550 HISTOEY OF GEOLOGY. 



of the New World, from 1799 to 1804. He remarked 1 the linear dis- 

 tribution of volcanic domes, considering them as vents placed along 

 the edge of vast fissures communicating with reservoirs of igneous 

 matter, and extending across whole continents. He observed, also, the 

 frequent sympathy of volcanic and terremotive action in remote dis- 

 tricts of the earth's surface, thus showing how deeply seated must be 

 the cause of these convulsions. These views strongly excited and 

 influenced the speculations of geologists ; and since then, phenomena 

 of this kind have been collected into a general view as parts of a 

 natural-historical science. Von Hoff, in the second volume of the 

 work already mentioned, was one of the first who did this ; " At least," 

 he himself says, 2 (1824,) "it was not known to him that any one 

 before him had endeavored to combine so large a mass of facts with 

 the general ideas of the natural philosopher, so as to form a whole." 

 Other attempts were, however, soon made. In 1825, M. von Ungern- 

 Steruberg published his book On the Nature and Origin of Volca- 

 noes? in which, he says, his object is, to give an empirical representa- 

 tion of these phenomena. In the same year, Mr. Poulett Scrope pub- 

 lished a work in which he described the known facts of volcanic 

 action ; not, however, confining himself to description ; his purpose 

 being, as his title states, to consider " the probable causes of their 

 phenomena, the laws which determine their march, the disposition of 

 their products, and their connexion with the present state and past 

 history of the globe ; leading to the establishment of a new theory of 

 the earth." And in 1826, Dr. Daubeny, of Oxford, produced A De- 

 scription of Active and Extinct Volcanoes, including in the latter phrase 

 the volcanic rocks of central France, of the Rhine, of northern and 

 central Italy, and many other countries. Indeed, the near connexion 

 between the volcanic effects now going on, and those by which the 

 basaltic rocks of Auvergne and many other places had been produced, 

 was, by this time, no longer doubted by any ; and therefore the line 

 which here separates the study of existing causes from that of past 

 effects may seem to melt away. But yet it is manifest that the assump- 

 tion of an identity of scale and mechanism between volcanoes now 

 ictive, and the igneous catastrophes of which the products have sur 



1 Humboldt, Relation Historique : and his other works. 



" Vol. ii. Prop. 5. 



1 Werden imd Seyn dcs VulTcanischen Gebirges. Carlsruhe, 1825. 



