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The larger one, subtitled Mubashir Ibn Ahmad al-Razi to Charles Babbage, runs to 700 lots and includes works from the period 1180-1813. The second day’s sale is billed as Babbage to Turing.

A 15-lot section of the bigger catalogue that has its own introductory essay, ‘Galileo and his Compass’, includes another copy of the Discorsi… mentioned in the story above. However, the star turn is a presentation copy of the Difesa… contro alle calumnie & imposture di Baldessar Capra. Published in 1607, it is an attack by Galileo on a rival who had laid claim to his invention of the compasso, a multi-purpose calculating instrument, plagiarised a manual that Galileo had published to explain its use, and generally impugned his reputation.

Two years a copy of the Difesa… in the Giancarlo Beltrame library, bound with a copy of Galileo’s original instruction manual, Le operazioni del compasso geometrico, et militare of 1606, made £200,000 at Christie’s.

The Tomash copy of the Discorsi…, inscribed by its author for Girolamo Cappello, a Venetian diplomat, senator and administrator of Padua university, is estimated at £300,000-400,000.