Hecror.—On Earthquakes and Wave Phenomena. Al 
with slightly abated intensity, in five hours more. This gives the average 
velocity at a little over 290 feet per second between the Chatham Islands, 
and 360 feet per second from New Zealand to Australia, supposing that 
these places lie in the direct line of its progress. 
From the ratio which this shows of increased velocity and diminished 
amplitude of the wave, a rough approximation of the distance from New 
Zealand at which the wave originated is obtained, and indieates it at over 
3,000 miles.. If the earthshock, which originated at the same time with the 
wave, had reached us, owing to its greater velocity it would have travelled 
the same distance in less than half an hour, and been felt about ten hours 
before the sea wave was observed. 
As compared with the speed at which oceanie waves have been discovered 
to cross the Northern Pacific, this velocity is much less, and may be due to 
the Southern Ocean having an inferior average depth. 
I may remark that if efficient means were provided for the exact observa- 
tion of sueh phenomena, we should be able to arrive at the solution of very 
important facts in physical geography, as from such waves we might deter- 
mine the.depth of the ocean and from the earthquake shock we could 
arrive at the nature of the rocks which form its floor. It is by the latter 
means alone that we can ever hope to learn anything of the geological 
structure of the great proportion, amounting to nearly three-fourths, of 
the whole surface of the earth which is covered by the waters of the sea. 
With respect to the direction in which the wave we are considering 
appears to have travelled, the reported circumstance of its reaching Sydney 
and Adelaide at the same time, while it does not seem to have been observed 
at Melbourne, (most likely owing to the expanded form of the harbour, and 
the shelter afforded by Tasmania, where it was severely felt from the south- 
east), and lastly, its not having affected the inner parts of Auckland Harbour, 
indicate that its course was from south of east. 
I wish further especially to call attention to the rumours that there has 
been a recent rise of the land in this harbour, and that the tide does not now 
rise to its proper limits; on the other hand, that it falls lower than it formerly 
did with the same state of the tides. This has been connected with the 
occurrence of the ocean waves, but it is to the slight earthquake shock which 
we experienced that we must refer as the cause of the change in the level, if 
it has really taken place. I have carefully examined many points of the 
shore of the harbour, but have failed to satisfy myself that a change has 
recently taken place; but the subject is one requiring further exact observa- 
tions, extending over several periods of spring tides, before any conclusions 
ean be arrived at. i; 
Any elevation, however slight, occurring in such a mild manner, will 
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