484 



Subsurface Geologic Methods 



TIE CABLE TO GIRT 



RECORDING GAUGE 



,KELLY 



instrumentT" 



PANEL /*- . 



DERRICK FLOOR 



-COPPER TUBING 



Figure 228. Martin-Decker, rate-of-penetration recorder. 



directly responsible for the proper decisions that must be made during 

 the drilling operation (figs. 224 and 225). 



In addition to the foot-by-foot drilling-time record, a meter is pro- 

 vided which shows the total depth at all times, which thus provides for 

 a continuous check on the pipe tally, and which eliminates many errors 

 in depth. 



The front of the unit is provided with a dial on which an indicator 

 revolves so that the driller can tell to the inch where he is on any particu- 

 lar foot of hole. 



Parallel to and contemporaneous with the drilling-time column of the 

 "Geolograph" chart, a second pen records the down time. When the bit 

 is raised off bottom, this pen moves to the right, automatically marking 



