CANARY ISLANDS. 41 



of the crater. We immediately prepared for observation, 

 and with some difficuUy, struck up a fire on the leeward 

 side near the top of the highest pinnacle. 



Observations. — Temperature of the atmosphere on the 

 top of the Peak, 7'2^ ; at six feet above, 39° ; temperature 

 of boiling hot-water, 190o. On thrusting a lance into the 

 crater to the depth of a foot, and introducing the ther- 

 mometer, the mercury instantaneously rose to 220°, the 

 extent of its graduation. The plate of the instrument 

 accumulated, from the vapor which issued from the aper- 

 ture, some drops of liquid that had a powerful corroding 

 effect. It is highly probable that these vapors contain 

 muriatic or sulphuric acid ; or the corrosion of the plate of 

 the instrument was caused by sulphuretted hydrogen com- 

 ing in contact with it. Sound was greatly diminished 

 when made with the same efforts as below ; the compass was 

 not at all agitated. From the disagreeable and nauseous 

 effect of the sulphureous exhalations of the volcano, and 

 the difficulty of breathing, we were under the necessity of 

 suspending further observation, and descended, as soon as 

 practicable, to La Cueva del Yelo, where we stopped 

 and refreshed ourselves, took hs dimensions, and the 

 temperature of the water which it contained. It is entered 

 by an irregular aperture of about eight feet in diameter, 

 and is fifteen feet deep, twenty-five wide, and as far as 

 penetrated, two hundred feet in length. Its bottom is a 

 solid bed of ice covered with pure crystalline water about 

 a foot deep, having a temperature of 41°. During winter, 

 this cavern is filled with ice and snow ; and as the rays of 

 the sun do not penetrate beyond its mouth, the heats of 

 summer are insufficient to empty the reservoir. There is 

 a tradition amongst the natives here, that the v.-ater in this 

 cave was formerly unfathomable, and that it ebbed and 

 flowed with the sea. 



At mid-day, we returned to La Estancia, where we over- 

 took our other companions. Overpowered with fatigue, 

 and affected with an unaccountable perturbation of mind, 

 I was unable to proceed any further without relief. The 

 cause of my illness was soon discovered, and alter being 

 removed, we continued our descent over Las Canadas, and 

 4* 



