " 16 +.2 



Feb. 1 -A May 1 Aug. 1 +.2 Nov. 1 +.1 



44 16 -.3 44 16 " 16 +.3 " 16 O 



Mar. 1 -.3 June 1 +.1 Sept. 1 +.3 Dec. 1 -.1 



' 16 -.2 " 16 +.1 " 16 +A 44 16 -.2 



The above table was computed from the formula 



x = Sa cos (h Sa} + Ssa cos (2h Ssa) 



where x := height of mean sea level, -j- when above, when below the mean 

 of entire year. 



Ji the mean longitude of the sun. 



The other symbols are the harmonic constants for the annual and semian- 

 nual inequalities. The values in the table do not exactly average zero, on ac- 

 count of fractions neglected in reducing to a single decimal place. 



