258 REACTION OF THE INTERIOR OF THE EARTH 



eruptions were combined with the greatest noise, the 

 sound was heard distinctly, not merely in the harbour 

 of Gruayaquil, but also farther to the south, along the 

 shores of the Pacific, as far as Payta and San Buena- 

 ventura ; a distance about equal to that between Berlin 

 and Basle, the Pyrenees and Fontainebleau, or London 

 and Aberdeen. Although, since the beginning of the 

 present century, the volcanoes of Mexico, New Granada, 

 Quito, Bolivia, and Chili have been visited by geologists, 

 yet, unfortunately, Sangay (which exceeds Tungurahua 

 in height), owing to its solitary position remote from all 

 routes of communication, has remained entirely neg- 

 lected. It was not until December 1849, that an adven- 

 turous and highly informed traveller, Sebastian Wisse, 

 who had resided five years among the Andes, ascended 

 Sangay and almost reached the highest summit of the 

 steep snow-covered cone ; he determined chronome- 

 trically the exact intervals *of the astonishingly fre- 

 quent eruptions, and examined the composition of 

 the trachyte which, limited to so restricted an area, 

 breaks through the gneisp ; 267 eruptions were counted 

 in an hour, each lasting on an average 13 "'4, ( 384 ) 

 and which is very remarkable not accompanied 

 by any sensible shaking of the cone of cinders. The 

 erupted substances, veiled for the most part in much 

 smoke (sometimes of a grey, and sometimes approaching 

 to an orange colour), consisted chiefly of mingled black 

 ashes and rapilli, but partly also of scoriae, which 

 rose perpendicularly and were globular, about 16 

 or 17 inches in diameter. In one of the strongest 

 eruptions, Wisse counted from 50 to 60 glowing stones 

 simultaneously erupted. Most of them fall back into 

 the crater ; sometimes they cover its upper margin, or 



