476 
GEOLOGICAL FEATURES OF OUR GLOBE. 
parts great depressions of the island have taken place. It 
also appears that this internal power has been displayed 
through the entire length of each line, with greater or less 
intensity in certain parts, as in the past year, when every 
portion of the globe seems to have shared those internal 
convulsions ; whilst a tidal wave was sweeping over much of 
the eartlPs surface, an internal one was apparently at the 
same time rolling round the central ocean, and by increased 
pressure communicating disturbance to each of those lines, 
violent earthquakes were shaking the islands of the Pacific, 
and the Peruvian coast sending huge waves northwards to the 
coast of California, at the very same time (1 5th August 1867), 
there was an earthquake at Gibraltar, recorded in the local 
paper of that date. The tidal wave reached the Chatham 
Isles on the same day, between 1 and 2 a.m., flowing inland 
four miles, and doing great damage ; it arrived on the 
New Zealand coast at 3 or 4 a.m., but at Sydney it was 
felt at 2.30 a.m., which is very remarkable, and seems to 
prove that it could not be the same Wave as that which 
visited the Chatham Isles, but must have been another com- 
mencing from the west coast of New Zealand. 
At Hilo, in the Sandwich Isles, it occurred on the 14th, 
15th, and 16th August, and at San Pedro, California, on 
the 15th; if it were the same wave which left the American 
shore that reached the Chatham Isles it was only fifteen and 
a half hours in traversing 6,300 geographical miles, and its 
velocity would be 400 miles an hour ; one great proof that it 
was not, is that there is no account of any of the low atolls 
or coral isles, which are far less elevated than the Chatham 
Isles, having been submerged, which must have been the 
case had it been so ; the probability is that there were several 
waves, and not one continuous one, each volcanic line having 
its separate one. 
These outbreaks of volcanic power seem to have a close 
connection with atmospheric disturbance by destroying the 
equilibrium between internal and external pressure ; thus, 
whenever a hurricane passes over one of these longitudinal 
fissures of the globe an earthquake is almost sure to be the 
result. 
