332 Conjectures concerning the Cause, and Observations 
80. As the most extensive earthquakes generally proceed from 
the lowest countries, but especially from the sea, so those of a’ 
smaller extent are generally found amongst the mountains : hence 
it almost always happens, that earthquakes, which are felt near 
the sea, if at all violent, are felt also in the higher lands; whereas 
there are many amongst the hills, and those very violent ones, 
which never extend themselves to the lower countries. ‘Thus 
we are told, that, at Jamaica, ‘* shakes* often happen in the coun- 
try, not felt at Port- -Royal; and sometimes are felt by those that 
live in and at the foot of the mountains, and by no body else.” 
On the other hand, the earthquake that destroyed Port-Royal 
extended itself all over the island: and the same was observed of 
a smaller earthquake, that happened there in 1687-8; which 
latter undoubtedly came from the oe as appears by Sir Hans 
Sloane’s account of it +. 
81. Earthquakes of small extent are also very common amongst 
the mountains of Peru and Chili. Antonio d’Ulloa says, ** Whilst 
we were preparing for our departure from the mountain Chichi- 
Choco, there was an earthquake which was felt four leagues 
round about: our field tent was tossed to and fro by it, and the 
earth had a motion like that of waves; this earthquake, how- 
ever, was one of the smallest, that commonly happen in that 
country.” The same author tells us, in another place, that, 
“¢ during his stay at the city of Quito, or in the neighbourhood 
of it, there were two earthquakes, violent enough to overturn 
some houses in the country, which buried several persons under 
_ their ruins.” 
Secrion V.—82. It is generally found, that earthquakes in 
hilly countries, are much more violent eh those which happen 
elsewhere; and this is observed to be the case, as well when they 
take their rise from the lower countries, as amongst the hills’ 
themselves. This appearance being so easily to be accounted 
for, from the structure of the earth already described, I shall 
content myself with establishing the certainty of a fact, which 
tends so greatly to confirm it. 
83. The earthquakes that have infested some of the towns in 
the neighbourhood of Quito, have not only been incomparably 
more violent than that which destroyed Lisbon, but they seem to 
have exceeded that also which destroyed Lima and Callao. In 
* This is taken from an account of the earthquake that happened at Ja- 
maica in the year 1692, which, as well as some others before mentioned, 
was _attended with the wave and previous retreat. See Philos. Trans. 
No. 209, or Lowthorp’s Abr. vol. ii. p.417 and 418. 
t+ See Phil. Trans. No. 209, or Lowthorp’s Abr. vol. ii, p. 410. 
Lisbon, 
