230 PHILOSOPHICAL TRANSACTIONS. [aNNO 1751. 



LVII. Observations made in going up the Peak ofTeneriffe. By Dr. Thomas 

 Heberden, and communicated by IVm. Heberden, M.D., F.R.S. p. 353. 



At 1 o'clock in the afternoon they set out from the villa or town of Orotava, 

 about 6 leagues distant from the peak of Teneriffe. The weather was cloudy ; 

 and before they had travelled quite a league, they found themselves surrounded 

 by a very thick mist or fog, which lasted about a league : all which time they 

 travelled among gardens and woods of pine-trees, after which they came to an 

 open country ; the soil very dry ; here and there a single pine-tree, and some 

 few Spanish broom-plants ; some loose stones, as large as a butt ; others, which 

 seemed to have been burned, and are supposed to be cast out from the volcano 

 of the peak. The sky very clear, and the thick mist, which they had passed 

 through, now seemed a sea of ash-coloured clouds below them. Having tra- 

 velled 1 leagues on this soil, they arrived at 8 o'clock in the evening at the Falda 

 del Pico, or foot of the peak. Here they we;-e obliged to leave their horses ; the 

 road, by reason of its steepness and loose sandy soil, being impassable to them. 

 At half a league's distance they baited under some large rocks, called La Estancia 

 de los Ingleses, or the English baiting-place, being first used as such by some of 

 our countrymen in ascending the peak. Here they rested all night, making 

 fires to temper the air, which they found very cold. When the morning drew 

 near, they proceeded on their journey, ascending for a quarter of a leao-ue the 

 same soil (but more steep and loose) till they arrived at some large rocks of mal- 

 payses (or stone burnt by a volcano) ; among which, as the ground was more 

 firm, they walked with less trouble, or rather climbed, being frequently obliged 

 to make use of their hands to help them forward. Having gone about a quarter 

 of a league in this manner, they arrived at the famous cave of Teyde. It is sur- 

 rounded on all sides (or rather buried) with large mal-payses, orvolcanian rocks, 

 between which you discover the entrance about 6 feet high, and 4 feet wide. 

 The cave seems to be about 15 feet wide at the entrance; the extremity they 

 could not discover. From its entrance to the surface of the water, which covers 

 the bottom, seems to be about 12 or 14 feet. The top and sides of the cave are 

 of smooth stone. The bottom is covered with ice or snow ; above which is a 

 body of water about half a yard deep. This cave is the grand reservoir of snow 

 of the island, whence they are supplied, when their common reservoirs, which 

 they prepare for cooling their liquors, fail them. 



At somewhat more than a quarter of a league's distance from the cave, they 

 came to a plain of sand ; from the middle of which arises a yellowish pyramid of 

 sand or cinders, which the inhabitants call La Pericosa, and we the Sugar-loaf; 

 around the base of which perspire vapours incessantly. The sugar-loaf is about 

 an 8th part of a league to the top, which \%. very difficult of ascent, occasioned 



