The Stanhope Demonstrator: An Instrument for Performing Logical Operations. Separately-paginated offprint from: Mind, Vol. IV

"THE WORLD'S FIRST LOGIC MACHINE" (MARTIN GARDNER). First edition, extremely rare separately-paginated offprint, inscribed by the author, of the first published description of "the world's first logic machine" (Martin Gardner), designed by Charles Stanhope, third Earl Stanhope, in the 1770s. "His system consisted essentially in the reduction of both positive and negative propositions to a single form, that of the identity of two things or classes of things, and in the employment of symbols to represent the quantities of things involved in such propositions. In his general use of logical symbols and his manipulation of them he introduced a new rigour into the science and looked ahead towards Boole's virtual reduction of logic to a branch of pure mathematics" (Beatty, p. 206). Stanhope "succeed[s] in demonstrating that the consequences of two logical statements are capable of solution by mechanical means. Although earlier logicians had proposed mechanical contrivances (e.g., Euler's circles), Stanhope was the first to construct an instrument to deal with this kind of problem" (ibid., p. 208). "The first model was constructed in 1775. It consisted of two slides coloured red and gray mounted in a square brass frame. This could be used to demonstrate the solution to a syllogistic type of problem in which objects might have two different properties and the question was how many would have both properties. Scales marked zero to ten were used to set the numbers or proportions of objects with the two properties. This form of inference anticipated the numerically definite syllogism which Augustus De Morgan laid out in his book, Formal Logic, in 1847 . At least four of the devices with this square style were built. In 1879, Robert Harley wrote that he had one which he had been given by Stanhope's great-grandson, Arthur, who had kept one. The other two were owned by General Babbage - the son of Charles Babbage, who continued his work on the Analytical Engine. One of the devices was donated to the Science Museum, London by the last Earl in 1953. Other styles, such as circular models, were constructed, but these were less convenient" (Wikipedia). "Stanhope's speculations on logic covered a period of some thirty years, but he published nothing about his logical views beyond printing on his own hand press several early chapters of an unfinished work, titled The Science of Reasoning Clearly Explained upon New Principles. These chapters were circulated only among a few acquaintances. In a letter written shortly before his death, he advises a friend not to discuss his logical methods with others lest 'some bastard imitation' of his views appear before the publication of his projected work [which was, in fact, never completed or published]. It was not until 60 years later that one of the earl's contrivances, together with relevant letters and notes, came into the hands of Rev. Robert Harley, who then published an account of the demonstrator and the logic on which it was based" (Gardner, pp. 80-81). Harley notes that "Earl Stanhope's Demonstrator is much less powerful as a logical instrument than Professor Jevons' machine, but the former is undoubtedly a distinct anticipation of the latter. It is probably the first attempt ever made to solve logical problems by mechanical methods." OCLC lists 5 copies worldwide (Trinity College, Cambridge; National Library of Wales; Glasgow; Chicago; Huntington); not in BL. Not on RBH. Provenance: Inscribed on upper wrapper, 'George Wooding Esqre. / With the Writer's kind regards.' "Although Ramon Llull made use of rotating discs to facilitate the working of his eccentric system of reasoning, his devices are not logic machines in the sense that they can be used to solving problems in formal logic. The inventor of the world's first logic machine in the strict sense of the term was a colorful eighteenth-century British statesman and scientist, Charles Stanhope, third Earl Stanhope (1753-1816). His curious device, wh.…