128 



HEAT OF EARTH S OUTER CEUST. 



The following sets of observations, of which the 

 first was made in mid- winter, the second in the 

 middle of summer, are borrowed from a very ex- 

 tensive series made by G. Bischof. 





Thermometric Degrees observed on 



Depth in 



Parisian 



feet. 



July ,18, 



1836. 



January 21, 1837. 



Centigrade. 



Fahrenheit. 



Centigrade. 



Fahrenheit. 



6 



16-12 



60-99 



4-81 



40-75 



12 



12-06 



53-6 



7-81 



46 



18 



10 



50 



9-94 



49-9 



24 



95 



49 



10-95 



51-79 



30 



9-62 



49-1 



10-88 



51-58 



36 



10*2 



50-5 



10-88 



51-58 



According to these results, the influence of the 

 summer-heat is not felt, at a depth of 30 feet, 

 before the winter of the following year, nor the 

 influence of the winter-cold before the next sum- 

 mer. 



Bischof found the mean temperature of the 

 year, at Bonn, to be as below : — 







Thermometric 



Degrees. 



Depth in 



Annual Mean 



Difference between Highest 



Parisian 

 feet. 







and Lowest Temperatures. 



Centigrade. 



Fahrenheit. 



Centigrade. 



Fahrenheit. 



6 



9-7 



49-3 



12-38 



22-38 



12 



9-8 



49-5 



8-13 



14-63 



18 



10 



50 



4-88 



8-78 



24 



10-2 



50-5 



2-75 



495 



30 



10-4 



50-7 



144 



2-59 



36 



10-6 



51 



0-81 



1-45 



