Figure 9. Geospace GT-2A Portable Refraction Recorder. Records are 

 made on type 47 Polaroid film in camera at center. Knobs 

 on upper half of panel control the amplifier pots; OPERATE, 

 TEST, and SAFETY switches are closest to the operator. 

 Recorder is wired for cap detonation (lower left) and 

 connected to the jumper cable (right side). 



