209 



the experiments I made on the difficulties arising 

 from the declivities in mountainous countries. 



Isolated volcanoes, in the most distant re- 

 gions, are very analogous in their structure. 

 At great elevations all have considerable plains, 

 in the middle of which arises a cone perfectly 

 circular. Thus at Cotopaxi the plains of Suni- 

 guaicu extend beyond the farm of Pansache. 

 The stony summit of Antisana, covered with 

 eternal snow, forms an islet in the midst of an 

 immense plain, the surface of which is twelve 

 leagues square, while it's height exceeds that of 

 the Peak of TenerifFe two hundred toises. At 

 Vesuvius, at three hundred and seventy toises 

 high, the cone detaches itself from the plain of 

 Atrio del Cavallo. The Peak of TenerifFe pre- 

 sents two of these elevated plains, the uppermost 

 of which, at the foot of the Pi ton, is as high as 

 Etna, and of very little extent ; while the lower- 

 most, covered with tufts of retama (spartium 

 nubigenum), reaches as far as the Estanciade 

 los Ingleses. This rises above the level of the 

 sea, almost as high as the city of Quito, and the 

 summit of Mount Lebanon. 



The greater the quantity of matter that has 

 issued from the crater of a mountain, the more 

 elevated is it's cone of ashes in proportion to the 

 perpendicular height of the volcano itself. No- 

 thing is more striking under this point of view, 

 than the difference of structure between Vesu- 



vol. i, p 



