70 



RECORD AND REDUCTION OF THE TIDES. 



In the above diagram, the observed values are indicated by dots ; the computed 

 values are represented by curves. From the times we have seen the mean value 



^ (or ^ of the wave theory and (A) of Lubbock's) = 0.471, and a = 0*^ 36" ; hence, 

 h' \ 31" J \ ^ 



the age of the tide, or the time requisite for the moon to increase its right ascen- 

 sion by that amount, becomes ff days, or 18 hours. 



Half-mottfhij/ Inequalify in Height. — The theoretical expression for the half 

 monthly inequality in height of high water is: 



,7 = ^/ J/t'2 + A^ + 2 h'hcos. 2 cp\' 



where y; expresses the height of the \)o\e of the equilibrium spheroid above the 

 mean level of the surface ; for its application, and according to the wave theory, it 

 must be changed to: 



,7 = v/ \h'' + h"+ 2h'h COS. 2 (^— a) p 

 The foUowingi table contains the results of the observations from the high and 

 low waters, and the moon's superior and inferior transit: 



' Sue I'liil. Trans. Ruyul Soc, 1«.'J4 tuid 1830. 



» EncyclopiEtlia Metropolitaiia, Tides and Waves, Art. (535). The expression given by Mr. Lub- 

 bock is : 



l,==r>+ (E) .[ (] _,. 1) (A)ro..: (24 — 2t) + (1 + 5-')fo.«. 24]- ; 

 '■ c ) 



for wliiuii see liis treatiw. 



