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tains ; which ceafe, and begin again at every great 
preflure. This phenomenon is common to many 
places in this ifland. The explanation of it is eafy ; 
but the following is what I particularly obferved. 
As I walked within about forty paces from the 
brink of the fea, where the waves broke, I perceived, 
in one place, the plants were much agitated by fome 
caufe, that was not yet apparent. I drew near, and 
difcovered a hole about fix feet deep, and half a 
foot diameter ; and flopping to confider it, I per- 
ceived the earth tremble under my feet. This in- 
creafed my attention ; and I heard a dull kind of 
noife underground, like that which precedes com- 
mon earthquakes ; which I have obferved many a 
time. It was followed by a quivering of the earth ; 
and after this a wind iffued out of the hole, which 
agitated the plants round about. I watched to fee 
whether the motion extended to any diftance ; but 
was fenfible it did not reach above three or four 
paces from the hole, and that no motion was per- 
ceived farther off. 
I further obferved, that this phenomenon never 
happens till after the feventh wave rolls in ; for it is 
a common thing in this country to find the fea ap- 
pear calm for fome time, and then to produce feven 
waves, which break upon the coaft one after an- 
other : the firft is not very confiderable ; the fecond 
is fome what fbronger ; and thus they go on in- 
ereafing to the feventh, after which the fea grows 
calm again, and retires. This phenomenon of the 
feven waves is obferved by navigators with great at- 
tention, efpecially at low water, in order to be the 
better able to go in or come out at the very time 
that 
