THE FROZEN SOIL. 49 



gently throughout the whole year, in the most northern 

 parts of the Scandinavian peninsula, as far east as the coasts 

 of Asia, depends, according to MiddendorfF's acute observa- 

 tions (like all geothermal relations), more upon local influ- 

 ences than upon the temperature of the atmosphere. The 

 influence of the latter is, on the whole, no doubt, stronger 

 than any other ; but the isogeothermal lines are not, as Kupf- 

 fer has remarked, parallel in their convex and concave curves 

 to climatic isothermal lines, which are determined by the 

 means of the atmospheric temperature. The infiltration of 

 liquid vapors deposited by the air, the rising of thermal 

 springs from a depth, and the varying conductive powers of 

 the soil, appear to be especially active.* " On the most 

 northern point of the European continent, in Finmark, be- 

 tween the high latitudes of 70° and 71°, there is as yet 

 no continuous tract of frozen soil. To the eastward, im- 

 pinging upon the valley of the Obi, 5° south of the North 

 Cape, we find frozen ground at Obdorsk and Beresow. To 

 the east and southeast of this point the cold of the soil in- 

 creases, excepting at Tobolsk, on the Irtisch, where the tem- 

 perature of the soil is colder than at Witimsk, in the valley 

 of the Lena, which lies 1° farther north. Turuchansk (Q5° 54z / 

 N. lat.) on the Jenisei, is situated upon an unfrozen soil, al- 

 though it is close to the limits of the ice. The soil at Am- 

 ginsk, southeast of Jakutsk, presents as low a temperature 

 as that of Obdorsk, which lies 5° farther north ; the same 

 being the case with Oleminsk, on the Jenisei. From the 

 Obi to the latter river the curve formed by the limits of the 

 frozen soil seems to rise a couple of degrees farther north, 

 after which it intersects, as it turns southward, the Lena 

 valley, almost 8° south of the Jenisei. Farther eastward, 

 this line again rises in a northerly direction."! Kupffer, 

 who has visited the mines of Nertshinsk, draws attention to 

 the fact that, independently of the continuous northern mass 



* Compare my friend G. von Helmersen's experiments on the rela- 

 tive conductive powers of different kinds of rocks (Mem. ch V Academic 

 cle St. Peter sbourg : Melanges Physiques et Chimiques, 1851, p. 32). 



f Middendorff, bd. i., s. 166. Compare also s. 179. " The curve 

 representing the commencement of the freezing of the soil in North- 

 ern Asia exhibits two convexities, inclining southward, one on the 

 Obi, which is very inconsiderable, and the other on the Lena, which 

 is much more strongly marked. The limit of the frozen soil passes 

 from Berresow, on the Obi, toward Turuchansk, on the Jenisei; it 

 then runs between Witimsk and Oleminsk, on the right bank of the 

 Lena, and, ascending northward, turns to the east." 



Vol. V.— C 



