Humboldt remarks, that the mean temperature of the region in which the Cueva del Hielo (ice-cave) occurs, is not below 3° C. (37.4° F.), but so much snow and ice are stored up in the winter that the utmost efforts of the summer heat cannot melt it all. He adds, that the existence of permanent snow in holes or caves must depend more upon the amount of winter snow, and the freedom from hot winds, than on the absolute elevation of the locality. The natives of Teneriffe are men of faith. They have large belief in the existence and intercommunication of numerous vast caverns in the Peak, one of which, on the north coast, is said to communicate with the ice-cavern, notwithstanding 8 miles of horizontal distance, and 11,000 feet of vertical depth. The truth of this particular article of their creed has been recently tested by several worthy and reverend hidalgos, who drove a dog into the entrance of the cavern on the sea-coast, in the belief that he would eventually come to light again in the ice-cave: he was accordingly found lying there some days after, greatly fatigued and emaciated, having in the interval accomplished the 11,000 feet of subterranean climbing. How he could enter, from below, a water-logged cave, does not appear to have been explained. FOOTNOTES: [Footnote 98: The _Caves of Szelicze_ are mentioned in Murray's _Handbook of Southern Germany_ (1858, p. 555), where the following account is given of them:--'During the winter a great quantity of ice accumulates in these caves, which is not entirely melted before the commencement of the ensuing winter. In the summer months they are consequently filled with vast masses of ice broken up into a thousand fantastic forms, and presenting by their lucidity a singular contrast to the sombre vaults and massive stalactites of the cavern.' The _Drachenhöhle_ (Murray, 1. c.p. 553), a series of caverns not far from Neusohl in Hungary, afford another instance of an ice-cave, one of the largest of them being said to be coated with a sheet of translucid ice, through which the stalactitic fretwork of the vault is seen to great advantage.] [Footnote 99: Not far from Kaschau.] [Footnote 100: _Travels in Hungary_, 1797, pp. 317, &c.] [Footnote 101: _A Peep into Toorkistan_; London, 1846; chapters x. and xi.] [Footnote 102: They were now in a country far removed from the Affghans, and hostile to that people.] [Footnote 103: The remainder of this paragraph is in Captain Burslem's own words.] [Footnote 104: I am indebted for the knowledge of the existence of these caves to W.A. Sandford, Esq., F.G.S., who informed me that an account of them was to be found in a book of travels by an English officer. I am not aware that they have been visited on any other occasion than this.] [Footnote 105: _Reise durch Island_, Copenhagen, 1744 (being a German translation from the original Danish), i. 128 sqq.] [Footnote 106: _Henderson's Iceland_, ii. 189 sqq.] [Footnote 107: Pp. 145 sqq.]