CAVERNS. 251 



the earth, and light a quickly blazing fire over it, when the desired coolness is produced. 

 On the contrary, the more the warmth and dryness of the external air are diminished, 

 as in winter, the less will be its capability to promote evaporation in the cavern, the 

 warmth contained in the air will no longer be absorbed, and the ice which has been 

 produced must melt. The cooling in these caverns, however, so as to sink below the 

 freezing point, can only occur where there is a certain relation, which but rarely subsists, 

 between the openings and the evaporating surface of the interior. If the opening is too 

 large, too much warm air is introduced, and the temperature of the interior is thereby 

 much more increased than it can be diminished by evaporation. If it is too small, the 

 vapours cannot withdraw themselves fast enough, and the evaporation is lessened, because 

 the surrounding air is saturated with moisture. The ice-caverns, therefore, are com- 

 paratively rare ; but, in addition to those named, there is a cave at Vesoul, in France, 

 where a stream flowing through it is frozen over in summer, and clear of ice in winter. 

 Mr. Murchison, in the course of some recent geological surveys in Russia, met with a 

 freezing cavern near the imperial salt-works at Iletski, to the south of the Ural 

 mountains, situated at the southern base of a hillock of gypsum, one of a series of 

 natural hollows used by the peasantry for cellars or stores. The cave in question is 

 however the only one in the district which possesses the singular property of being 

 partially filled with ice in summer, and of being destitute of it in winter. " Standing on 

 the heated ground and under a broiling sun, I shall never forget," he remarks, " my 

 astonishment when the woman to whom the cavern belonged unlocked a frail door, and a 

 volume of air so piercingly keen struck the legs and feet, that we were glad to rush into 

 a cold bath in front of us to equalise the effect." Three or four feet within the door, and 

 on a level with the village street, beer and quash were half frozen. A little further the 

 narrow chasm opened into a vault fifteen feet high, ten paces long, and from seven to 

 eight feet wide, which seemed to send off irregular fissures into the body of the hillock. 

 The whole of the roof and sides were hung with solid undripping icicles, and the floor 

 was covered with hard snow, ice, or frozen earth. During the winter all these 

 phenomena disappear ; and when the external air is very cold, and all the country is 

 frozen up, the temperature of the cave is such, that the Russians state they could sleep 

 in it without their sheep -skins. 



There is another circumstance of high interest disclosed by the interior of many 

 caverns, the occurrence of extinct animals of the ancient earth ; on which account these 

 receptacles have obtained the name of zoolithes or bone caverns. This phenomenon 

 prevails in almost every country of Europe, and also of America, and has obtained of 

 late years, particularly by the investigations of Dr. Buckland, who has made it the 

 subject of his peculiar study, a high degree of importance, on account of the light which 

 it throws upon the ancient condition of the earth, and the changes which the surface has 

 undergone. His researches into the condition of a cave discovered in 1821 at Kirkdale 

 in Yorkshire are highly valuable, and deserve a notice here. Its mouth had long been 

 choked up with rubbish, and overgrown with grass and bushes, but was accidentally 

 found by some workmen. The cave is situated on the older portion of the oolite forma- 

 tion (in the coral rag and Oxford clay) on the declivity of a valley. It extends as an 

 irregular narrow passage 250 feet into the hill. There are a few expansions, but scarcely 

 high enough to allow a man to stand upright. The sides and floor were found covered 

 with a deposit of stalagmite, beneath which there was a bed of from two to three feet of 

 fine sandy and micaceous loam, the lower portion of which in particular contained an 

 innumerable quantity of bones, with which the floor was completely strewn. The 

 greatest part of them were very well preserved, and still retained a great portion of their 

 natural gluten, in consequence of the peculiar nature of their investiture. The animals 



