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IX. 



ON A PROPOSED ANALYTICAL MACHINE. 

 By PERCY E. LTJDGATE. 



(communicated by professor a. W. CONWAY, M.A.) 



[Read Februaky 23. Ordered for Publication March 9. Published April 28, 1909.] 



I PURPOSE to give in this paper a short account of the result of about six 

 years' work, undertaken by me with the object of designing machinery 

 capable of performing calculations, however intricate or laborious, without 

 the immediate guidance of the human intellect. 



In the first place I desire to record my indebtedness to Professor 

 0. V. Boys, F.R.S., for the assistance which I owe to his kindness in entering 

 into correspondence with me on the matter to which this paper is devoted. 



It would be difficult and very inadvisable to write on the present subject 

 without referring to the remarkable work of Charles Babbage, who, having 

 first invented two Difference Engines, subsequently (about eighty years ago) 

 designed an Analytical Engine, which was shown to be at least a theoretical 

 possibility ; but unfortunately its construction had not proceeded far when 

 its inventor died. Since Babbage's time his Analytical Engine seems to 

 have been almost forgotten ; and it is probable that no living person 

 understands the details of its projected mechanism. My own knowledge of 

 Babbage's Engines is slight, and for the most part limited to that of their 

 mathematical principles. 



The following definitions of an Analytical Engine, written by Babbage's 

 contemporaries, describe its essential functions as viewed from different 

 standpoints : — 



" A machine to give us the same control over the executive which we 

 have hitherto only possessed over the legislative department of 

 mathematics."' 

 " The material expression of any indefinite function of any degree of 

 generality and complexity, such as, for instance : — F {x, y, z, log x, 

 sin y, &c.), which is, it will be observed, a function of all other 

 possible functions of any number of quantities."" 



^ C. Babbage : " Passages from the Life of a Philosopher," p. 129. 

 - R. Taylor's "Scientific Memoirs," 1843, vol. iii., p. 691. 



SCIENI. PEOC, K.D.S., VOL. XII., NO. IX. P 



