^.- 



1. 



I 



i 



f 



L . 



L 

 L 



P 



J 



I 



^ . 



ra' 



i t 



J 



I 



fi 





^ 



./^p 



^1 T 



If 



Sect. IVO 



TIDES, 



1 



1 -^ 



13, To cornpare the times of higli water witli tlie times 



UjtvO 



) tlie 



of the moon's transit (see Art. 10), we must t 

 moon's transit from the tables (see Art. 1), and reckon 



ft 



moon's transit, and put down these intervals, which are 

 called the lurdtidal intervals* 



Suppose, for example, that we have the observatitms of 

 hi'^h water contained in the following t^ble : we add to 

 them the other columns, containing the moon's trc. it and 



the lunitidal interval calculated therefrom. TliC alteri 

 transits are interpolated midway between the others, which 



are given by the table. The a.m. 

 on the 14th is given in the table 



-n5 





12h. 32m. on the 



13th, the hour of the table being reckoned from Boon. 



1347. 

 Jan. 



i 



11 A.M. 



PM. 



12 A.M. 



Times 



of 

 H.W. 



h. m. 



Times of 

 Moon's 



Transit, 



Luni- 







1847, 



I Interval 



Vd 



14 



P.M. 

 A.M. 

 P.M. 

 A.M. 



1 

 I 

 1 



7 

 29 

 53 



P.M. 



15 A.M. 



P.M. 



2 11 

 2 29 



2 48 



3 3 

 3 21 



3 36 



h. 



[10 

 10 



[11 



11 



[0 

 



[0 



1 



33] 

 57 



21] 



45 



9] 

 32 



55] 



19 



h. m. 



Times 

 of 



Times of 

 Moon's 



Jan. I H.W. 



I ran sit. 





[I 42] 



i 2 



34 1 



1 



1 2 



32 



2 



26 



2 



20 



2 



16 



2 



8 



2 



2 



1 



52 I 



16 A.M. : 3 



54 



17 



18 



19 



P.M. 



A.M. 



P.M. 



A.M. 



P.M, ! 



A.M, 



4 9 



P.M. i *J 



4 



4 

 5 

 5 

 5 



20 



1 



48 



A.M. i 

 P.M. i 



6 



26 



43 



3 



23 



47 



9 



34 



2 



3 



[4 



4 



[4 

 5 



m. 

 6 



291 



52' 



15] 



39 



3] 

 27 

 51] 



In 



Luni- 

 tidal 

 In i er val 



h. m. 





40 





34 





28 





24 





20 





18 





18 





IS 





20 



■r^* 



14. To see whether the lunitidal intervals follow the 



* It is not necessary, for the purposes considered in these directions, 

 to calculate the time of the moon's transit at the place of observation by 

 differences of days. It is sufficient to take the time of the moon's transit 

 at Greenwich, and to add two minutes for every hour of tvest longitude 

 of the place. For the moon (on the average) moves away from the sun ^o 

 tluit her distance from the sun is increased 48 minutes in time for every 

 24 Itours, and therefore the transit of the moon is later at every other 

 place by two minutes for every hour. 



