
Researchers have found human remains inside the H.L. Hunley, the first submarine in history to sink an enemy warship, after it emerged from a 75,000-gallon tank of chemicals.

The submarine, which fought for the confederacy in the US civil war, was sunk near North Charleston, South Carolina, in 1864 by its own torpedo, killing all eight men on board.

The Hunley was raised from the bottom of the ocean in 2000, and two scientists have spent the past 17 years collecting the crew's remains and restoring the vessel as part of a painstaking cleanup operation.

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Alongside the tooth, the researchers announced that they had finally cracked how the submarine was propelled through the water. Hidden underneath the rock-hard stuff scientists call 'concretion' was a sophisticated set of gears and teeth on the crank in the water tube that ran the length of the 40-foot sub

THE H.L. HUNLEY'S DOOMED TRIPS The Hunley's successful but doomed final mission was actually its third trip. The submarine sank once while docked with its hatches open in August 1863. Only three of the eight men on board escaped and survived. In October 1863, designer H.L. Hunley led another eight-man crew who planned to show how the sub operated by diving under a ship in Charleston Harbor. They never surfaced, but the sub was found weeks later and brought back to the surface. That crew was interred in graves that ended up below The Citadel's football stadium for 50 years. Advertisement

While most of the remains were removed and ceremonially buried at Magnolia Cemetery in 2004, the researchers found a tooth stuck in a concrete-like mass of sand, mud and other debris at crank handle position Number 3.

It is believed that this is the position where crew member Frank Collins sat, a Confederate Navy Seaman who was just 24 years old when he sank with the Hunley.

Project lead archaeologist Michael Scafuri told the Post and Courier that the tooth loss was 'post-mortem', meaning that long after the sinking, the tooth came loose during the decomposition process and stuck to the crank handle where it corroded with the iron.

The find was made as the pair of scientists tasked with the submarine's cleanup gave a project update during a media brief this week.

Alongside the tooth, the researchers announced that they had finally cracked how the submarine was propelled through the water.

Hidden underneath the rock-hard stuff scientists call 'concretion' was a sophisticated set of gears and teeth on the crank in the water tube that ran the length of the 40-foot sub.

These gears enabled the crew rotating the crank to propel the sub faster by moving water more quickly through the tube. Pictured is conservator Anna Funke spraying sodium hydroxide on the H.L. Hunley in the Warren Lasch Conservation Center in North Charleston

The events of the submarine's sinking remain a mystery - some guess the crew was too close to the torpedo and were knocked unconscious when it exploded, or perhaps miscalculated how long their oxygen would last

The submarine, which fought for the confederacy in the US civil war, was sunk near North Charleston, South Carolina, in 1864 by its own torpedo, killing all eight men on board. The Hunley was raised from the ocean in 2000, and two scientists have spent the past 17 years collecting the crew's remains and restoring the vessel as part of a painstaking cleanup operation

These gears enabled the crew rotating the crank to propel the sub faster by moving water more quickly through the tube, conservator and collections manager Johanna Rivera-Diaz said.

The biggest surprise for Rivera-Diaz? Discovering that some of the men wrapped the crank handle in thin metal tubes covered with cloth to try to prevent blisters.

'You get really concentrated on a specific area working every day. I was finishing the crank system. One day, when I was through, I just stepped back and "Wow, this looks amazing",' she said.

HOW THE HUNLEY SUBMARINE MOVED Alongside the tooth, the researchers announced that they had finally cracked how the submarine was propelled through the water. Hidden underneath the rock-hard stuff scientists call 'concretion' was a sophisticated set of gears and teeth on the crank in the water tube that ran the length of the 40-foot sub. These gears enabled the crew rotating the crank to propel the sub faster by moving water more quickly through the tube, conservator and collections manager Johanna Rivera-Diaz said. The biggest surprise for Rivera-Diaz? Discovering that some of the men wrapped the crank handle in thin metal tubes covered with cloth to try to prevent blisters. 'You get really concentrated on a specific area working every day. I was finishing the crank system. One day, when I was through, I just stepped back and "Wow, this looks amazing",' she said. Advertisement

For 17 years, researchers have been painstakingly cleaning a century and a half of sand, sediment and corrosion from the historic submarine.

Their goal is to get it looking as close as it appeared on its mission as possible by removing gunk using a mixture of sodium hydroxide and a mild electrical current.

This gradually softens the concrete-hard buildup of sand, mud and shells that built up inside the vessel during the 140 years it was buried off Sullivan's Island, so that the debris can be removed later.

Researchers have found human remains inside the H.L. Hunley (pictured), the first submarine in history to sink an enemy warship. It is believed the tooth belonged to a Confederate Navy Seaman who was just 24 years old when he died

This graphic reveals the Hunley's final moments as it drove its spar-based torpedo into the hull of a Union blockade ship

Confederate submarine H.L. Hunley (1863-1864). This image shows an inboard profile and plan drawings, after sketches by W.A. Alexander, who directed her construction

The pair drain the 75,000-gallon tank of water and chemicals three times a week for several hours at the Confederate sub's home in North Charleston, South Carolina.

Then, they go to work in full protective gear, bent around nooks and crannies, gingerly chipping the grime off the H.L. Hunley, all for moments like this, when they can show the world something new.

Scientists hope to resolve the mystery of how the sub sunk by cleaning the entire interior of the sub over the next several years.

The sub was only 4 feet in diameter. Eight schoolchildren can barely cram themselves into a replica nearby at the Warren Lasch Conservation Centre. Pictured is an artist's impression of the vessel

Some guess the crew was too close to the torpedo and were knocked unconscious when it exploded, or perhaps miscalculated how long their oxygen would last.

It took one year to remove all the crud from its hull, and nearly two more to clean out the much smaller crew compartment, Mr Rivera-Diaz said.

'It's tough physically to do this every day. You are wearing special suits and using chemicals with high pH levels,' she said.

The sub itself is only 4 feet in diameter. Eight schoolchildren can barely cram themselves into a replica nearby at the Warren Lasch Conservation Centre.

Up next for Mr Rivera-Diaz is cleaning the conning tower. Scientists have determined that it had a lock, but don't know why. The submarine was too cramped for the men to move around.

The eight crew members were buried in an elaborate ceremony at a Confederate cemetery in Charleston in 2004.

While most of the remains of the Hunley's wreck were removed and ceremonially buried at Magnolia Cemetery in 2004, the researchers found a tooth stuck in a concrete-like mass of sand, mud and other debris at crank handle position Number 3

Alongside the tooth, the researchers announced that they had finally cracked how the submarine was propelled through the water

They were the sub's commander, Lt. George Dixon of Alabama, James A. Wicks, a North Carolina native living in Florida, Frank Collins of Virginia, Joseph Ridgaway of Maryland and four foreign-born men about whom less is known. One is still only known as 'Miller.'

The Hunley's successful but doomed final mission was actually its third trip. The submarine sank once while docked with its hatches open in August 1863. Only three of the eight men on board escaped and survived.

In October 1863, designer H.L. Hunley led another eight-man crew who planned to show how the sub operated by diving under a ship in Charleston Harbor.

They never surfaced, but the sub was found weeks later and brought back to the surface. That crew was interred in graves that ended up below The Citadel's football stadium for 50 years.

Pictured is the Hunley as it was removed from the ocean floor in 2000. Scientists have since spent 17 years restoring the vessel

Since the submarine was found and removed from the ocean (pictured), the researchers' goal has been to get it looking as close as it appeared on its mission as possible by removing gunk using a mixture of sodium hydroxide and a mild electrical current

James McClintock (left and right) was one of the designers of the doomed Confederate submarine H.L. Hunley (1863-1864)

Inboard profile and plan drawings, after sketches by W.A. Alexander, who directed the submarine's construction

Autographed signed letter dated 15 August 1863 from Horace Lawson Hunley to James R. McClintock, the inventor of the Confederate submarine H.L. Hunley

Park and Lyons machine shop building, Mobile, where the Confederate submarine H.L. Hunley was constructed in 1863. Located at the corner of Water and State Streets, in Mobile, this old building housed the Gill Welding and Boiler Works when photographed in about 1960