154 



HE CORD AND RESULTS OF 







uequality in higl 



1 water. 



Inequality in low water. 



C 's tran. 



P=55' 



57' 



59' 



P=55' 



57' 



59' 



P=55i' 



57' 



582' 



P=55|' 



57' 



58|' 



0" 30™ 



+ 4- 



+ 3" 



+ 8- 



+ V\2 



+ 1M 



+ 1M 



+ 3- 



+ 5" 



+ 7- 



— ift.o 



— 1".0 



— 0«.9 



1 30 



—16 



—15 



— 6 



+ 1.3 



+ 0.8 



+ 0.4 



—24 



—17 



—11 



—0.8 



—0.9 



—0.7 



2 30 



—32 



—34 



—27 



—0.1 



+ 1.0 



+ 1.3 



—41 



—30 



—19 



—1.0 



—0.9 



—0.5 



3 30 



—43 



—39 



—29 



+ 1.0 



+ 0.7 



+ 0.3 



—33 



—34 



—32 



—0.5 



—0.3 



0.0 



4 30 



—41 



—46 



—49 



—0.5 



—0.3 



—0.1 



—40 



—49 



—41 



+ 0.6 



+ 0.5 



+ 0.1 



5 30 



—24 



—24 



—21 



—0.7 



—0.9 



—0.8 



—32 



—27 



—21 



+ 0.7 



+ 0.8 



+ 0.9 



6 30 



—25 



— 5 



—13 



—1.2 



—1.2 



—1.1 



—11 



—10 



—13 



+ 1.4 



+ 1.5 



+ 1.4 



1 30 



+ 35 



+ 31 



+ 23 



—1.4 



—1.3 



—0.7 



+ 28 



+ 24 



+ 11 



+ 1.6 



+ 1.4 



+ 0.8 



8 30 



+ 39 



+ 35 



+ 33 



—0.7 



—0.7 



—0.5 



+ 61 



+ 51 



+ 41 



+ 0.9 



+ 0.3 



—0.1 



9 30 



+ 49 



+40 



+ 33 



—0.1 



—0.2 



—0.1 



+ 46 



+ 33 



+ 11 



—0.1 



0.0 



+ 0.2 



10 30 



+ 31 



+33 



+ 23 



+ 0.6 



+ 0.3 



+ 0.1 



+ 33 



+ 32 



+ 27 



—0.3 



—0.2 



—0.2 



11 30 



+ 15 



+ 19 



+ 29 



+ 0.8 



+ 0.7 



+ 0.6 



+ 11 



+ 22 



+ 40 



—1.1 



—0.9 



—0.7 



Range, 



87 



84 



76 



2.7 



2.5 



2.1 



90 



84 



76 



2.7 



2.6 



2.3 



The ranges of the mequaHty for time and height were taken from a graphical 

 process to free them from the incidental irregularities of the tabular numbers. 



As the parallax increases the range of the inequality in time for high and for low 

 water decreases at the rate of nearly 3™ for high water, and of nearly 4" for low 

 water, for each minute of change of parallax. 



With respect to the inequality range in height an increase of parallax is followed 

 by a decrease in the range for high and low water ; this latter result, hqwever, I do 

 not think as fuUy established. 



The parallactic results for Liverpool and London (Phil. Trans. 1836) accord, 

 upon the whole, quite well with those given above for Port Foulke ; only residts for 

 high water^ are given. 



The variations in the retard of the tide depending on variations of parallax were 

 mad« out by means of a graphical process ; it appears that for increasing parallax 

 the angle a increases for high and low water at a rate of about 3" for each minute 

 of parallactic change. This accords also weU with the Liverpool residt. 



Effect of Clianges of the Ifoon's Declination on the Half-montlily Inequality. — The 

 effect of the declination changes may be found by the use of the same method as 

 that employed in the parallactic investigation, but as the declination effect varies as 

 the square of the declination, the greater the number of groups, arranged for decli- 

 nations between 0° and ±26°, the more reliable will be the result. Our short series 

 will not permit the formation of even two full groups, the first comprising declina- 

 tions between 0° and +16°, the second between +16° and +26°. The moon's 

 declination preceding the effect by one day has been employed. It was found 

 necessary to contract the tabulation of the half-monthly inequality from 12 to 6 

 values; for transits near l*" and ll"" only high declinations occur; for transits near 

 7'' only low ones ; no results could therefore be inserted for these hours. D stands 

 for declination. 



* Par less attention has hitherto been given to the laws of low water than to those of high water ; 

 the latter are practically of greater importance, but theoretically there is no difference in their value. 



