272 Mr Richard Edmonds on Earthquakes. 
continued, but with gradually decreasing violence, until low- 
water. A fisherman came in to the harbour in his boat an hour 
after the commencement of the agitation ; and, from the calm- 
ness of the sea at the pier head, had no suspicion that there 
was any run within the pier, until some persons on shore 
called to him that it was dangerous to land ; and presently, 
as he entered the inner basin, one of the influxes carried his 
boat along with great impetuosity for a hundred yards to- 
wards the northern shore, and, retiring, left it dry on the 
beach.” 
The phenomenon is likewise described as it occurred in 
other parts of the bay, after which the writer observes :— 
«Tt is remarkable that, in the recent disturbance in this 
bay, the agitation of the sea was apparently confined to a 
short distance from the shore, and at Portleven did not ex- 
tend even to the pier-head. With a view to account for this, 
let us suppose that an upward shock takes place at the bot- 
tom of the sea, a few leagues from our coast, and that a 
shoal with one of its sides perpendicular to our shore is 
thereby made to vibrate. The shock thus communicated to 
the water will be transmitted with a velocity much greater 
than that with which sound travels through air, and may 
cause the water along the shore to rush up the beach in the 
same manner as a smart blow at one end of a line of marbles 
causes the marble at the opposite end to fly off, whilst all 
the others remain stationary. When this body of water 
falls back to the stationary or less disturbed part of the sea, 
it will, by the reaction, be driven a second time up the beach ; 
and thus the fluxes and refluxes, like the motion of a pendu- 
lum, may continue for a long time, although originated by a 
single shock. 
Agitations beginning with an influx may be thus accounted 
for ; but they generally commence with an efflux, which may be 
produced by the inclined plane descending from the coast be- 
ing made to vibrate by a shock upwards: the effect of 
which would be to drive a considerable body of water sea- 
ward. 
The irregularity which often attends these oscillations 
may arise from a subsequent shock interfering with the 
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