ON ITS EXTERIOR. VOLCANOES. 229 



Quito from north to south. The seat of volcanic action ex- 

 tends under the whole of that elevated province ; ( 227 ) its 

 several channels of communication with the atmosphere being 

 the volcanic mountains of Pichincha, Cotopaxi, and Tungu- 

 ragua, which, by their grouping, as well as by their lofty 

 elevation and grand outlines, present the most sublime and 

 picturesque aspect which is anywhere concentrated within 

 BO small a space in a volcanic landscape. The extremities 

 of volcanic chains are connected with each other by sub- 

 terranean communications ; and this fact, which experience 

 has made known to us in numerous instances, reminds us of 

 the old and just statement of Seneca, that (t the crater is 

 only the issue of the deeper seated volcanic forces." ( 228 ) 

 The Mexican volcanoes of Orizaba, Popocatepetl, Jorullo, 

 and Colima, also appear to be connected with each other, 

 and are situated over a transverse fissure running from sea 

 to sea. As was first shewn by myself, ( 229 ) these moun- 

 tains are all situated between 18 59' and 19 12' of North 

 latitude; and in the exact line of the direction of these 

 volcanoes, and over the same transverse fissure, Jorullo 

 was suddenly elevated on the 29th of September, 1759 ; 

 this last mountain has only once sent forth streams of 

 lava, resembling in this respect Mount Epomeo in the 

 island of Ischia, of which likewise only a single eruption (in 

 1302) is recorded. 



But although Jorullo, situated eighty miles from any 

 active volcano, is in the strictest sense a " new moun- 

 tain," yet its appearance must not be confounded with 

 that of the Monte Nuovo near Pozzuolo (19th Sep- 

 tember, 1538), which is rather to be classed with the 

 " craters of elevation." It appears, indeed, to me, to agree 

 better with the results of observation, if we compare the sudden 



