164 



the elevation of temperature in the stratum of 

 the air f which lies immediately over the sur- 

 face of the ocean. 



The road, which we were obliged to find across 

 the Malpays, was extremely fatiguing. The as- 

 cent is steep, and the blocks of lava rolled from 

 beneath our feet. I can compare this part of 

 the road only to the Moraine of the Alps, or 

 that mass of pebbly stones, which we find at the 

 lower extremity of the glaciers ; at the Peak, the 

 lava, broken into sharp pieces, leaves hollows, 

 in which we risked falling up to our waists. Un- 

 fortunately the laziness of our guides contribut- 

 ed to render this ascent more painful. Unlike 

 those of the valley of Chamouni, or the nimble 

 footed Guanches, who could, it is asserted, seize 

 the rabbit or wild goat in it's course, our Cana- 

 rian guides were models of the phlegmatic : they 

 wished to persuade us the preceding evening, 

 not to go beyond the station of the rocks : every 

 ten minutes they sat down to repose themselves, 

 and when unobserved threw away the specimens 

 of obsidian andpumicestone, which we had care- 

 fully collected. We discovered at length, that 

 none of them had ever yet visited the summit 

 of the volcano 



After three hours march, we reached, at the 

 extremity of the Malpays, a small plain, called 



* Biot : Rech. sur ies Refractions extraordinaires, p. 218, 223, 

 and 228. 



