The Rev, Brice Bronwin 07i the Theory of the Tides. 187 



base is about equal to that of the acids. There is especially 

 a much less quantity of phosphoric acid to a larger amount 

 of peroxide of iron in the blood, than in the seeds of the Le- 

 guminosa^BY the Cerealia. At all events, the blood is a me- 

 roxidic substance; and the teleoxidic portion of it is only 

 apparently greater than the anoxidic, because the large quan- 

 tity of alkaline chlorides in the former cannot be considered 

 as forming part of the teleoxidic portion. 



[To be continued.] 



XXV. On the Theory of the Tides. 

 By the Rev. Brice Bronwin*. 



TPHE true principles of fluid motion were not known when 

 -*- Bernouilli and Euler produced their Theories of the 

 Tides; and though Laplace in his Theory set out with the 

 proper equations, he did not succeed in integrating them. 

 After a very elaborate discussion of the subject, and arguing 

 in a retardation, he concluded by merely making the height 

 of the tide proportional to the disturbing forces of the sun and 

 moon. There are two grand defects in all these theories. 

 There is no retardation of the water resulting from the mathe- 

 matical theory itself. If we set aside the contrivances to ac- 

 count for, or argue in a retardation, they give high water 

 immediately under the luminary that raises it. And also they 

 in reality make the direct action of the sun and moon to pro- 

 duce the whole of the effect; whereas it is admitted that in 

 narrow seas at least their direct action produces no sensible 

 effect, which indeed is evident from very obvious considera- 

 tions. 



It is upon the horizontal displacements of the water that 

 the height of the tide and the retardation chiefly depend. But 

 these have been neglected ; in fact all the difficulty lies here. 

 Laplace did not succeed in integrating his equations. The 

 thing wanted is, to make 8/j, the variation of the pressure, a 

 complete variation. Until this be done, we cannot expect to 

 possess a theory which shall harmonize with the phsenomena. 

 What, therefore, I propose in this and one or two more papers 

 is, not to give a complete theory of the tides, the phaenomena 

 of which are in a great measure out of my way, but to attempt 

 to make Ip a complete variation. 



Laplace's theory is contained in the first and fourth books 

 of the Mecanique Celeste, from which I shall take the neces- 



* Communicated by the Author. 



