616 MR MILNE ON A REMARKABLE OSCILLATION OF THE SEA. 



The Firth of Clyde is another part of the coast where, most probably, the 

 phenomenon, if it had occurred, would have been noticed ; but no extraordinary 

 movement of the waters was perceived there. 



Inquiries were also made by me at Carlisle, Whitehaven, Ayr, Inverary, and 

 Belfast, at none of which places was any oscillation perceived. 



It would appear, therefore, that the only parts of England where the pheno- 

 menon occurred, was on the coasts of Cornwall and Devonshire ; and that, on the 

 opposite side of the island, it was seen only along the coast of Northumberland, 

 and the east coast of Scotland. 



OF PHE- II, I proceed now to offer some remarks as to the probable cause of the phe- 



OMBNON. nomenon. 



That it was produced by submarine earthquakes, I hold to be most impro- 

 bable. For if such had occurred, we would have obtained from other sources 

 some direct evidence of their occurrence ; and, moreover, other effects would have 

 been produced, which certainly did not occur. 



The oscillations into which the sea was thrown by the Lisbon earthquakes, 

 consisted of not more than two or three waves, corresponding probably with the 

 subterranean explosions or eruptions which took place ; and the flux and reflux 

 of tide thus occasioned, did not, at any of the coasts where it occurred, continue 

 longer than an hour. 



Here, however, the oscillations lasted three or four days ; so that, on the sup- 

 position of their having been caused by submarine earthquakes, it would be neces- 

 sary to suppose that explosions or eruptions had been going on for several days. 

 But it is scarcely possible to conceive that such could have occurred, without 

 producing shocks felt on the adjoining continents, and other effects equally un- 

 equivocal. Besides, it is exceedingly improbable, that eruptions or explosions 

 would continue so long at any one time or place. Farther, it is worthy of remark, 

 that at the time of the Lisbon earthquakes, not only was there an oscillation of 

 the sea, but the water in ponds and lakes was affected, by the concussion trans- 

 mitted through the earth's solid framework ; and some such appearances would 

 undoubtedly have been observed in July last, had the more extensive and pro- 

 longed oscillation which then occurred been produced by a similar cause. 



Before directly explaining my own views as to the true cause of the pheno- 

 menon, I shall refer to its occurrence on former occasions, as some of the accounts 

 appear to me to throw important light on this part of the subject. 

 CASES. (1.) On the 16th July 1749, the sea at Milford Haven flowed and retired 



seven times in a quarter of an hour. * 



1 Gentleman's Magazine. 



