Inch by inch they worked their way into a gaping hole on the starboard bow of the hulk. The planking that framed the cavernlike opening was shattered and twisted as though a giant fist had rammed into the ship. They began to uncover artifacts: a shoe, the hinge from an old chest, brass calipers, tools, even a piece of cloth.

It was an eerie sensation to touch man-made objects that no one had seen in 127 years.

One of the men paused to check their air gauges. He calculated they could work another ten minutes and still have a safe supply of breathable air to reach the surface.

They turned off the valve on the airlift, stopping the suction, while they waited for the river current to carry away the cloud of disturbed silt. Except for the exhaust of their breathing regulators, it became very still. A little more of the wreck became visible. The deck timbers were crushed and broken inward. Coils of rope trailed into the murklike mud-encrusted snakes. The interior of the hull seemed bleak and forbinding. They could almost sense the restless ghosts of the men who had gone down with the ship.

Suddenly they heard a strange humming-not the sound made by the outboard motor of a small boat, but heavier, like the distant drone of an aircraft engine. There was no way of telling its direction. They listened for a few moments as the sound grew louder, magnified by the density of the water. It was a surface sound and did not concern them, so they reactivated the airlift and turned back to their work.

No more than a minute later the end of the suction pipe struck something hard. Quickly they closed off the air valve again and excitedly brushed away the mud with their hands. Soon they realized they were touching, not wood, but an object that was harder, much harder, and covered with rust.

To the, support crew on the barge over the wreck site time seemed to have reversed itself. They stood spellbound as an ancient PBY Catalina flying boat made a sweeping bank from the west, lined up on the river and kissed the water with the ungainly finesse of an inebriated goose. The sun glinted on the aquamarine paint covering the aluminum bull, and the letters NUMA grew larger as the lumbering seaplane taxied toward the barge. The engines shut down; the co-pilot emerged from a side hatch and threw a mooring line to one of the men on the barge.