li.s 



RECORD AND REDUCTION OF THE TIDES. 



The mean establishment resulting from the observed times of 4S0 high waters 

 at Van llensselaer Harbor is therefore ll 1 ' 43.3'", referred to the moon's transit 

 immediately preceding and corresponding to a mean horizontal parallax of the 

 moon and sun, and to the moon's and sun's declination of 16° nearly. The mean 

 interval corresponds to the moon's transit of h 21 m nearly, indicating that the 

 epoch would have come out b m if transit E (see An Elementary Treatise on the 

 Tides, by J. W. Lubback, Esq., London, 1839) or that immediately preceding 

 transit F had been used. 



In like manner we obtain the following table from the observed times of 485 

 low waters at Van Rensselaer Harbor : — 



The mean establishment resulting from the observed times of 485 low waters is 

 17 h 48.0"', referred to the moon's transit immediately preceding low water, and the 

 same to which the preceding high water has been referred ; the difference between 

 the two mean intervals is 6'' 04.7 m . 



To obtain a numerical expression for the half-monthly inequality in time, the 

 value for a should be determined so as to furnish, in particular, good results for 



