.265 Profefor WitLtAMs on Earthquakes. 
was obferved by thofe that were abroad; that as the fhake paffed 
„under them, the furface of the earth fenfibly rofe up, and then 
funk down again ; which muft have produced an undulation of 
the earth, or a motion like that of a wave, both perpendicular 
and horizontal ; firft rifing in a perpendicular dire&ion, and as 
it fubfided, fpreading itfelf in a horizontal direction all around. 
"The nature, therefore, or Zimd of the motion, was undulatory. 
The violence of the fhock, like that of the other great earth- 
quakes, was fuch as to caufe the houfes to fhake and rock, as if 
they. were. falling. to pieces. The; doors, windows, and mov- 
ables, . made 4 a fearful clattering. ‘The pewterand:china were 
thrown from their fhelves. Stone walls, and the tops of feveral 
chimnies were (haken down. In fome places, the doors were 
unlatched and burft open, and people in great danger of falling. 
There vere various opinions as to the duration of this earth- 
quake." i The moft probable is, that the fhake began about half 
@ minute after the roar was firft heard, and rofe to its greateft 
height i in about a minute more ; and was about half a minute 
in goi > off. Whence, the duration may be fuppofed to have 
‘been about twominutes. It was very generally agreed, that the 
courfe of this earthquake was from north-weft to fouth-eaft. 
^* The noife and íhakes, it is faid, feemed to come from the 
** north-weltward, and to go of fouth-eafterly ; and fo the 
** houfes feemed to reel.” This account of its courfe, was 
confirmed by all the ome one or two excepted, which. differ 
fo much from one another, that nothing can be determined, 
from them. . _ With regard. to the mits of this earthquake, it 
xtended dos the.river Delaware, in Pennfyloania, fouth-weft,: 
to Kennebeck, north-eaft. At both thefe places it was fenfibly’ 
f. Mong the. fhake \ was but fal, Its E therefore, 
& 
CE aes 
