500 



It is well known that Mr. Babbage was the first person who con- 

 ceived the idea of performing all these systems of additions mechani- 

 cally, and thereby saving both the mental labour and the risk of 

 error attending their calculation in the ordinary way. This idea was 

 actually carried out, and resulted in the invention of his Difference 

 Engine. The engine, so far as it has yet been executed, was constructed 

 at the public expense, and is now deposited in the Museum of King's 

 College, London. The part constructed contains 1 9 digits and 3 orders 

 of differences ; and as all the essential movements are comprised in 

 this part, a more extended engine would consist merely of the same 

 members oftener repeated, and would not involve any additional 

 difficulty of construction. It was part of Mr. Babbage's original 

 design that machinery for printing off the results calculated should 

 be included in his engine, and some of the mechanism for this purpose 

 was actually executed. The portion placed in King's College con- 

 tains machinery for calculating only. It does not fall within the 

 province of this report to do more than mention the Analytical 

 Engine subsequently invented by Mr. Babbage, as the machine of 

 M. Scheutz is a Difference Engine, and nothing more. 



A full account of the principles and action of Mr. Babbage's 

 Difference Engine, but without any details of its mechanism, was 

 published in the ' Edinburgh Review ' for April to July, 1834. It 

 was, as we are informed, the' perusal of this paper which induced 

 M. Scheutz to set about the invention of modes of mechanically 

 executing the necessary changes. The result was the completion of 

 the present engine, which has now for some time been in the apart- 

 ments of the Royal Society. In this machine M. Scheutz has 

 followed the general ideas of Mr. Babbage in the distribution of 

 digits and differences, and in particular in throwing back the dif- 

 ferences at every alternate order one stage, from whence results the 

 possibility of acting simultaneously on all the odd and on all the 

 even differences, and thereby making the machine advance one stage 

 by two addition- motions only; whereas otherwise as many separate 

 addition- motions would have been necessary as there were orders of 

 differences retained. But the mechanism by which the additions 

 and carriages are effected in the machine of M. Scheutz is different 

 from that of Mr. Babbage. The engine is also provided with 



