Sir J. Herschei on the Phenomena of the Freezing Cave. 859 



peculiar condition of the cavern during the hottest summer months. 

 He states also that he particularly urged the authorities at Oren- 

 burg as well as the directors of the Salines to keep accurate regis- 

 ters of the temperature throughout the year, and to ascertain pre- 

 cisely the changes which the cave undergoes between the extremes 

 of summer and winter. There is, he observes, a very marked dif- 

 ference between the climate of the steppes south of Orenburg and 

 that of Ekaterinburg, not merely due to the difference of six de- 

 grees of latitude, but arising also from the altitude of the position 

 of Ekaterinburg and the shortness of its varying summers as well 

 as from the long droughty summers of the steppes, which are re- 

 moved from all mountain chains, and possess comparatively no great 

 altitude above the sea. In the southern region, he conceives, a sub- 

 stratum of frozen matter cannot exist, there being a most extraor- 

 dinary difference between the climate of Yakatsk (lat. 62|° N. long. 

 131° E.) and that of Orenburg (lat. 51° 46' N.), the winter of the 

 former lasting eight or nine months, with the thermometer during long 

 periods constantly 30° and sometimes 40° of Reaumur below zero*. 



Respecting the explanation that the difference of temperature in 

 the cave is due to the propagation through the gypsum hillock of 

 the heat or cold of the preceding summer or winter season, Mr. 

 Murchison conceives that the fissures which ramify from the cave 

 into the hill, present difficulties to such a solution. When he was 

 on the spot, the existence of these fissures led him to speculate upon 

 the possibility of the phenomena being due to currents of air' 

 passing over subterranean floors of moistened rock-salt, and on the 

 effects which would be produced when such currents came in contact 

 with a stream of dry heated air. 



LXV II. Extractsfrom a letter addressed by Sir J. Herschel, 

 Bart. 9 F.G.S., to Mr. Murchison, explanatory of the Phe- 

 nomena of the Freezing Cave of Illetzkaya Zatchitaf. 



"HPHAT the cold in ice-caves (several of which are alluded to in a 

 ■■- part of this letter not published) does not arise from evaporation, 

 is, I think, too obvious to need insisting on. It is equally impos- 

 sible that it can arise from condensation of vapour, which produces 

 heat, not cold. » When the cold (by contrast with the external air, 



* Mr. Murchison ascertained during his journey in the North of Russia 

 in 1840, that much remains to be done relative to the circumstances of the 

 recorded frozen substratum at Yakatsk ; and he states the following as points 

 requiring attention. 1st. With the exception of about sixty feet of alluvial 

 soil, the whole shaft to a depth of 350 feet was sunk through solid strata 

 of limestone two to six feet thick, and shale with a little coal ; 2ndly, That 

 none of the sinkings took place in summer although renewed for several 

 years, on account of the foul air generated in the shaft ; 3rdly, That when 

 Admiral Wrangel descended the shaft during the summer, and the surface 

 was burnt up, he found the thermometer to stand at 6° Reaum. below zero. 



f From the Proceedings of the Geological Society, vol. ii. part 2; having 

 been read March 9, 1842. 



