44 COSMOS. 



Here a subterranean stratum of ice was pierced to a depth 

 of more than 382 feet. The thermometer was sunk at 

 eleven points along the lateral walls of the shaft between 

 the surface and the greatest depth, which was reached in 

 1837. The observer was obliged to be let down standing in 

 a bucket, with one arm fastened to a rope, while he read off 

 the thermometric scale. The series of observations, whose 

 mean error does not amount to more than 0. 45 F. embrace 

 the interval between April 1844 and June 1846. The 

 decrease of cold was not proportional to the depth at indi- 

 vidual points, but nevertheless the following results were 

 obtained for the total increase of the mean temperatures for 

 the different superimposed frozen strata : 



50 feet - - 17.13F. 



100 - - 20.26 



150 21.43 



200 23.27 



250 24.49 



382 26.60 



After a very careful consideration of all these observations, 

 Middendorff determined the general increase of tempera- 

 ture to be 1 F. for eveiy space varying from 44.5 to 52 

 feet. 46 This result shows a more rapid increase of heat in 



to continue the boring ; and, up to 1837, although an opening had 

 been made to a depth of 382 feet below the surface, it had not pene- 

 trated beyond the ice. 



46 Middendorff, Reise in Sib. Bd. i, s. 125 133. "If we exclude," 

 says Middendorff, "those depths which did not quite reach 100 feet, 

 on the ground that they were influenced by annual deviations of tem- 

 perature, as was determined by experiments previously made in Siberia, 

 we shall still find certain anomalies in the partial increase of heat. 

 Thus, for instance, between the depths of 150 200 feet the tempera- 

 ture rises at a ratio of 1 F. for only 29.3 feet, while between 250 

 300 feet the corresponding increase is 96.4 feet. We may, therefore, 

 venture to assert that the results of observations that have hitherto 

 been obtained in Shergin's shaft are by no means sufficient to deter- 

 mine with certainty the amount of the increase of temperature, and 

 that, notwithstanding the great variations which may depend upon the 

 different conductive powers of the terrestrial strata, and the disturbing 

 influence of the air or water which enters from above, an increase of 

 1 F. occurs for every 44 52 feet. The result of 52 feet is the mean of 

 BI'X partial increases of temperature, measured at intervals of 50 feet 

 between the depths of 100 and 882 feet. On comparing the mean 



