According to Hunley lore, there were reports from both Confederates and Union sailors that a blue light was seen that February night in 1864 when the hand-cranked sub sent the Union blockade ship Housatonic to the bottom of Charleston Harbor.
It’s long been thought the blue light was a sort of mission accomplished signal from the Hunley and its eight-man crew before the sub sank. The cause of the sinking is another mystery.
But the small lantern shown Thursday at the lab where the sub is housed has a clear lens and senior conservator Paul Mardikian says there’s no indication there was any sort of blue film over the lens.
Mardikian showed both the conserved lantern and a photo of the lantern corroded and covered in hardened sediment when the submarine when it was raised in 2000. The iron lantern is covered with a thin layer of tin and required several years of chemical treatment and painstaking work with hand tools to clean.
Mardikian said if the lantern was a signaling device it would likely have had a blue glass lens.
“And we don’t have a blue glass, and so where does the story of the blue light come from?” asked Mike Scafuri, a staff archaeologist for the Hunley project. “The myth is that the Hunley signaled shore at the completion of the mission and supposedly onshore they saw this light.”
The facts, he said, are that a Union sailor holding onto the rigging of the sinking Housatonic saw a blue light in front of another Union vessel coming to the aid of the Housatonic.
“Did he see a light that was colored blue or did he see a light that was referred to as a blue light?” Scafuri asked.
During the Civil War, emergency flares and other signals – regardless of color – were sometimes referred to as blue lights. Scafuri said that’s akin today to people referring to police lights as blue lights even if they might be of another color.
Another possible explanation is that the lantern light, seen from a distance, appeared blue because of water vapor. He suspects the oil lantern was a sort of flash light for the crew, lighting the sub’s interior and helping the crew get in and out.
It’s also unclear why the Confederates would want to signal shore and draw possible attention from the Yankee ships.
Even before the conservation of the lantern, scientists had a good idea what it looked like.
X-rays taken before the corrosion was removed, drawings and pictures were sent to students at Hamburg Area High School west of Allentown, Pa. The students made several replica lanterns, one of which is in the lab museum, Scafuri said.