Benjamin Franklin is widely known as one of the founding fathers of the United States, a diplomat, a scientist, and a writer. But did you know that he also had a connection to a grisly anatomy school in London?

Franklin lived in London for nearly two decades before returning to America in 1776. He rented a house at 36 Craven Street, where he conducted experiments, wrote letters, and entertained guests. But more than 200 years later, a shocking discovery was made in the basement of his former residence.
In 1998, conservationists were doing repairs on the house, looking to turn it into a museum. They found a secret, windowless room under the garden, containing the remains of 15 people. Six were children. The bones showed signs of dissection and surgical procedures.
Who were these people and why were they buried there? Was Franklin involved in some sinister activities?
“The most plausible explanation is not mass murder, but an anatomy school run by Benjamin Franklin’s young friend and protege, William Hewson,” said the Guardian in 2003. Still, in Franklin’s time, anatomy lessons were a dark, ethically ambiguous business.
Hewson was a pioneer in the field of hematology, the study of blood. He isolated the key protein in the blood clotting process, fibrinogen, and called it “coagulable lymph”. He also experimented with mercury and turtles to show the lymphatic system.
Hewson trained in Edinburgh and studied with famous anatomist William Hunter, becoming a partner in Hunter’s school at Great Windmill Street, London. He later married Mary Stevenson, the daughter of Franklin’s landlady, and opened his own anatomy school at Craven Street.
But getting human bodies for dissection was not easy or legal. Hewson had to resort to grave robbing or snatching corpses from the gallows. He smuggled them into his basement lab and dissected them for his students. When he was done with them, he buried them in a pit under the garden.
Franklin was probably aware of the illegal studies going on in his building, but it’s doubtful that he was involved himself. He helped Hewson get elected to the Royal Society and receive the Copley Medal for his work.
“I should think it no Trouble to hear their Complaints if I could be of the least Use in accommodating their Differences; but since that was not likely, I could only wish as I had a Regard for both, that they would go on to the End of their Term as quietly as possible, since that would be most to the Credit of both,” Franklin wrote to Hunter in a letter.
The secret bones in Franklin’s basement reveal a fascinating and macabre side of his life in London. They also shed light on the history of anatomy and medicine in the 18th century.
If you want to learn more about this story, you can visit the Benjamin Franklin House museum at 36 Craven Street. You can also see some of the bones and artifacts on display in the Seminar Room.
“It seems 36 Craven Street was the perfect place for an anatomy school: Hewson was married to the landlady’s daughter; the tenant, Ben Franklin, was a trusted friend; and the house lay between two sources of material,” wrote Londonist.
But don’t expect to find any skeletons in Franklin’s closet. He was too smart to leave any evidence behind.
Relevant articles:
– Why Was Benjamin Franklin’s Basement Filled With Skeletons?, Smithsonian Magazine, October 3, 2013
– Craven Street Bones, Benjamin Franklin House, no date
– William Hewson (surgeon), Wikipedia, last edited on November 28, 2021
– The Secret Bones In Benjamin Franklin’s Basement, Londonist, May 31, 2016