14 



PRINCIPLES OF STRATIGRAPHY 



in 



1,273 meters (3,492 feet), showed a rate of increase of 1° F 

 51.5 feet depth ; the bore at Schladebach, Saxony (west of Leipzig), 

 extending to a depth of 1,748 meters (5,630 feet), showed a rate of 

 increase of 1° F. in 67.1 feet, while the Calumet and liecla mine 



/^O /)7//es or z^ 



HEIGHT OFflTm05PHERE 

 100 miles. 



5>° 



'I -5 



Sea Level 



■M^ 



'Fig. 4. 



Diagram illustrating the relation of the superficial features of the 

 earth to the entire mass. Scale i inch = 53 1-3 miles. Drawn 

 to radius of 75 inches (=4,000 miles). 



of Northern Michigan, with a depth of 4,939 feet, showed a rate of 

 increase of 1° F. in 103 feet depth, though between 3,324 feet and 

 4.837 feet the rate of increase was as high as 1° F. in 93.4 feet. 

 Other bores and mines show intermediate values.* In the Witwa- 



* The deepest well yet completed is at Paruschowitz, Province of Silesia, 

 which reached a depth of 2,003 meters (6,571.5 feet). 



