The Causes and Flienomena of Earthquakes, 63 



earthquake sea wave, and the prolongation of phenomena argued 

 more in favour of the former than of the latter. It is within my 

 own knowledge, that long-continued south-westerly winds blowing 

 as they sometimes do for weeks and months, at the chops of the 

 British Channel will heap up the sea in places to 30 feet above its 

 usual level ; and I have known more than one instance of Poole 

 Harbour in Dorsetshire (on the shore of which I resided for 

 nearly seven years), which is in fact a vast inland salt water lake, 

 having remained full of water for more than two successive tides, 

 owing to the extraordinary ebb from Portsmouth running in and 

 preventing the Poole ebb from running out. So that such 

 occurrences there can be accounted for. 



It was clear that some deep disturbance, whether by earthquake 

 far away to the eastward in the ocean, or an unusually violent 

 Cyclone, produced the late disturbance. The sand mixed with 

 the harbour and river water proved the disturbance to have been 

 deep, so that, whatever the cause, it must have been violent. In 

 fact, it is known by observation and experiment that the sea is 

 affected to unknown depths. Mr. Mallet, who has discussed 

 certain similar occurrences in Europe, gives in no adhesion to 

 earthquakes as the normal original motive power. His words 

 are these — " It seems probable that in the great ocean such vast 

 nodal waves or rollers are frequently produced and propagated 

 to great distances from the regions of storms where they origi- 

 nate, and may simulate many of the phenomena of earthquake 

 great sea waves." (Report, 1850, p. 47.) 



Again, speaking of other kinds of oscillations, he says, " I am 

 disposed not to attribute such to earthquake shocks at all, but to 

 the sudden slippage under water of large masses of sub-marine 



bands of sand and mud Such a circumstance 



occurring upon a very moderate scale would be sufficient in a 

 narrow estuary to produce a wave o f tran slation liable to be 

 mistaken for the effect of an earthquake." (Id. p. 61.) 



These opinions of Mr. Mallet were controverted by Mr. Ed- 

 monds in a paper read before the Royal Geological Society of 

 Cornwall, 19th Oct , 1855, and afterwards published in the 

 Edinburgh Philosophical Journal, N. S. (Vol. hi. p. 285.) April, 

 1856. Mr. Edmonds says, the hypothesis was totally inapplica- 

 ble to facts relating te sea waves and earthquakes in Cornwall and 

 Devonshire in 1755, 1761, 1811, 1843, (July and October) and on 

 30th May, 1855. 



The effects of the passage even of a large and rapid steamer is 

 to produce a wave, which breaking on the shore very often pro- 

 duces effects that seem to a chance observer unaccountable ; 

 this I have already spoken of. Now, Dr. A M. Thomson and 

 myself were witnesses to a singular noisy commotion of waves in 

 a secluded harbour on the North Shore, at high water, on the 



