Bonhams : TURING (ALAN) - THE DELILAH PROJECT The papers of Alan Turing and Donald Bayley relating to the Delilah project.
The papers of Alan Turing and Donald Bayley relating to the Delilah project, a wartime collaboration seeking to develop a speech encryption system, including Turing’s mathematical proofs and Bayley’s transcriptions of Turing’s lectures on electrical circuit theory, comprising: i) Laboratory notebook, recording the results of experiments testing the performance of Delilah’s various electrical circuits, the first 12 pages and 8 adjacent graphs in Turing’s hand, including 7 line diagrams concerning the development and testing of the Key Generator (“Measurement of ‘A ₂ -pulse’ for Multivibrators”, “Measurement of ‘Heaviside function’”, “Second Experiment for measurement of the A ₂ -pulse”, “Linearity Test for Pulse Modulation”, “6H6 Characteristic”, “Repetition of Linearity Test…”, “… with various grid leaks”, “Characteristic of H3 Rectifier”, “Harmonic Analyser Output Stage Characteristics”, “Relative Response of Harmonic Analyser v. Beat freq.”, “Relative response versus input”), blue ink and pencil; additional single loose leaf of voltage calculations written in three columns; the following 12 pages in Bayley’s hand, including 4 graphs, blue ink and pencil; the final 18 leaves of later notes by Bayley on mundane household matters such as decorating and DIY projects, written in blue biro; later note in Bayley’s hand clipped to first page “Notebook/ Used in/ Delilah Development/ With Notes In/ Turing’s Hand”, 70 leaves (23 blank), dust-staining and marks, some water damage to front endpaper and first leaf, original green board covers, pencil inscription “4/-” upper right corner, stained and worn, 4to (258 x 204mm.) , [Hanslope Park, 1943-?1945 and later]; ii) Turing’s autograph mathematical calculations headed “Bandwidth Theorem”, his proof written out for Bayley, and incorporating a line diagram, further notes on logic formulae in pencil on reverse of first leaf, black ink, 3 pages on two leaves, some marks, creased at horizonal fold, 4to (289 x 220mm.) ; accompanied by Donald Bayley’s later autograph note “Delilah is an application of the bandwidth theorem. This is Turing’s proof. He wasn’t the first to do so…”; iii) Turing’s ‘Red Form’ autograph mathematical notes possibly relating to Delilah’s key generator and the Fourier Theorem, 13 numbered leaves, in pencil on the blank reverse of ‘Red’ (or Intercept) Forms (Army Form C2133), with 7 additional leaves in Bayley’s hand and another unidentified hand, 3 of these possibly in the hand of Turing, 20 leaves, dust-staining, frayed, 4to (250 x 189mm.) ; iv) Turing’s autograph mathematical calculations headed “Determination of cut-off volts”, comprising a diagram with equations beneath, dark blue ink on the reverse of a red-printed Y Service Form S.323, filled in with pencil notes logging intercepts from Forfar on 23 November 1943, one page, perforations at lower edge, roughly torn on left hand side, three filing holes, frayed, 4to (249 x 197mm.) ; v) Turing’s autograph mathematical calculations headed “Faltung”, including a line diagram, explaining the mathematics of convolutions, using the shape of a mushroom as an analogy, in blue ink, on the reverse of a red-ruled radio log sheet stamped with the names of various intercept stations in Scotland, Northern Ireland, Norfolk, Devon and Cornwall (‘Thurso’, ‘Cupar’, ‘Sandridge’, ‘Stockland’, ‘St Erth’, ‘Wymondham’) dated 9 August 1942, intercepted enemy transmission frequencies logged in pencil, with the note ‘Reported By Hanslope. No trfc.’ And ‘No fix. Poss between Genoa and Naples area’ in red ink, one page, filing hole top left, some show-through of red ink from reverse, ink blots, dust-staining, sheet frayed and creased, closed tear not affecting text, 4to (262 x 195mm.) ; vi) Bayley’s school file titled ‘Queen Mary’s School/ Walsall’ in gilt on upper cover, the contents prefaced with a later note by Donald Bayley (“Some University maths notes but mainly notes of training given by Alan Turing during after dinner sessions at Hanslope Park. Some pp in his own hand…”), containing 90 leaves (180 numbered pages) of Bayley’s transcriptions of lectures given by Turing on mathematics for electrical engineers at Hanslope Park, prefaced by a 2-page reference list of standard mathematical forms in red ink; some 140 further leaves of Bayley’s notes taken at university including sections on “Statics” and “Kinematics”, c.14 sheets of calculations loosely inserted, some on orange or pink paper, several blank pages, Bayley’s ownership inscription and address inside upper cover in ink (“20 Chantry Ave/ Walsall/Staffs”, “D. Bayley./ Birmingham University/ Elect Eng Dept.”), 230 leaves dust-staining, discolouration and marks, edges frayed, the majority 4to, some on smaller lined paper, all contained in ‘Loxton’ binder by Hunt & Broadhurst Ltd., Oxford, worn, 4to (278 x 235mm.) ; vii) Bundle of loose notes written by Turing and Bayley found in the file, including two foolscap leaves by Turing concerning different electrical problems and Bayley’s summary notes concerning topics covered in Turing’s evening lectures, cross-referencing his lecture notes (“Submarine cable see p.40 of notebook”), c.6 pages in Turing’s hand, the rest in Bayley’s and an unidentified hand, ink and pencil, 13 leaves in all, 6 written on reverse of Red Forms, dust-staining, creased and frayed, some loss, 4to (250 x 189mm.), two foolscap leaves 325 x 200mm., one leaf 227 x 288mm. ; viii) Turing’s autograph mathematical calculations headed “Problem… Discuss the convergence of the sequence x…”, probably written out carefully for Bayley’s benefit, densely written in dark blue ink, 2 pages, creased at horizontal fold, 4to (288 x 215mm.) .

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