46 INTERNAL HEAT OF THE EARTH, 



difference in the two situations more than accidental? 

 A numerical determination depending on such inconsiderable 

 depths must be regarded as exceedingly uncertain, and the 

 increase of temperature may not always follow a uniform 

 law. Ought we to infer that if a gallery were to be driven 

 horizontally for many hundred fathoms from the lowest 

 depth of the Schergin Shaft, it would encounter everywhere, 

 and in every direction, frozen earth, and that with a tempe- 

 rature of 2-5 Cent, below 32? 



Schrenk has examined the ground-ice in 67i lat. in the 

 Samoied country, at Pustoienskoy Gorodok. In this case 

 the sinking of the well was aided by the application of fire. 

 In the middle of summer the frozen stratum was encountered 

 at a depth of little more than 5 feet ; it was followed through 

 a thickness of 67 feet, when the work was suddenly stopped. 

 The neighbouring lake of Ustie continued to be frozen over 

 and passable by sledges throughout the summer of 1813.( 48 ) 

 On my Siberian expedition with Ehrenberg and Gustav 

 Hose, we had a hole dug in the boggy or turfy soil near 

 Bogoslowzk (lat. 5 9 44') on the road to the Turjin Mine( 4 9) 

 in the Oural Mountains. At a depth of about 5J feet, we 

 came upon pieces of ice forming a kind of breccia with 

 frozen earth ; then solid ice, which continued to the depth 

 of 10 or 11 feet further, at which we left off. 



The geographical extent of the ground- or subterranean - 

 ice, i. e. the position and course of the southern limit, in 

 the old continent from Scandinavia to the eastern coast of 

 Asia, at which we begin to find in August, and throughout 

 the year, ice or frozen earth at a certain depth, is, according 

 to MiddendorfFs sagacious generalisations from observation, 

 like all other geothermic relations, often more <lq>en- 



