258 



COSMOS. 



siduity — partly from materials already published, and partly 

 from manuscript notes — upon the linear volcanoes of Cen- 



command of the Mexican viceroy, Matias de Galvez), by Jose Rossi y 

 Rubi (Alcalde Mayor de Guatemala, 1800), and by Joaquin Ysasi and 

 Antonio de la Cerda (Alcalde de Granada), which I possessed princi- 

 pally in manuscript. In the French translation of his work upon the 

 Canary Islands, Leopold von Buch has given a masterly extension of 

 my first sketch (Descr. Physique des Isles Canaries, 1836, p. 500-511) ; 

 but the uncertainty of geographical synonyms and the confusion of 

 names caused thereby gave rise to many doubts, which have been for 

 the most part removed by the fine maps of Baily and Saunders ; by 

 Molina's Bosquejo de la Republica de Costa Rica ; and by the great and 

 very meritorious work of Squier (Nicaragua, its People and Monuments, 

 with Tables of the Comparative Heights of 'the Mountains in Central Amer- 

 ica, 1852, vol. i., p. 418, and vol. ii., p. 102). The important work 

 which is promised us by Dr. Oerstedt, under the title of Schilderung 

 der Naturverhaltnisse von Nicaragua und Costa Rica, besides the ad- 

 mirable botanical and geological discoveries which constitute the pri- 

 mary object of the undertaking, will also throw fight upon the geog- 

 nostic nature of Central America. Dr. Oersted passed through that 

 region in various directions from 1816 to 1848, and brought back a 

 collection of rocks to Copenhagen. I am indebted to his friendly 

 communications for interesting corrections of my fragmentary work. 

 From a careful comparison of the materials with which I am acquaint- 

 ed, including those collected by Hesse, the Prussian consul-general in 

 Central America, which are of great value, I bring together the vol- 

 canoes of Central America in the following manner, proceeding from 

 south to north : 



Above the central plateau of Cartago (4648 feet), in the republic 

 of Costa Rica (lat. 10° 9), rise the three volcanoes of Turrialva, Irasu, 

 and Reventado, of which the first two are still ignited. 



Volcan de Turrialva* (height about 11,000 feet) is, according to 

 Oersted, only separated from the Irasu by a deep, narrow ravine. 

 Its summit, from which columns of smoke rise, has not yet been 

 ascended. 



The volcano Irasu,^ also called the volcano of Cartago (11,100 feet), 

 to the northeast of the volcano Reventado, is the principal vent 

 of volcanic activity in Costa Rica, but still remarkably accessible, 

 and toward the south divided into terraces in such a manner that 

 one may, on horseback, almost reach the elevated summit, from 

 which the two oceans, the sea of the Antilles and the Pacific, may 

 be seen at once. The cone of ashes and rapilli, which is about a 

 thousand feet in height, rises out of a wall of circumvallation (a 

 crater of elevation). In the flatter, northeastern part of the sum- 

 mit lies the true crater, of 7500 feet in circumference, which has 

 never emitted lava streams. Its eruptions of scoria? have often 

 (1723, 1726, 1821, 1817) been accompanied by destructive earth- 

 quakes, the effect of which has been felt from Nicaragua or Rivas 

 to Panama (Oersted). During a very recent ascent of the Irasu, 

 in the beginning of May, 1855, by Dr. Carl Hoffmann, the crater 

 of the summit and its eruptive orifices have been more accurate- 

 ly investigated. The altitude of the volcano is stated, from a 



