Austin pondered his next move. Like most men who follow the sea, he had the deepest respect for watery graves. He could surface and report the find to the authorities. But the heavy hand of police divers could destroy whatever secrets the wreck might have yielded.

He wrapped his arms around the helmet and carefully wrestled it free. The skull dropped out of the bottom and landed upright. Austin took comfort in the fact that the dead diver was still grinning.

He avoided the baleful eye sockets and took a lift bag from a pouch. He tied the lines from the bag to the helmet’s neck and inflated the lifter with air from his tank. He inflated his buoyancy compensator, grabbed the helmet, and slowly ascended to the surface.

Zavala had watched the primitive salvage effort on the ROV’s monitor. He saw Austin’s head pop up at the surface and threw him a line. Austin tied the line to the helmet so it wouldn’t sink. He handed Zavala his air tank, weight belt, and fins, and then he climbed a ladder into the boat.

They bent their backs to the line and hauled the helmet onto the deck.

Austin pulled his hood off and knelt next to the helmet. “This is an old-timer,” he said. “Probably been down there for years.”

Zavala examined the air hose fitting and the ear plates and face-plates. He ran his fingers over the metal dome. “The workmanship is incredible. It’s made of brass and copper.” He tried to lift the helmet and the attached breastplate. “This baby must weigh more than fifty pounds. The guy who wore this thing must have been as tough as nails.”

“Not tough enough,” Austin said.

“I suspected that was the case,” Zavala said with a glance over the side. “I wonder who he was.”

Austin scraped growth away to reveal an oval piece of metal, engraved with the helmet’s manufacturer, that was riveted to the front of the breastplate. The engraving said that the helmet had been made by the MORSE DIVING EQUIPMENT COMPANY, of Boston. Underneath the manufacturer’s name was a serial number.

“Maybe this will tell us.”

He used a cell phone to call the maritime history division at NUMA. He identified himself to a researcher, who said her name was Jennifer, and gave her the information from the manufacturer’s plate. Jennifer asked for the numbers on the brail straps as well, and said she would run a search and call him back.