PHOTOGRAPHIC METHODS 203 



with this instrument have been pubUshed,^ while Fig. 

 142 shows the course of the first 6,948 ft. of the deepest 

 well as surveyed by this device. Goodrich^ quotes an 

 instance of one survey by this device in a well 6,522 ft. 

 deep taking 6 hr. 45 min. 



1 Smith, F. M., Oil Gas Jour., p. 120, Dec. 2, 1926; Eng. Min. Jour. 

 Press, Feb. 6, 1926; Anderson, A., Oil Age, p. 20, September, 1926. 



2 Oil Gas Jour., p. 38, Nov. 15, 1928. 



