(520 Correspondoice — A. H. Hunt. 



After my August paper was in type, Mrs. S. Ayrton expounded 

 the subject of ripple-mark at the soiree of the Eoyal Society, and 

 subsequently delivered a lecture at Cambridge under the auspices 

 and special sanction of Section G. 



In the course of the latter lecture Mrs. Ayrton ignored all previous 

 enquirers, except Professor Darwin, whom she considered not to 

 have fully appreciated the significance of his own experiments. 

 This places me in a difficulty, as I am in doubt whether Mrs. Ayrton 

 has considered the work of modern writers, or only the views 

 expressed in the older text-books. Then there is another difficulty, 

 and that is, that the subject was considered by Professor Osborne- 

 Reynolds' Committee on Tides and Waves, which was a Section G 

 committee ; while the subject comes within the purview of the 

 reappointed Committee on 'J'errestrial Waves, etc. As a matter of 

 fact, Mrs. Ayrton's views, as endorsed by the Royal Society and 

 Section G, are in conflict with the views accepted by two committees 

 of the British Association and of all modern workers. Indeed, 

 Mrs. Ayrton uses the words " Contrary to accepted opinion." 



I am aware that Bacon declares that unanimity is a very dangerous 

 thing, and that, theoretically, it might be safer for me to differ from 

 Professors Darwin and Osborne-Reynolds, and Dr. Vaughan Cornish, 

 who are the modern authorities who have dealt more particularly 

 with the sand-ripples of tidal and other continuous currents ; but, 

 except in some microscopic points of details, there seems to me to 

 be no room for doubt. 



During the past months of September and October I had the 

 little Moorland stream, the river Bovey, under close observation, 

 and for eight weeks one particular sand-flat was more or less 

 rippled. 



Mrs. Ayrton maintains that a steady current cannot produce 

 sand-ripples, and suggests that certain sand- waves on the Goodwin 

 Sands are caused by stationary sea- waves. So far as my observation 

 goes, there are no stationary waves in the open sea ; and it is 

 an uncontrovertible fact that a steady current, as understood by 

 geologists, viz., a current flowing to all outward appearances 

 continuously in the same direction, can, under certain conditions 

 of speed, depth, and composition of bottom, form sand-ripples, as 

 pointed out by Dr. Sorby, F.R.S., in 1859. 



The point that geologists want decided is whether the sand-ripples 

 proved by Monsier Siau in the Indian Ocean, in a depth of over 

 100 fathoms, were produced by continuous currents or by wave-action. 

 A good deal turns upon the answer. To me the balance of evidence 

 seems to be in favour of wave-action, because, as a rule, deep 

 currents do not disturb the bottom, but slide over the strata of water 

 which are in contact with the bottom ; but I come to that conclusion 

 in face of the fact that under certain circumstances continuous 

 currents have been proved to ripple a sandy bottom. 



I should like to see a committee appointed, to consist of all 

 the leading workers who have written upon ihe subject of current 

 ripple-mark, and especially of those who have delivered popular 



