256 



and from these springs is derived from atmospheric air, held in solu- 

 tion by the water, and deprived of the. greater part of its oxygen by 

 animal and vegetable putrefaction. He is disposed to ascribe the de- 

 ficiency of oxygen to some process of combustion, during which it 

 unites with some base, forming a compound not easily volatilized by 

 heat; and to account for the presence of carbonic acid, by the calci- 

 nation of earthy carbonates, rather than by the combustion of coal or 

 bitumen. 



The Society then adjourned over the Christmas Vacation, to meet 

 again on the 9th of January. 



January 9, 1834. 



BENJAMIN COLLINS BRODIE,Esq.,Vice-President,in the Chair. 

 The Earl of Tyrconnel was elected a Fellow of the Society. 



A paper was read, entitled, "On the empirical Laws of the Tides 

 in the Port of London, with some Reflections on the Theory." Bv 

 the Rev. William Whewell, M.A., F.R.S., Fellow and Tutor of Trinity 

 College, Cambridge. 



The present state of our knowledge of the tides is represented bv 

 the author as extremely imperfect, and at variance with the scientific 

 character which Physical Astronomy is supposed to have attained ; 

 for although it be the universally received opinion that they are the 

 direct results of the law of gravitation, the exact laws by which the 

 phenomena are actually regulated with regard to time and place 

 have never been strictly deduced from this general principle. The 

 tide tables that have been given to the world are calculated by em- 

 pirical methods, which are frequently kept secret by those who employ 

 them ; and the mathematical solutions of the problem hitherto at- 

 tempted have been confessedly founded on hypotheses which are in 

 reality very remote from the real facts j and accordingly it is doubtful 

 whether they give even an approximation to the true result. The 

 comparison of the results of theory with extensive series of observa- 

 tions had not been attempted previously to Mr. Lubbock's discussion 

 of the tides of the port of London, recorded in the Philosophical 

 Transactions for 1831. The establishment, on theoretical grounds, 

 of rules for the calculation of tide tables, has been attempted by Ber- 

 noulli and by Laplace : the methods recommended by the former are 

 probably the foundation of those at present used by the calculators 

 of such tables, that of Laplace being complicated, and too laborious 

 for practice. Original tide tables are very few j none, with which 

 the author is acquainted, deserving that tide, except those which are 

 published for Liverpool, and those for London. The former, which 

 are calculated according to rules obtained from Mr. Holden, from the 

 examination of five years of observations, made at the Liverpool docks 

 by Mr. Hutchinson, at that time harbour-master, are remarkably 



