Two rare German Enigma Machines, one dating from 1940-1941 and the other to 1944, will highlight Bonhams' Cameras, Scientific and Mechanical Musical Instruments auction in London on October 29.
The two machines will sell as separate lots, each with an estimate of £30,000-50,000 ($48,000-81,000).
The Enigma was the famously "unbreakable" code used by the Nazis during the second world war. The machines were constantly updated to prevent the code from being cracked, or destroyed to stop them falling into enemy hands - making them exceptionally rare.
An early example, dating to 1938, sold at Auction Team Brekker in Koeln, Germany for $89,186 last year.
A gilt and patinated brass mechanical equinoctial dial made in Austria in the 18th century will be another highlight of the sale. The device, an ingenious method of accurately measuring time via sunlight, carries an estimate of £14,000-18,000 ($17,000-21,000).
It closely resembles the work of Franz Antonio Nitzl (1671-1754) who was a member of staff at the Engineering School of Linz from 1708.
A Nicole Freres grand format overture cylinder music box will carry an estimate of £12,000-18,000 ($19,000-29,000).
The cylinder plays four overtures from a brass tune sheet, and is housed in an ebonised wood and walnut veneered case with an ornate brass inlay.
A gilt brass compendium attributed to Augustine Ryther circa 1589 also features, with a valuation of £12,000-16,000 ($19,000-26,000).
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