19 



Report on the Discussions of Tides, prepared under the direc- 

 tion of the Rev. W. Whewell, F.R.S., by means of the grant 

 of money made for that purpose by the Association. 



The grant of money made at the last meeting of the Associa- 

 tion, has enabled me to continue the discussions of tide observa- 

 tions which I had already carried on for some time, and to ob- 

 tain some results which I hope will be considered as valuable. 

 I engaged Mr. Bunt to proceed with those discussions, accord- 

 ing to methods which I had previously framed, and instructed 

 him in the execution of j and at present, his skill in the appli- 

 cation of these methods being improved by practice, and stimu- 

 lated by a great zeal and love for the subject, I believe his work 

 (which I produce to the meeting,) will be found of extraordi- 

 nary accuracj' and clearness. I am fully persuaded that in con- 

 sequence of the advantage of the plan pursued, and of the ex- 

 cellent manner in which Mr. Bunt has executed it, the exact- 

 ness of the results is of a most unexpected kind : for example, 

 it is quite clear that the tables for semimenstrual inequality and 

 for lunar parallax, (if not for declination,) obtained by our me- 

 thods from a year's observations, are as good as those previously 

 obtained from the discussion of nineteen years' observations. 

 And the proof of this is found, not only in the regularity which 

 the curves expressing the corrections exhibit without any arbi- 

 trary impi'ovement whatever, but also in the complete symme- 

 try of the curves above and below the mean ; the parallax cor- 

 rection curves for 60' and for 54' (3' above and below the mean 

 570 '^^^ t)f exactly the same form. 



I have given an account of the results of these discussions in 

 a memoir read before the Royal Society, and printed in their 

 Transactions, entitled "On the Determination of the Laws of the 

 Tides from short series of Observations," being the ninth series 

 of my tide researches. An account is also there given of the 

 method pursued by Mr. Bunt in these discussions. I may men- 

 tion here the questions of which I have in that paper attempted 

 the solution. 



1 . To which transit of the moon ought we to refer the tide ? 



2. How does a change of the epoch affect the semimenstrual 

 inequalities ? 



•S. How does a change of the epoch affect the (lunar) parallax 

 correction of the times ? 



4. How does a change of the epoch affect the (lunar) declina- 

 tion correction of the times ? 



c 2 



