242 COSMOS. 



numerous angular measurements, have also published a topo- 

 graphical sketch of its transverse valleys. 8 Pichiricha forms 

 a wall of black trachytic rock (composed of augite and oligo- 

 clase) more than nine miles in length, elevated upon a fissure 

 in the most western Cordilleras, near the South Sea, but 

 without the axis of the high mountain ridge coinciding in 

 direction with that of the Cordillera. Upon the ridge of 

 the wall, the three domes, set up like castles, follow from 

 S.W. to N.E. : Cuntur-guachana, Guagua-Pichincha (the 

 child of the old volcano) and el Picacho de los Ladrillos. 

 The true volcano is called the Father or the Old Man, Eucu- 

 Pichincha. It is the only part of the long mountain ridge 

 that reaches into the region of perpetual snow, and there- 

 fore rises to an elevation which exceeds the dome of Guagua- 

 Pichincha; the child, by about 190 feet. Three tower-like 

 rocks surround the oval crater, which lie somewhat to the 

 south-west, and therefore beyond the axial direction of a 

 wall which is on the average 15,406 feet in height. In the 

 spring of 1802, 1 reached the eastern rocky tower accompanied 

 only by the Indian, Felipe Aldas. We stood there upon the 

 extreme margin of the crater, about 2451 feet above the bot- 

 tom of the ignited chasm. Sebastian Wisse, to whom the phy- 

 sical sciences are indebted for so many interesting observations 

 during his long residence in Quito, had the courage to pass 

 several nights, in the year 1845, in a part of the crater where 

 the thermometer fell towards sunrise to 28. The crater is 

 divided into two portions by a rocky ridge, covered with 

 vitrified scoriae. The eastern portion lies more than a 

 thousand ieet deeper than the western, and is now the real 

 seat of volcanic activity. Here a cone of eruption rises to 

 a height of 266 feet. It is surrounded by more than seventy 

 ignited fumaroles, emitting sulphurous vapours. 9 From this 

 circular eastern crater, the cooler parts of which are now 

 covered with tufts of rushy grasses, and a Pourretia with 

 Bromelia-like leaves, it is probable that the eruptions of 

 fiery scoriae, pumice, and ashes of Rucu-Pichincha took 

 place in 1539, 1560, 1566, 1577, 1580, and 1660. The city 



8 Humboldt, Vuts de Cordilleres, p. 295, pi. Ixi, and Atlas dt la 

 Mat. Hist, du Voyage, pi. 27. 

 Kleinere Schriften, Bd. i, s. 61, 81, 83, and 88. 



