Keep railroad lights and signs lit and signaling properly.
Obtains sample of earth formations in sidewalls of oil well boreholes, using electrically exploding device: Loads explosives into gun chambers of tubular firing device. Connects gun chambers to electric detonating cable, using handtools. Signals HOIST OPERATOR to lower sample-taking gun into well. Observes wire line measuring device, weight indicator, and instrument panel of control equipment in truck to position sample-taking gun at specified point in well. Moves controls to set off electrical igniters that fire cylinders into sidewall of rock formation to obtain sample of earth. Signals HOIST OPERATOR to raise equipment and sample from well. May be required to have license for handling explosives. May operate hoist to lower and raise tools and equipment from well.