On the tides

Since the author presented his last paper on the tides to the Society, his attention has been directed to ascertain the three following points: namely, 1st, Whether, from the discussion of the Liverpool observations with reference to a previous transit, these observations present the same kind of agreement with Bernouilli’s theory as those of London: 2ndly, Whether, by taking into account a greater number of observations, the results given in his last paper remain sensibly unaltered: and 3rdly, Whether theestablishment of the Port of London varies sensibly in different years; and whether the removal of the old London bridge has occasioned any difference. In order to elucidate these points, he procured the assistance of Mr. Jones and Mr. Russell to compute numerous tables; employing for that purpose a further sum of money placed at his disposal with this view by the British Association for the Advancement of Science. The results contained in the tables here presented, are all laid down in diagrams, on the same plan as those contained in his last paper, by which means they are much more readily understood. The author finds that the semi-menstrual correction for the interval at Liverpool presents the same agreement with observation as had been before noticed; while the form or law of the semi-menstrual correction for the height is also the same as that indicated by the observations; but in order to render the agreement complete it would be necessary to change the epoch, or to make a slight movement of the theory-curve in the diagrams. This remarkable difference also obtains in the London semi-menstrual correction for the height. The calendar month inequality at Liverpool, considered as resulting implicitly from the corrections due to changes in the declinations of the luminaries, and in the sun’s parallax, agrees generally with Bernouilli’s theory, and with the results deduced from the London observations given in the author’s last paper.