TIDES AND WAVES 175 



appointed a committee to apply it, and the result was 

 its publication of G. H. Darwin's standardisation. 

 When the British Admiralty in the preparation of 

 its tide-tables does not use the methods of Kelvin 

 and Darwin, it uses either those of Lubbock and 

 Whewell or developments of them. The achieve- 

 ments referred to stand out as landmarks in the 

 history of the subject, but the Association has from 

 time to time rendered assistance to other workers 

 on the subject. 1 



The subject of water-waves engaged the attention 

 of the Association in the year 1837, and a committee 

 was appointed to report on the matter. The work 

 fell to Scott Russell, who produced two elaborate 

 and valuable reports, printed in the annual volumes 

 for 1838 and 1844. These include a number of 

 interesting experiments and acute observations ; in 

 particular the characteristics of various leading 

 types of waves are analysed with great sagacity. 

 The work is the more remarkable in that it was 

 accomplished with little aid from mathematical 

 theory, which was then in its infancy. Two con- 

 spicuous anticipations of later discoveries may be 

 mentioned, viz. the distinction between wave- 

 velocity and group-velocity, and the minimum 

 velocity of capillary waves. The reports, which 

 may still be consulted with advantage, are also of 

 historical interest in relation to subsequent theo- 

 retical work of Stokes and others. 2 The practical 

 connexion between these investigations and KusselPs 

 work on the form of ships will be noticed elsewhere. 



1 Dr. J. Proudman. 2 Prof. H. Lamb. 



