and Volcame Substances. P11 
reasoning is conformable to matter of fact within our know- 
ledge. 
i. The floetz or horizontal strata, bear indubitable marks 
of having been deposited, from aqueous suspension. 
2. We know of innumerable mountain eminences owing 
to the indisputable action of subterranean fire : volcanic 
mountains raised in continents, and islands out of the ocean: 
and peaks of lava-basalt formed by sudden cooling. 
Being bound therefore to explain the unknown phenome- 
na, by the known, we are compelled to acquiesce in the 
reasoning here advanced. — With these preliminary remarks, 
I proceed to shew, that The Fletz-Trap formation of the 
Wernerians, 1s of igneous origin, and comes under the head 
of volcanic ejections. 
VOLCANOES, are natural vents in the crust of the 
earth, made by subterranean fires, to afford an exit for the 
gasses, vapours, and solid substances that have been ex- 
posed to the action of intense heat in the bowels of the 
earth. 
Volcanoes are active, or extinct. 
Active volcanoes may be considered as those which have 
manifested conflagration and discharge of ignited matter 
within a céntury of the present time. Prof. Youngin avery 
interesting article on volcanoes in Rees’ Encyc. expresses 
the opinion that the number of active volcanoes is near one 
thousand. Werner reckoned them at one hundred and 
ninety three. Brieslak, after M. M. Leonhard, Kopp, and 
Gaertner in their prospectus of mineralogy in 1817, at one 
hundred and eighty-seven only : viz. fifteen in Europe, six- 
ty-two in Asia, ten in Africa, ninety-four in America, six in 
Australasia 3 of which one hundred and eighty-seven, nine- 
ty five are situated on continents, and ninety-two on islands: 
3 Breis. 403. D’Aubuisson reckons up two hundred and 
five, of which one hundred and seven are onislands. But 
from Lieut. Gov. Raffles’ account of Java, and his remarks 
on the Celebes and Philippine islands to the east of Java, 
there is good reason to believe we may add to that number 3 
but we are not yet able to enumerate more from actual ob- 
servation. 
‘The seat of volcanoes, by commion consent of the latest 
and best observers, is within or below the oldest granite. 
2 Spalanz. trav. jee 165, at Montemulo 3 ib. 235. eu 
