TRUE VOLCANOES. 393 



in this enumeration, I think I may venture to consider the 

 lowest limit of the number, were simultaneously in action, 

 their influence on the condition of the atmosphere, and its 

 climatic, and especially its electric relations, would certainly 

 be extremely perceptible ; but as the eruptions do not take 

 place simultaneously, but at different times, their effect is di- 

 minished, and is confined within very narrow and chiefly 

 mere local limits. In great eruptions there occur around the 

 crater, as a consequence of the exhalation, volcanic storms, 

 which, being accompanied by lightning and torrents of rain, 

 often occasion great ravages ; but these atmospheric phenom- 

 ena have no generally extended results. For that the re- 

 markable obscurity (known by the name of the dry fog) which 

 for the space of several months, from May to August of the 

 year 1783, overspread a very considerable part of Europe 

 and Asia, as well as the North of Africa — while the sky was 

 seen pure and untroubled at the top of the lofty mountains 

 of Switzerland — could have been occasioned by the unusual 

 activity of the Icelandic volcanicity, and the earthquakes of 

 Calabria, as is even now sometimes maintained, seems to me 

 very improbable, on account of the magnitude of the effect 

 produced.* Yet a certain apparent influence of earthquakes, 

 in cases where they occupy much space, in changing the com- 

 mencement of the rainy season, as in the highland of Quito 

 and Riobamba (in February, 1797), or in the southeastern 

 countries of Europe and Asia Minor (in the autumn of 1856), 

 might, indeed, be viewed as the isolated influence of a volcanic 

 eruption. 



In the following table the first figures denote the number 

 of the volcanoes cited in the preceding pages, while the sec- 

 ond figures, inclosed in parentheses, denote the number of 

 those which in recent times have given evidence of their ig- 

 neous activity. 



Number of Volcanoes on the Earth. 



I. Europe (above, p. 328, 329) 7 (1) 



II. Islands of the Atlantic Ocean (p. 329-332) 14 (8) 



III. Africa (p. 332-331) 3 (1) 



IV. Asia— Continental 25 (15) 



(1) Western and Central (p. 331-310) 11 (6) 



(2) The Peninsula of Kamtschatka (p. 310-311). 11 (9J 

 V. Eastern Asiatic Islands (p. 311-351) 69 (51/ 



[* A similar fog overspread the Tyrol and Switzerland in 1755, just 

 before the great earthquake which destroyed Lisbon. It appeared to 

 be composed of earthy particles reduced to an extreme degree of fine- 

 ness. — Tr.] 



R 2 



