298 REACTION OF THE INTERIOR OF THE EARTH 



mony of the Indians in the neighbourhood, had taken 

 place in the last twenty years, I found the temperature in 

 the cracks of the hornitos generally between 199-4 and 

 203 ; and standing at a distance of fully twenty feet 

 from some of the hills, where not touched by any 

 vapours, the temperature of the air was still 108*5 and 

 116*2, when the proper temperature of the playas at the 

 same hour was barely 77. The weak sulphuric vapours 

 discoloured test-paper, and for some hours after sunrise 

 were seen to rise to a height of from 60 to 64 feet. The 

 view of the columns of smoke was most striking in the 

 cool of the early morning. Towards noon, and even at 

 11 A.M., they had sunk so low as only to be visible when 

 quite near. In the interior of several of the hornitos, 

 we heard a sound like the fall or rush of water. As 

 already remarked, they possessed little solidity, and 

 when Burkart visited the Malpais, twenty-four years 

 after me, he found none sending forth smoke, the 

 temperature of most of them was no higher than that 

 of the surrounding air, and in many all regularity of 

 shape had been obliterated by the effects of rain, &c. 

 Burkart found near the principal volcano small cones of 

 a brownish-red conglomerate composed of very loosely 

 connected rounded or angular pieces of lava. There is 

 still seen, in the midst of the area covered by the 

 hornitos, the remains of a former rising ground, running 

 east and west, and drawn on my map, on which the 

 farm-buildings of San Pedro had rested ; its preserva- 

 tion at the foot of the great volcano excites astonishment. 

 Part of it only is covered with volcanic sand (or burnt 

 rapilli). The projecting basaltic rock, overgrown with 

 aged trunks of Ficus indica and Psidium, is assuredly, as 



