1824.] On the Volcanos at present in Activity. 201 



Article XI. 



An Account of the Volcanos at present in Activity. 

 By M. Arago.* 



Some persons having appeared desirous of seeing in the 

 " Annuaire " an account of the volcanos now in activity, I 

 engaged to write it, but without having sufficiently reflected, as 

 I afterwards discovered, on the difficulty of this work. The 

 details with which most travellers have furnished us on these great 

 phenomena are incomplete, and extremely vague. In the esti- 

 mation of one, those parts of the earth from which a little smoke 

 arises, or upon which a few sparks are perceived, are volcanos ; 

 another gives this name only to mountains which incessantly 

 cast forth torrents of lava, burning matter, and ashes. The 

 first will insert in his catalogue the trifling flames of Pietra-Mala, 

 Barigazzo, Yelleia, of Persia, and Caramania ; the second 

 will place Santorini itself in the class of solfaterras. To this diffi- 

 culty must be added the still greater one of determining what 

 distance should separate two craters, that they may be considered 

 as two distinct volcanos. At TenerifFe the eruption of 1706 

 broke out at an opening two leagues distant from the Peak ; 

 that which destroyed Garachico burst out at an opposite side, 

 and at a point a league and a half distant from the Peak ; there 

 were then three leagues and a half between the two openings 

 without their being considered as belonging to two distinct vol- 

 canos. But, shall we consider the isle of Palma, where there 

 was an eruption of lava in 1699, as containing a volcano separate 

 from that of TenerifFe? Ought the destruction of a third of the 

 isle of Lancerote in 1730 to be considered as the effect of a 

 lateral eruption of the volcano of the Peak, or of a separate 

 volcano ? Analogous questions present themselves at every step, 

 and the means are wanting to answer them. I should, therefore, 

 have omitted printing this notice in the Annuaire, from which it 

 is desirable to exclude every thing that does not possess a cer- 

 tain degree of precision, if I had not had the advantage of con- 

 sulting the two persons to whom the physical history of the 

 globe is best known, MM. de Humboldt, and Leopold de Buch. 



Volcanos of Europe and the adjacent Islands. 



Vesuvius ; kingdom of Naples. 



Etna; Sicily. 



Stromboli ; Eolian islands. 



Hecla; Iceland. 



Krabla ; northern part of Iceland. 



Katlagiaa-Jokul ; Iceland. 



" From L'Annuair* pourl'an 1824. 



