190 Conjectures concerning the Cause, and Obserbations 
tleman there saw the ground rise like the sea in a wave, as the 
earthquake passed along, and that he could distinguish the ef- 
fects of it, to some miles distance, by the motion of the tops of 
the trees on the hills. Again, in an account of the latter, it is 
said, ‘the ground heaved and swelled, like a rolling swelling sea,” 
insomuch that people could hardly stand upon their legs by rea- 
son of it. 
13. The same has been observed in the earthquakes of New* 
England, where it has been very remarkable. A gentleman giving 
an account of one, that happened there the 18th November 
1755, says, the earth rose in a wave, which made the tops of the 
trees vibrate ten feet, and that he was forced to support himself, 
to avoid falling, whilst it was passing. 
14, The same also was observed at Lisbont, in the earth- 
quake of the Ist November 1755, as may be plainly collected 
from many of the accounts that have been published concerning 
it, some of which affirm it expressly: and this wave-like motion 
was propagated to far greater distances than the other tremulous 
one, being perceived by the motion of waters, and the hanging 
branches in churches, through all Germany, amongst the Alps, 
in Denmark, Sweden, Norway, and all over the British isles. ~ 
15. Fourthly, It is observed in places which are subject to 
frequent earthquakes, that they generally come to one and 
the same place, from the same point of the compass. - 1 may 
add also, that the velocity with which they proceed (as far 
as one ean collect it from the accounts of them) is the same; 
but the velocity of the earthquakes of different countries is 
very different. 
16. 'Fhus all the shocks that succeeded the first great one at 
Lisbon in 1755, as well as the first itself, came from the north- 
west{. This is asserted by the person who says he was about 
writing a history of the earthquakes there: all the other accounts 
also confirm the same thing; for what some say, that they came 
from the north, and others, that they came from the west, can- 
not be looked on as any reasonable objection to this, but rather 
the contrary. The velocity also, with which they were all pro- 
* See Philos. Trans. vol. 1. p. 1, &c. 
+ Sec the accounts collected together, in the xlixth volume of the Philos. 
Trans., or in Hist. and Philos. of Earthg. and particularly p. $15, where it 
is said, “ A most dreadful earthquake shook, by short but quick vibrations, 
the foundations of all Lisbon; then, with a scarcely perceptible pause, the 
nature of the motion changed, and every building was tossed like a waggon 
driven violently over rough stones, which laid in ruins almost every house, 
church, &c.” , 6 
For the wave-like motion at Oporto, see Phil. Trans. vol. xlix. p. 418: 
for the same at Gibraltar, see Hist, and Philos, of Earthq. p. 322 
t. Sve Philos. Trans. vol, xlix. p. 410. 
pagated, 
