Rare notebook by British code breaker Alan Turing expected to fetch S$1.37 million at auction

NEW YORK — A handwritten notebook by British code-breaking genius Alan Turing is expected to bring at least US$1 million (S$1.37 million) at an auction in New York today (April 13).

The 56-page manuscript was written when the mathematician and computer science pioneer was working to decipher the seemingly unbreakable Enigma codes used by the Germans in World War II. It contains Mr Turing’s complex mathematical and computer science notations and is believed to be the only extensive Turing manuscript in existence, according to Bonhams, which is offering the manuscript for sale.

The story of how Mr Turing and a team of cryptanalysts broke the code was portrayed in the 2014 movie The Imitation Game, starring Benedict Cumberbatch in the role of Mr Turing.

The notebook dates from 1942, when Mr Turing was working at Britain’s wartime code and cypher school Bletchley Park. In one entry, Mr Turing writes about a complex calculus notation.

“The Leibniz notation I find extremely difficult to understand in spite of it having been the one I understood the best once! It certainly implies that some relation between x and y has been laid down eg, y(equals)x2+3x.”

The sale also includes a working German Enigma enciphering machine. The three-rotor device was manufactured for the German military in July 1944. It is expected to sell for between US$140,000 and US$180,000.

Mr Turing was prosecuted for being gay at a time when it was illegal in Britain. He was convicted of indecency in 1952 and agreed to undergo hormone treatment as an alternative to imprisonment in order to “cure” his homosexuality.

He died in 1954 of cyanide poisoning. It was ruled a suicide, although his family and friends believed it might have been accidental. The notebook was among the papers he left in his will to friend and fellow mathematician Robin Gandy.

Mr Gandy gave the papers to The Archive Centre at King’s College in Cambridge in 1977. But he kept the notebook, using its blank pages for writing down his dreams at the request of his psychiatrist. Bonhams describes Mr Gandy’s entries as highly personal; the notebook remained in his possession until he died in 1995.

At the beginning of his journal, Mr Gandy writes: “It seems a suitable disguise to write in between these notes of Alan’s on notation, but possibly a little sinister; a dead father figure, some of whose thoughts I most completely inherited.”

Bonhams said the seller wished to remain anonymous. Part of the proceeds will be donated to charity. AP