399 - Turing (Alan).- Alan Turing's Slide Rule, engraved initials "A.M.T. Noli Hoc Furari" to verso, in original cloth box with his ownership lettered in gilt, "A.M. Turing. Princeton - 1936" (rubbed, slight wear to extremities), alongside other ephemera including items relating to Power-Samas and Hollerith accounting machines, a few scientific or technical pamphlets, a pair of compass, mechanical pencil, fountain pen, unused postcards, c.1925 guide to Guildford, housed within early 20th-century letter box, approx. 330 x 230 mm, [mid.1920s-40s].

Turing (Alan).- Alan Turing's Slide Rule, engraved initials "A.M.T. Noli Hoc Furari" to verso, in original cloth box with his ownership lettered in gilt, "A.M. Turing. Princeton - 1936" (rubbed, slight wear to extremities), alongside other ephemera including items relating to Power-Samas and Hollerith accounting machines, a few scientific or technical pamphlets, a pair of compass, mechanical pencil, fountain pen, unused postcards, c.1925 guide to Guildford, housed within early 20th-century letter box, approx. 330 x 230 mm, [mid.1920s-40s]. *** Alan Turing's slide rule, seemingly from the time he was completing his doctorate at Princeton University. The Latin inscription translates to "Don't Steal This", reflecting Turing's protective nature over his property. During his time at Princeton University from September 1936 to July 1938, Turing was studying cryptology, and built three of four stages of an electro-mechanical binary multiplier. In November 1936, Turing submitted a proof titled "On Computable Numbers, with an Application to the Entscheidungsproblem". He obtained his PhD from the Department of Mathematics, and his dissertation, Systems of Logic Based on Ordinals, introduced the notion of relative computing and the concept of ordinal logic. This thesis was later republished in the journal Proceedings of the London Mathematical Society in 1939. The Power-Samas and Hollerith magazines on accounting machines are of interest due to their connection to Turing's legacy. Both companies manufactured punch-card computing systems vital to production and logistics during the war; the former also manufactured the British equivalent of the Enigma coding machine. Hollerith manufactured the Bombes designed by Turing for breaking the enigma code. The Bombes used the electromechanical technology of Hollerith/BTM machines, and in particular a 'wire bristle' commutator contact, similar to the one shown in the Hollerith magazine. Scientific pamphlets included comprise of: Douglas R. Hartree's "Calculating Machines: Recent & Prospective Developments and their impact of Mathematical Physics", 1947; Arthur Stanley Eddington's "The Romanes Lecture: The Theory of Relativity and its Influence on Scientific Thought", 1922; Moritz Geiger's "Die philosophie Bedeutung der Relativitätstheorie", 1921; and Felix Klein's "The Present State of Mathematics".