THE BAHAMA ISLANDS 93 



which, by means of Table 22, Appendix 7, Coast and Geodetic Survey Report 

 for 1894, becomes 



Mn = 2.04 M, X Table 22 + .035 M, (v w} sin (*M\ M\] 



+ M, (cos v + cos w) + 2 M 6 cos (3 Ml Ml} ZM z (1 2) 



in which the v and w are the same as obtained for (1) and (2). By (12) the 

 mean range of tide at Nassau from the harmonic constants is 



Mn = 2.609 ft. 

 and from the high and low waters this range was found to be 



Mn = 2.634 ft. 



The spring and neap ranges of tide may be obtained from the harmonic 

 constants by the formulas 



8g = Mn - .536 JL + [l.96 - .08 



X [S 2 + ^ cos (2Jf 8$ /)] (13) 





N P = * -.686-.- [1.96 -. 



08 



X [ff, + ^ cos (21f8 - SI - /^)J (14) 



in which the first and last letters of the words spring and neap are used as 

 abbreviations. 



From (13) and (14) we obtain 



Sg = 3.051 ft., and Np = 2.129 ft. 

 The heights of the tropic tides may be found by the following formulas : 



Tropic HHW = 1.02 A 2 X Table 45, above MSL (15) 



" LHW= " " " " (16) 



" HLW= " i( " " (17) 



" LLW= " " " " (18) 



where A 2 = 1.010 M, + 0.27--^ cos [("? 6>?) ~ (K\ M$], 



and the table is in Appendix 9 of the Coast and Geodetic Survey Report for 

 1897, different arguments being used for entering the" table for the various 

 tides. From (15), (16), (17), and (18), we find 



Tropic HHW 1.737 ft. above mean sea level. 



LHW = 0.735 " " " " " 

 " HLW= 1.124 " below " " " 

 " LLW= 1.404 " " " " " 



The difference between the two high waters of the tropic tides is called the 

 tropic high water diurnal inequality, abbreviated to Tropic HWQ, and the 



