The refraction seismograph in use. Harry Hancock, Senior Geophysicist, (see AAS Review #2) records time readings on the MD-1 as Mike Wood (borrowed from aicrew where he navigates on photo-survey) swings the hammer. When he strikes the plate, a switch on the hammer handle closes, starting the MD-1. Lights flash on the panel marking the milliseconds elapsed between origin of seismic wave, at point of hammer blow, and reception at geophone. The wave stops the flashing, and lights left on indicate the time interval. For more information see the back page of How Adastra Can Serve You brochure.

Photo: Patricia Jones (PJ-001)