404 



COSMOS. 



chains of mountains, raised on transverse fiussres, and form- 

 ing mountain nodes. The range nearest to the shore is fre- 

 quently (but by no means always) the most active, while the 

 more distant, those more in the interior of the country, ap- 

 pear to be extinct or approaching extinction. It is some- 

 times thought that, in a particular direction in one and the 

 same range of volcanoes, an increase or diminution in the 

 frequency of the eruptions may be perceived, but the phenom- 

 ena of renewed activity after long intervals of rest render this 

 perception very uncertain. 



As many incorrect statements of the distance of volcanic 

 activity from the sea are circulated, either through ignorance 

 of, or inattention to, the exact localities both of the volcanoes 

 and of the nearest points of the coast, I shall here give the 

 following distances in geographical miles (each being equal 

 to about 2030 yards, or 60 to a degree) : In the Cordilleras 

 of Quito, the volcano of Sangay, which discharges uninter- 

 ruptedly, is situated in the most easterly direction, but its 

 distance from the sea is still 112 miles. Some very intelli- 

 gent monks attached to the mission of the Indios Andaquies, 

 at the Alto Putumayo, have assured me that on the upper 

 Rio de la Fragua,* a tributary of the Caqueta, to the east- 

 ward of the Ceja, they had seen smoke issue from a conical 

 mountain of no great height, and whose distance from the 

 coast must have been 160 miles. The Mexican volcano of 

 Jorullo, which was elevated above the surface in September, 

 1759, is 84 miles from the nearest point of the sea-shore (see 

 above, p. 296-303); the volcano of Pococatepetl is 132 

 miles ; an extinct volcano in the eastern Cordilleras of Bo- 

 livia, near S. Pedro de Cacha, in the vale of Yucay (see 

 above, p. 279), is upward of 180 miles; the volcanoes of 

 the Siebengebirge, near Bonn, and of the Eifel (see above, p. 

 221-227), are from 132 to 152 miles; those of Auvergne, 

 Velay, and Vivarais,! distributing them into thuee separate 



* The position of the Volcan de la Fragua, as reduced at Timana, 

 is N. lat. 1° 48', long. 75° 30' nearly. Compare the Carte Hypso- 

 metrique des Noeuds deMontagnes dans ks Cordilleres, in the large atlas 

 in my travels, 1831, pi. 5 ; see also pi. 22 and 24. This mountain ly- 

 ing isolated and so far to the east, ought to be visited by a geologist 

 capable of determining the longitude and latitude astronomically. 



t In these three gi'oups, which, according to the old geographical 

 nomenclature, belong to Auvergne, the Vivarais, and the Velay, the 

 distances given in the text are those of the northernmost parts of each 

 group as taken from the Mediterranean Sea (between the Golfe d'Aigues 

 Mortes and Cette). In the first group, that of the Puy de Dome, a 

 crater erupted in the granite near Manzat, called Le Gour de Tazena, 



