TIDAL OBSERVATIONS. 



141 



70. Tho following is a comparison for twenty-nine days, commencing 18G8, 

 November 1, of the recorded heights as registered by the Manora self-regis- 

 tering tide-gauge, with the heights calculated from the tide-components de- 

 termined from the analysis of the first year's observations (§ 67). In the 

 calculation of the heights the mean level of the water as determined by the 

 observations of the whole year was used. The difference between this mean 

 level and the mean of the twenty-four houi-ly heights (corrected for all sen- 

 sible lunar influence) for each day is also given. The effect of this is to 

 greatly improve the differences (C — R). The following tide-components were 

 omitted in the calculations : — the whole of the long-period tides, and the 

 Helmholtz shallow- water quarter-diurnal tide MS ; likewdse the solar semi- 

 diurnal elliptic (R and T) and the lunar diurnal elliptic tides (J and Q), tlie 

 values of which have been obtained since the heights were computed. The 

 computations are for load time. 



1868, November 1. 



1868, November 2. 



