377 



logous appearances of incommunicable colours presented by mother- 

 of-pearl, which had hitherto baffled all previous attempts to explain 

 them ; but which now appear to be produced by occasional intermis- 

 sions in the processs by which the material of the shell is secreted 

 and deposited in the progress of its formation. 



March 3, 1336. 



The Rev. WILLIAM WHEWELL, M.A., Vice-President, in the 



Chair. 



The Right Hon. the Earl of Minto and Joshua Field, Esq., were 

 elected Fellows of the Society. 



A paper was read, entitled, " Researches on the Tides. Fifth 

 Series: On the Solar Inequality, and on the Diurnal Inequality of 

 the Tides at Liverpool. 1 ' By the Rev. William Whewell, F.R.S., 

 Fellow of Trinity College, Cambridge. 



The inequality both in the height and time of high water in the 

 morning and evening tides of the same day, which varies according 

 to a law depending on the time of the year, is termed by the author 

 the diurnal inequality, because its cycle is one day. The existence of 

 such an inequality has often been noticed by seamen and other ob- 

 servers j but its reality has only recently been confirmed by regular 

 and measured observations ; and its laws have never as yet been cor- 

 rectly laid down. The author gives an account of the observations 

 now in progress at different ports, from which he expects they will be 

 ascertained with great precision. He traces the correspondence of 

 the observations of the diurnal inequality already made with the equi- 

 librium theory ; and remarks that the semi-diurnal tides, alternately 

 greater and less, which are transmitted from the Southern Ocean to 

 Liverpool, may be compared to the oscillations of a fluid mass : and 

 that they are augmented by the action of the forces occurring at in- 

 tervals equal to those of the oscillations. Hence the oscillations go 

 on increasing for a considerable period after the forces have gone on 

 diminishing, and reach their maximum a week after the forces have 

 passed theirs. 



The remaining sections of this paper are devoted to the investiga- 

 tion of the Solar inequalities at Liverpool. By carefully eliminating 

 the Lunar effects, which the author is enabled to do by the aid of the 

 preceding researches, he has determined the approximate circum- 

 stances of the Solar correction for the height. He has also obtained 

 evidence of the existence, and some knowledge of the laws of the 

 Solar inequalities of the times ; and these inequalities, as thus dis- 

 covered, are found to exhibit the same general agreement with the 

 equilibrium theory which has been disclosed in all the inequalities 

 hitherto detected. The results of the extensive observations now ob- 

 tained are sufficiently precise to indicate the defects of our mathema- 

 tical theories of hydrodynamics; and some of these are pointed out 

 by the author, who remarks that although a short time ago the theory 



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