THE BAHAMA ISLANDS 93 



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



for 1894, becomes 



Mn = 2.04 M, X Table 22 + .035 M, (y — w) siu {'ZMl — M\) 



+ M.^ (cos V + cos w) + 2il/g cos (3 Ml — Ml) — 2M, (12) 



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 higli and low waters this range was found to l)e 



Mn — 2.634 ft. 

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

 constants by the formulas 



.96 —.08 



■)] 



1.96^.08f-^Lt^iV 



M, 

 X [^^2 + /h COS (2i/« ~Sl- /..«)] (13) 



X [S., + p., cos (2^« -SI- !4)\ (U) 



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. X Table 45, above iVSL (15) 



" LHW^ " '' " " (16) 



" HLW= '' " " " (17) 



" LLW= " " " " (18) 



where A. = 1.010 M, + 0.27 ^j, — K, cos [(^? — 6»;) ^ (Al - Ml)l 



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. 

 Z^l^= 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 



