On Earthquakes and extraordinary Agitations of the Sea. 45 



in the expression for V which contain cos great, I obtained cor- 

 responding values of a— or } and a 1 — er r In case qc be small, 



these values involve as a factor -~ -f — ~ — - t and consequently, 



since ——r. — - is wholly periodic, only indicate a tendency of the 



action of the waves to produce vibrations of the sphere. For 

 this reason the results can in no case have any bearing on the 

 main object of my present researches, and I have therefore not 

 thought it worth while to exhibit them. It may, however, be 

 mentioned, as being confirmatory of the correctness of the mathe- 

 matical processes I have employed, that the investigation relative 

 to the term involving qr cos qicat, led to results respecting the 

 mutual action of the sphere and fluid in accordance with those 

 obtained by the usual treatment of the problem of the resistance 

 of the air to a ball-pendulum. But, for reasons which I need 

 not now repeat, I am of opinion that both these solutions relate 

 to circumstances of the motion different from those contemplated 

 in the problem which has been under discussion in this commu- 

 nication. 



Cambridge, December 21, 1865. 



VI. On Earthquakes and extraordinary Agitations of the Sea. 

 By Richard Edmonds, Esq,* 



AS no account of the extraordinary disturbance of the sea at 

 Plymouth and Penzance on the 14th of October, 186.2, 

 has yet appeared except in the newspapers, I desire now to 

 record it. 



Accompanied by a thunder-storm, as usual with such dis- 

 turbances, it was first observed about sunrise, when the sea in 

 each place rose four or five feet above its proper level, and the 

 alternating current (rushing in and rushing out) was so strong 

 and of such long continuance in Plymouth that the large iron 

 buoy outside the gates of the Great Western Docks was fre- 

 quently, to the astonishment of the beholders, completely sub- 

 merged ; and the gates could not be shut all that day, nor during 

 the following night. The same morning at 7.30, in the Truro 

 river (a branch of Falmouth harbour), "when the tide had been 

 ebbing there about three hours, and had almost left the wharf 

 occupied by Mr. John James, a sudden wave or ' bore ' came up 

 the river, the water rising from three to four feet, and coining up 



* Read before the Royal Geological Society of Cornwall, on the 2^lth of 

 October, 1865, and communicated by the Author. 



