TRUE VOLCANOES. 253 



The volcano Cotopaxi:* 6 18,881 feet, according to Bouguer. 



The volcano Sahama* 7 (Bolivia) : 22,354 feet, according r,o Pentland, 



The volcano with which the fifth group ends is more than 



the summit of the volcano of Arequipa (trigonometrically) to be 

 11,031 feet, and the summit of Charcani 11,860 feet above the plateau 

 in which the town of Arequipa is situated. If now we fix the town of 

 Arequipa at 7841 feet, in accordance with the barometrical measurements 

 of Pentland and Rivero (Pentland, 7852 feet in the Table of Altitudes 

 to the Physical Geography of Mrs. Somerville, 3rd ed. vol. ii, p. 454; 

 Rivero, in the Memorial de Ciencias Naturales, t. ii, Lima, 1828, p. 65 ; 

 Meyen, Reise urn die Erde, Theil. ii, 1835, s. 5), Dolley's trigonometrical 

 operation will give for the volcano of Arequipa 18,881 feet (2952 toises), 

 and for the volcano Charcani,, 19,702 feet (3082 toises). But Pentland's 

 Table of Altitudes, above cited, gives for the volcano of Arequipa 

 20,320 English feet, 6190 metres (19,065 Paris feet), that is to say, 

 1945 feet more than the determination of 1830, and somewhat too iden- 

 tical with Hanke's trigonometrical measurement in the year 1796 ! In 

 opposition to this result the volcano is stated, in the Anales de la Uni- 

 versidad de Chile, 1852, p. 221, only at 5600 metres or 18,378 feet: con- 

 sequently 590 metres lower ! A sad condition of hypsometry ! 



46 Boussingault, accompanied by the talented Colonel Hall, has nearly 

 reached the summit of Cotopaxi. He attained, according to barome- 

 trical measurement, to an altitude of 5746 metres or 18,855 feet. There 

 was only a small space between him and the margin of the crater, but 

 the great looseness of the snow prevented his ascending further. Per- 

 haps Bouguer's statement of altitude is rather too small, as his compli- 

 cated trigonometrical calculation depends upon the hypothesis as to the 

 elevation of the city of Quito. 



47 The Sahama, which Pentland (Annuaire du Bureau des Longi- 

 tudes, 1830, p. 321) distinctly calls an active volcano, is situated, 

 according to his new map of the Vale of Titicaca (1848), to the east- 

 ward of Arica in the western Cordillera. It is 928 feet higher than 

 Chimborazo, and the relative height of the lowest Japanese volcano 

 Cosima to the Sahama is as 1 to 30. I have hesitated in placing the 

 Chilian Aconcagua, which, stated by Fitzroy in 1835 at 23.204 feet, 

 is, according to Pentland's correction, 23,911 feet, and according 

 to the most recent measurement (1845) of Captain Kellet of the 

 frigate Herald, 23,004 feet, in the fifth group, because from the 

 contradictory opinions of Miers ( Voyage to Chili, vol. i, p. 283) and 

 Charles Darwin (Journal of Researches into the Geology and Natural 

 History of the Various Countries -visited by the Beagle, 2nd ed. p. 291), 

 it remains doubtful whether this colossal mountain is a still ignited 

 volcano. Mrs. Somerville, Pentland, and Gilliss (Naval Attr. Exped. 

 vol. i, p. 126), also deny its activity. Darwin says : " I was surprised 

 at hearing that the Aconcagua was in action the same night (15th 

 January, 1835), because this mountain most rarely shows any sign of 

 action." 



