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 meau value 



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



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-monthly Inequality in Height. — The theoretical expression for the half 

 monthly inequality in height of high water is: 



n = ^ \h'- + h 1 + 2 h'h cos. 2<p\ l 

 where r t expresses the height of the pole 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: 



n = v/ \h' 2 + h 2 + 2h'h cos. 2 ($>— a) } 8 



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

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





1 See Phil. Trans. Royal Soc, 1834 and 1836. 



12 Encyclopaedia Metropolitana, Tides and Waves, Art. (535). The expression given by Mr. Lub- 

 bock is : 



h = D + (A') {(1 + «-) (A)i os. (24,-2*0 4- (1 + £)cos. 2 4 ! ; 

 i c c ) 



for wliicli sec his treatise 



