668 Subsurface Geologic Methods 



against the formation in wells up to twelve inches in diameter. By remov- 

 ing the springs the camera, which is 4^^ inches in diameter, can be used 

 in a hole as small as 4| inches in diameter. 



For comparison it might be noted here that the camera model pre- 

 ceding the one described above used an Argus model AF 35-millimeter 



Figure 356. Bell and Howell 16-millimeter camera fitted with a 

 solenoid release for use as a deep-well camera. 



camera with electric-motor drive requiring a case with an outside diameter 

 of six inches. Use of this camera was limited to large-diameter wells. A 

 further handicap was the fact that only 36 exposures could be made with- 

 out reloading. 



When a well is to be photographed, it is first necessary to determine 

 the type of fluid covering the section of formation where the pictures 



