PREFACE TO THE SECOND EDITION. xv 



work, printed by the Earl at his own press, which show 

 that he had arrived, before the year 1800, at the principle 

 of the quantified predicate. He puts forward this prin- 

 ciple in the most explicit manner, and proposes to employ 

 it throughout his syllogistic system. Moreover, he con- 

 verts negative propositions into affirmative ones, and 

 represents these by means of the copula " is identic with." 

 Thus he anticipated, probably by the force of his own 

 unaided insight, the main points of the logical method 

 originated in the works of George Bentham and George 

 Boole, and developed in tliis work. Stanhope, indeed, has 

 no claim to priority of discovery, because he seems never 

 to have published his logical wi'itings, although they were 

 put into print. There is no trace of them in the Britisli 

 Museum Library, nor in any other library or logical work, 

 so far as I am aware. Both the papers and the logical 

 contrivance have been placed by the present Earl Stanhope 

 in the liands of the Eev. Eobert Harley, F.E.S., who will, 

 I hope, soon publish a description of them.^ 



By the kindness of Mr. Harley, I have been able to 

 examine Stanhope's logical contrivance, called by him the 

 Demonstrator. It consists of a square piece of bay-wood 

 with a square depression in the centre, across which two 

 slides can be pushed, one being a piece of red glass, and 

 the other consisting of wood coloured gray. The extent 

 to which each of these slides is pushed in is indicated by 

 scales and figures along the edges of the aperture, and the 

 simple rule of inference adopted by Stanhope is : " To the 

 gray add the red and subtract tlie liolon^" meaning by 

 liolon {okov) the whole width of the aperture. This rule 

 of inference is a curious anticipation of De Morgan's 

 numerically definite syllogism (see below, p. 168), and of 

 inferences founded on what Hamilton called " Ultra-total 

 distribution." Another curious point about Stanhope's 



^ Since the above was written Mr. Harley h;i.s read an account of Stiin- 

 hope's lo;;ica] remains at tlie Dublin Meetinj^ (1878) of tlie British 

 Assoniatiou. The ])aper will be printed in Miml. (Note added Novenilitr, 

 1878.) 



