﻿40 Mr. R. Edmonds on Extraordinary Agitations of the Sea. 



tide-gauge ; but the great wave was not observed until twenty- 

 four minutes past 7 on the same morning. The first indication 

 at Newcastle was at two minutes past 7 in the morning ; two 

 hours afterwards a pretty full wave was noticed, and five hours 

 afterwards was the greatest disturbance of all. On the coast of 

 New Zealand the time extended from about 5 a.m. of the 15th 

 of August to nearly an hour after noon." 



All this very strikingly coincides with the agitations in the 

 Scilly Isles, Mount's Bay, Falmouth, and Plymouth on Whit- 

 sunday, the 23rd of May, 1847. That in Mount's Bay was 

 noticed as early as 5 a.m., and continued all day with varying 

 magnitude, the rise and fall having been from 3 to 5 feet or more 

 perpendicularly. In the night preceding, a slight tremor of the 

 earth was felt in Mount's Bay by two coastguardsmen while 

 standing on the cliff between Newlyn and Mousehole ; and " a 

 strange noise as if underground was heard " at Scilly about the 

 time of the oscillation of the sea there. The disturbance was at 

 its maximum in Mount's Bay at 5 p.m., and in Plymouth be- 

 tween 8 and 9 p.m., and did not cease until the following day, 

 when a more fearful movement of the sea, lasting several hours, 

 occurred in Peru in the harbour of Callao ; and " a furious sub- 

 marine earthquake was felt by the captain of the American whale 

 frigate ' Acushuett' about sixty miles W.S.W. from the island 

 of San Lorenzo, at 3 a.m. of the 24th"*. These extraordinary 

 oscillations of the sea in the west of England twenty-one years 

 ago appear, therefore, in duration, magnitude, and varying mag- 

 nitude, to bear a very close resemblance to those of the present 

 year in Australia and New Zealand. 



Having already shown how these extraordinary disturbances 

 of the sea may be produced by local submarine shocks, I will 

 now state how they may, during their continuance, become of 

 greater magnitude at one time than at another. This may result 

 from a subsequent shock coinciding with one of the effluxes, 

 and thus making that efflux considerably greater than it would 

 otherwise have been. The following influx would therefore 

 rise proportionally higher on the beach than did the influx which 

 preceded it. 



It thus appears that the recent extraordinary agitations of the 

 sea in Australia and New Zealand, as well as in Peru and Cali- 

 fornia, were all produced, not by any great disturbance of any 

 kind in mid-ocean, but by local shocks of the submarine ground 

 upon or near which, in each locality, the agitated waters had 

 previously rested. 



Plymouth, December 1868. 



* British Association Report for 1850, (Sections) p. 82. 



