192 Conjectures concerning the Cause, and Observations 
22, Such were the earthquakes in Switzerland ; those on the 
borders of France and Germany; those in Barbary, &¢.* 
Sxcrion I]. —23. How well soever these facts may agree with 
the supposition before laid down, That. subterraneous fires are 
the. cause of earthquakes, one doubt, however, may perhaps re- 
main; viz. how it is possible that fires should subsist, which have 
no communication with the outward air? In answer to this; I 
might allege the example of green plants, which. take fire by 
fermentation, when laid together in heaps; where the admission 
of the outward air is so far from being necessary, that it will ef+ 
fectually prevent their doing so. . But, to pass by this, we have 
many instances more immediately to the purpose, 
24. It can hardly be supposed, that the fires of the generality 
-of voleanos receive any supply of fresh air (for this must effee- 
tually be prevented by that vapour, which is continually rushing 
out at-all their vents), and yet they subsist, and frequently even 
increase, for many ages. Now, these are fires of the very same 
kitid-with these which I suppose to be the cause of earthquakes. 
Other facts, still more expressly to the purpose, are as follow: 
_ 25. In the earthquake of the Ist of November 1755, we are 
told that both smoke and light flames were seen on the coast 
of Portugal, near Colares; and that, upon oceasion of some of 
the succeeding shocks, a slight smell of sulphur was perceived to 
accompany a “ fog, which came from the sea, from the same 
quarter whence the smoke appeared f.” 
26. In an account of an earthquake in New England, it is 
said, that. at Newbury, forty miles from Boston, the earth opened 
and threw up several cart loads ef sand and ashes; and that the 
sand was also slightly impregnated with sulphur, emitting a blue 
flame when laid on burning coals {. 
_ 27. One of the relaters of the earthquake in Jamaica in 1692 
has these words: ‘¢ In Port-Royal, and in many places all over 
the island, much’ sulphireous combustible matter hath been 
found (supposed to have been thrown out upon the opening of 
the earth), which, upon the first touch of fire, would flame and 
burn. like a candle. ... 0 4.4, 
28. “ St, Christopher’s was heretofore much troubled with 
earthquakes, which, upou the eruption there of a great mountain 
of combustible matter, which still continues, wholly ceased, and 
have never been felt there since §.” 
29. Again, we are told, that, on the 20th November 1720, 
* Sco tlic accounts of these collected together in Philos. Trans. vol. xlix; 
or in the Hist. and Philos, of Earthq. 
+ Sce Philos. Trans. vol. xlix. p. 414, &e. 
¥ See Philos. Traus. No. 409; or vol. vi. part ii. p. 201.—Eames’s Abr. 
§ See Philos. Trans. No. 209; or vol. ii. p, 418,—Lowthorp’s Abr. 
a burning 
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