Hunt — On the Action of Waves on Sea-heaches, 8fc. 271 



1837, p. 448). Mr. Kinahan has defined a ground-swell as a wave 

 generated in the Atlantic or Channel, as distinguished from a wave 

 due to the winds blowing directly on the coast — {Travelling of 

 Sea-heaches^ loc. cit. p. 3). 



Mr. (now Sir James) Douglass has referred the travel of shingle 

 to the ocean wave, or ground-swell (P. 45). 



Mr. E. Wynne describes Portland as exposed to the full swell 

 of the Atlantic rollers, and considers the said Atlantic rollers might 

 be transformed into waves of translation in the Channel (P. 47). 



If the ground-swell be the offspring of a wave of oscillation, it 

 is difficult to see how it is to be distinguished from the ordinary 

 swell, whose action on a beach we have been considering. Nor is 

 it easy to see how it can exert more power than its parent wave. 

 The term conveys the impression that an ordinary swell is meant, 

 travelling in water shallow enough for it to feel the bottom ; but I 

 can find no such definition of it. The term is often vaguely under- 

 stood, which I perceived when an intelligent man described to me 

 the effect on the sea-bottom of an "under-ground swell." 



It may be noted, that Mr. Kinahan's long waves of irregular 

 period cannot be ordinary swells resulting from oscillating wind- 

 waves, as their periods are too long and irregular. A few years ago, 

 at one of the British Association lectures, it was confidently asserted, 

 that any wave with a period exceeding twenty seconds must be at- 

 tributed to some other cause than an ordinary wind-wave. 



Many observers, whilst watching the tide rising on the sea- 

 shore during stormy weather, must have been surprised to note the 

 long time that occasionally elapses before the waves reach a given 

 point on the beach a second time. Thinking to observe the rise 

 and fall of irregular waves of this sort best by the currents set up 

 by them in the mouth of an artificial harbour, I made the following 

 observations on February 2nd, 1883, in the mouth of the old har- 

 bour at Torquay. 



The following is the substance of my notes : — 



On the night of Feb. 1st it blew a heavy gale from the southward. 

 On Feb. 2nd I went to the Old Pier Head to observe if there were 

 any " run " in and out of the harbour. I moored a piece of wood 

 about five inches long to a stone, sunk in the harbour's mouth, by a 

 line sufficiently long to allow the wood to pass freely through the 

 space of several yards on the surface of the water. High- water 



