242 Scientific Proceedings, Royal Dublin Society. 



My object in the present Paper is twofold, being firstly, to set 

 forward, as plainly as possible the conflict of authority that exists 

 on the action of sea waves, with a view to induce competent observ- 

 ers to investigate a subject which is of such importance to both 

 engineers and geologists ; and, secondly, to attempt, by means of 

 my own experiments and observations, to reconcile certain facts 

 recorded by observers of unquestioned veracity, which facts seem 

 at first sight to be quite irreconcileable, and have indeed been 

 regarded as such. 



Nor can non-mathematical observers of wave-action place im- 

 plicit reliance on the results obtained by those who have studied 

 the subject from a theoretical point of view, as here also some of 

 the authorities of greatest repute fail to agree. 



The Eeports of Mr. Scott-Russell, published under the auspices 

 of the British Association, and " A Treatise on Tides and Waves," 

 by Sir Greorge Airy, in the Encyclopcedia Metropolitana, are authori- 

 ties much relied on at the present time. Referring to the former, 

 Mr. Kinahan remarks : — 



" It might have been supposed that the exhaustive report on 

 Waves by J. Scott-Eussell, F. R. S., &o., should have decided the 

 relative merits of the tidal currents and wind- waves in regard to 

 their drifting powers" {Proc. R. I. Acad., s.s. vol. ii., p. 443) ; whilst 

 Lord Rayleigh has referred to the latter work as " still probably 

 the best authority on the subject" ("On Waves," Phil. Mag., 

 s. 5, vol. i., 1876, p. 262). 



Unfortunately the writers of these authoritative works were 

 not agreed as to certain important points. Sir Greorge Airy 

 warned his readers against a too ready acceptance of Mr. Russell's 

 first Report on Waves, in the following terms : — " We shall repeat 

 our opinion of the great value of the experiments which we have 

 abstracted, but we must warn the reader against attaching any 

 importance to the theoretical expressions which are mingled with 

 them in the original account " (" Tides and Waves," paragraph 

 415). To this Mr. Russell subsequently replied :— " . . . there is 

 an irresistible body of evidence in favour of the conclusion that 

 Mr. Airy's formulae do not present anything like even a plausible 

 representation of the velocity of the wave of the first order, and 

 that the formula I have adopted does as accurately represent them 

 as the inevitable imperfections of all observations will admit. It 



