upon the Phenomena, of Earthquakes, 191 
pagated, was the same, being at least equal to that of sound; 
for they all followed immediately after the noise that preceded 
them *, or rather the noise and the earthquake came together: 
and this velocity agrees very well with the intervals between the 
time when the first shock was felt at Lisbon, and the time when 
it was felt at other distant places, from the comparison of which 
it seems to have travelled at the rate of more than twenty miles 
per minute ft. 
17. An historical account of the earthquakes which have hap- 
pened in New England f, says, that, of five considerable ones, 
three are known to have come from the same point of the com- 
pass, viz. the north-west: it is uncertain from what point the 
other two came, but it is supposed that they came from the 
same with the former. The velocity§ of these has been much 
less than that of the Lisbon earthquakes: this appears from the 
interval between the preceding noise, and the shock, as well as 
_ from the wave-like motion before mentioned. 
18. All the greater earthquakes, that have been felt at Ja- 
maica ||, seem, by the accounts given of them, to have come from 
the sea, and, passing by Port-Royal, to have gone northwards. 
The velocity of these also was far short of the velocity of the 
Lisbon earthquakes. 
19. The earthquake of London , on the 8th of March 1750, 
was supposed to move from east to west. I. have been credibly 
informed, that the same thing happened ina slight shock which 
was felt there in the last century, as. the person who told me 
this had an opportunity of observing; for, being, by accident, in 
a scalemaker’s shop at the time when it happened, he found 
that all the scales vibrated from east to west. 
20. All the shocks that have been lately felt at Brigue in 
Valais have likewise come ‘rom the same point of the compass, 
viz. the south **, 
21. Fifthly, The great Lisbon earthquake has been succeeded 
by several local ones since, the extent of which has been 
much less. 
* See Philos. Trans. vol. xlix. p- 414; or Hist. and Philos, of Earthq. 
p. 515. 7 See art. 97. t See Philos. Trans, vol. 1. p- 9. 
§ As in some earthquakes the velocity with which they are propagated 
is much less than in others, it is evident that they can by no means be 
owing to avy cause residing inthe air: for any shock communicated to the 
air must necessarily move with a velocity neither greater nor less than that 
of sounds; that is, at the rate of about thirteen miles per minute, 
|| See the accounts of them in Philos. Trans. No. 209; or vol. ii—Lo-- 
thorp’s Abr. p. 410, &c. 
€ See Hist. and Philos. of Earthq. p. 250; or Philos, Trans. vol, ¥— 
Martyn’s Abr. Meteorology, passim. 
** See Philos. Trans. vol. xlix. p.620. The same has been observed ot 
Smyrna also, sce Philos. Trans, No. 495; or Martyn’s Abr, vol. x. p. 526. 
22, Such 
