TIDAL OBSERVATIONS. 



139 



g 



eries I. 1860. 





S 



Bries II. 1861 







Half-tide. 



([_ 'a declination. 





Half-tide. 



C 's declination. 



November 11 



.... 



— 21°.0 



June 6 



15". 70 



+ 22°.8 



18 



11". 82 



— 17.2 



7 



15.78 



+ 24.5 



19 





—12.6 



8 



16.06 



+ 25.2 



20 



.... 



— 7.7 



9 



16.18 



+ 24.5 



21 



11.21 



— 2.6 



" 10 



16.35 



+ 22.6 



" 22 



11.50 



+ 2.5 



" 11 



16.31 



+ 19.5 



23 



11.56 



+ 7.6 



" 12 



16.09 



+ 15.3 



24 







+ 12.4 



" 13 



16.24 



+ 10.3- 



25 







-fl6.9 



" 14 



16.17 



+ 4.7 



26 



11.28 



+ 20.7 



" 15 



16.20 



— 1.1 



2t 



11.70 



+ 23.6 



" 16 







— 7.0 



28 



11.56 



+ 25.4 



u lY 







—12.6 



29 



12:97 



+ 25.9 



" 18 



16.49 



—17.6 



30 



14.20 



+ 25.0 



" 19 



16.54 



—21.6 



December 1 



13.84 



+ 22.6 



" 20 



16.34 



—24.2 



2 



13.52 



+ 19.0 



21 



15.76 



—25.2 



3 



13.25 



+ 14.4 



" 22 



15.71 



—24.4 



4 



18.81 



+ 8.9 



" 23 



15.70 



—22.2 



5 



14.22 



+ 3.0 



" 24 



15.80 



—18.7 



" 6 



14.09 



— 3.2 



" 25 



15.97 



—14.3 



1 



14.00 



— 9.3 



" 26 



16.02 



— 9.4 



" 8 



14.04 



—14.9 



" 27 



16.06 



— 4.2 



9 



13.47 



—19.7 



" 28 



16.15 



+ 0.9 



10 



13.92 



—23.3 



29 



16.93 



+ 6.1 



11 







—25.4 



" 30 



17.17 



+ 10.8 



12 



16.47 



—25.9 



July 1 



17.17 



+ 15.2 



13 



16.47 



—24.7 



" 2 



17.17 



+ 19.0 



14 



16.73 



22.2 



3 



17.11 



+ 22.0 



15 



16.59 



—18.6 



4 



16.77 



+ 24.2 



16 



16.70 



—14.2 



5 



16.82 



+ 25.1 



n 







— 9.3 



6 



18.05 



+ 24.9 



18 



16.40 



— 4.2 



7 



18.06 



+ 23.3 



19 



16.45 



+ 0.9 



8 



17.92 



+ 20.4 



20 



16.33 



+ 6.1 



9 



17.60 



+ 16 4 



21 



16.14 



+ 11.0 



" 10 



17.89 



+ 11.6 



22 



16.04 



+ 1.5.5 



11 



17.61 



+ 6.0 



23 



16.19 



+ 19.5 



12 



.... 



+ 0.2 



An examination of the figures makes it evident that the zero shifted between 

 November 28th and 30th, from some unexplained cause, hj about 2.4 feet, and 

 again on the 4th and 10th of December by 0.7 and 2.5 feet respectively, on which 

 dates the tide rope had been taken up and replaced. These displacements are all 

 in the same direction, indicating deeper water. In the second series there are 

 breaks between June 20th and 21st, between June 28th and 29th, and on July 6th, 

 of — 0.7, +0-9? ^iid -f 1.2 foot respectively, all in consequence of a derangement 

 of the apparatus as stated in the record. The breaking down of the apparatus on 

 June 17th does not appear to have affected the mean level reading. 



Yariation in tlie Mean Level of the Sea. — In accordance with the equilibrium and 

 wave theories (533) of " Tides and Waves," by G. B. Airy, Astronomer Royal, 



