Enigma Code Breaker Turing’s Notebook Sells for $1 Million

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Alan Turing
Alan Turing became famous for building a machine that cracked the German military encrypted messaging system, Enigma, during World War II. Photographer: Spencer Platt/Getty Images

World War II code breaker Alan Turing’s handwritten notations about math and computer science sold for $1.03 million at Bonhams in New York.

Turing, whose life was depicted in “The Imitation Game,” wrote in the notebook from 1942 to 1944, when the British mathematician led a team trying to crack Nazi Germany’s encrypted messaging system. The unpublished notebook is the only extensive Turing manuscript known to exist, according to Bonhams.

The notebook sold Monday in about three minutes at the hammer price of $850,000, and with the commission met its $1 million estimate. An Enigma machine used by the German military to code messages sold for $269,000, above its high estimate of $180,000. The buyers wished to remain anonymous, Bonhams said. Turing’s nephew, Sir John Dermot Turing, attended the sale.

Publicity can help push up prices and lend cache to memorabilia. Benedict Cumberbatch portrayed Turing in the movie, which received eight Academy Award nominations.

“Obviously that’s why whoever owned it chose this as the right time,” said Laura Woolley, a memorabilia appraiser in Los Angeles.

Other Projects

Although Turing wrote in the notebook while at Bletchley Park, a country house in Buckinghamshire that was the center of British secret operations, its contents aren’t related to his Enigma work. The manuscript refers to other projects he was working on in his free time, said Cassandra Hatton, a specialist in fine books and manuscripts at Bonhams.

“This is a man who thought about mathematics day and night,” Hatton said. “It shows us what he was doing to unwind.”

The notebook “shows you how methodical he was,” Hatton said. “It gives us insight into the specific problems that he was concerned with.”

Turing was gay, a crime in England at the time. Following his 1952 conviction for gross indecency, he underwent hormonal therapy for chemical castration rather than go to prison. He committed suicide two years later at age 41. Turing received a posthumous royal pardon in 2013.

Turing left his papers to his friend and fellow mathematician Robin Gandy. In 1977, Gandy donated all of Turing’s writings except the manuscript to the Archive Center at King’s College, and it remained hidden until Gandy’s death in 1995. Gandy’s executor sold it to the current owner, who wished to remain anonymous. A portion of the proceeds will be donated to Human Rights Campaign, according to Bonhams.

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