226 I4etv Olservations on Volcanoes and their Lavas. 



merly than they are at present. The surface of our conti- 

 nent is covered with them in various places. The peninsula 

 of Italy, and the neighbouring islands, show a very great 

 number of them, four of which only are still burning, and 

 they are the only volcanoes in activity in a circumference of 

 6 or 700 leagues, although there must have been plenty of 

 them in the countries and seas comprised in this space. This 

 fact is so well known at present that I shall cite only one 

 example, taken from the Travels of M. Horneman in the 

 North of Africa. 



He remarked in his route between Audjela and Moursouk 

 several mountains with all the characteristics of antient vol- 

 canoes. This class of mountains was little known to him., 

 and his recital, therefore, wants precision ; but his language 

 admits of no doubt. There are, he says, many chains of 

 black and steril mountains. He remarked one which had 

 the form of a truncated cone. He saw basaltes, stones of 

 a red colour like bricks, porous and spongy stones resem- 

 bling the scoria2 of metals, dull and heavy stones, and others 

 full of holes and cavities ; characters which cannot be 

 mistaken for any thing else than volcanic productions. 

 M. Horneman also learned at Moursouk, that there were 

 black mountains upon the route leading from this city to 

 Bornon towards the south-east. 



The Lesser Antilles, the Mariannes, the Aleoutes between 

 Kamtschatka and America, the Fero Islands, and the nu- 

 merous islands of the South Sea, are all volcanic produc- 

 tions, and a few among them are still burning. 



This is one of the many proofs that the causes which have 

 produced the changes upon our globe have much diminished, 

 and that it constantly tends to a more stable and fixed state. 

 For although the volcanic mountains of the interior of the 

 earth have only burned under the water of the antient sea, and 

 it may be possible that some of them would have experienced 

 eruptions if the sea again washed them ; it is without doubt, 

 from the numerous examples afforded by the seas of the pre- 

 sent day, that a great number burn no longer after the sea 

 huS withdrawn. 



When M. Dolomieu, who has so well described several 



volcanic 



