THE TEMPERATURE OF THE EARTH. 47 



in Schergin's shaft than has been obtained from different 

 borings in Central Europe, whose results approximate closely 

 to one another (see p. 39). The difference fluctuates be- 

 tween ^th and ^th. The mean annual temperature of Ja- 

 kutsk was determined at 13°*7 F. The oscillation between 

 the summer and winter temperature is so great, according to 

 Newerow's observations, which were continued for fifteen 

 years (from 1829 to 1844), that sometimes for fourteen days 

 consecutively, in July and August, the atmospheric tempera- 

 ture rises as high as 77°, or even 84° -6 F. ; while during 120 

 consecutive winter days, from November to February, the 

 cold falls to between — 42°-3 F. and —69° F. In estimat- 

 ing the increase of temperature which was found on boring 

 through the frozen soil, we must take into account the depth 

 below the surface at which the ice exhibits the temperature 

 of 32° F., and which is consequently the nearest to the lower 

 limit of the frozen soil ; according to Middendorff 's results, 

 which entirely agree with those that had been obtained much 

 earlier by Erman, this point was found in Schergin's shaft to 

 be 652, or 684 feet below the surface. It would appear, 

 however, from the increase of temperature which was ob- 



this increase. From the acute investigations of Middendoiff and 

 Peters, in reference to the velocity of transmission of changes of at- 

 mospheric temperature, including the maxima of cold and heat (Mid- 

 dend., s. 133-157, 168-175), it follows that in the different borings, 

 which do not exceed the inconsiderable depth of from 8 to 20 feet, 

 " the temperature rises from March to October, and falls from Novem- 

 ber to April, because the spring and autumn are the seasons of the 

 year in which the changes of atmospheric temperature are most con- 

 siderable" (s. 142-145). Even carefully covered mines in Northern 

 Siberia become gradually cooled, in consequence of the walls of the 

 shafts having been for years in contact with the air ; this cause, how- 

 ever, has only made the temperature fall about 1° F. in Schergin's 

 shaft, in the course of eighteen years. A remarkable and hitherto un- 

 expITlined phenomenon, which has also presented itself in the Scher- 

 gin shaft, is the warmth occasionally observed in the winter, although 

 only at the lowest strata, without any appreciable influence from with- 

 out (s. 156-178). It seems still more striking to me, that in the bor- 

 ings at Wedensk, on the Pasina, when the atmospheric temperature 

 is —31° F., it should be 26°'-4 at the inconsiderable depth of 5 or 10 

 feet ! The isogeothermal lines, whose direction was first pointed out 

 by KupflPer in his admirable investigations (Cosmos, vol. i., p. 219), will 

 long continue to present problems that we are unable to solve. The 

 solution of these problems is more especially difficult in those cases 

 in which the complete perforation of the frozen soil is a work of con- 

 siderable time ; we can, however, no longer regard the frozen soil at 

 Jakutsk as a merely local phenomenon, which, in accordance with 

 Slobin's view, is produced by the terrestrial strata deposited from wa- 

 ter (Middend., s. 167). 



