Miscellaneous Subsurface Methods 595 



and a picture is taken. The dot made on the disc by the point of light from 

 the plumb bob indicates the low side of the hole. Thus, the position of one 

 of the magnets in azimuth in respect to the low side of the hole can be 

 ascertained. After the core barrel has been removed from the well bore, a 

 line is extended optically from the magnet along the core barrel to the 



f? 



Figure 309. Oil-well cores. 



edge of the core. A mark made at this point on the core is used as a 

 basis for orientation. It will be noted that no scriber need be used in this 

 method. 



The "Corex" equipment is illustrated in C of figure 306. This method 

 IS applicable only to cores taken with wire-line retractable coring equip- 



