Correspondence — A. R. Hunt. 429 



Sir George Airy observes that, "in the tide wave ami every 

 other wave which travels along a channel .... this law 

 is universal, that the water is travelling forward with its greatest 

 speed at the time of high water, or at the top of the wave" ("Tides 

 and Waves," art. 183). The flood-tide current usually flows from 

 'half flood' to 'half ebb'; and the ebb current ebbs from half ebb 

 to half flood. Thus, when Mr. Wheeler discusses the effect of the 

 flood-tide current it is most important to know exactly what is 

 meant ; for the water does not turn in direction until the tide has 

 been rising some three hours, unless affected by special circumstances. 



(3) Then there is another important source of confusion of ideas 

 among writers generally. The great tidal wave is often spoken of 

 as though a wave which, crossing the Atlantic, impinges on the 

 coasts of Eui'ope ; whereas of course the motion of the great tidal 

 wave is away from the British shores, travelling from east to west. 

 Thus no little confusion arises between the ideas of the great tidal 

 wave and the tidal currents which run in an out of our British 

 waterways. The generation of tidal wavelets of translation by the 

 flood-tide current, or any tidal current, is not in accordance with my 

 own experience at the seaside during the past fifty years. 



(4 and 5) These hypotheses are not confirmed either by my own 

 observations or experiments. 



(6) A proportion of wave length to height of only 3 to 1 is to 

 myself inconceivable. My boat was 26 feet long with a freeboard 

 of about 2 feet. I should not be writing this letter if one were 

 liable to encounter such waves or anything approaching them in the 

 English Channel. I should say that a length to height of 20 to 1 

 would be very excessive ; and that 40 to 1 would be much nearer 

 the mark. My friend Mr. Howard Fox, F.G.S., has himself observed 

 waves with a period of twenty seconds at the Lizard Signal Station. 

 These waves would be just over 2,000 feet long. Sir G. G. Stokes 

 records waves with a period of 17 seconds. 



It is true that Littoral Drift has a limited interest for geologists ; 

 but the action of waves on the coast, and on sea-bottoms to at 

 least a depth of 100 fathoms, aS'ords geological and pala3ontological 

 problems of very great interest indeed, so that it is advisable to see 

 that the foundations are securely laid. 



If any mathematician who can speak with authority would write 

 a little primer on wave-action, similar to Sir Archibald Geikie's 

 shilling Primer of Geology, it would be invaluable. For my 

 own instruction, when working and experimenting, I was entirely 

 dependent on the kindness of Lord Rayleigh, who was ever ready 

 to explain what I failed to understand ; and of Sir G. G. Stokes, 

 who worked out a special case for me, since published in the 

 Transactions of the Devonshire Association.' But, so far as my 

 experience goes, the information generally accessible to non- 

 mathematicians is, on this subject, worse than useless, being almost 

 invariably misleading. 



1 Trans. Devonshii-e Assoc, 1887, p. 512. 



