Library Digital Collections

Technician William J. Brennan, aboard the D/V Glomar Challenger (ship) helped place a new air gun into the water for a check before beginning Leg 51 of the Deep Sea Drilling Project in the harbor of San Juan, Puerto Rico. The air gun, which was a larger version of the bolt equipment the ship had used since 1968, was towed approximately 100 feet behind the ship and fired between 500 and 2,000 pounds of pressure at 10 second intervals. It was the sound source (in conjunction with a smaller air gun for better definition) for seismic profiling records. The larger gun, a 120 cubic inch PAR, provided deeper penetration. With these guns seismic records provided a reliable picture of sub-ocean bottom topography. November 1976.

Technician William J. Brennan, aboard the D/V Glomar Challenger (ship) helped place a new air gun into the water for a che...