18 Mr. J. Edmondson on Calculating Machines. 



limited, and there are other defects inherent in the method of 

 its construction. 



Still more recently Mr. Tate, of London, has introduced a 

 machine on the lines of M. Thomas, in the internal mechanism 

 of which there are several improvements. The workmanship, 

 too, is very superior to that of the French instrument. 



Mr. Edmondson (the lecturer) having, in practice, found 

 certain inconvenient limits to the utility of these machines, 

 conceived the idea of obviating them by throwing the instru- 

 ment into the circular form, and thus obtaining an endless 

 instead of a limited slide. This has produced a machine of 

 greatly extended powers ; for it can deal with a multiplier or 

 dividend of any number of figures, and can carry a quotient 

 to any number of decimal places. But its chief utility does 

 not consist in dealing with such large numbers. It frequently 

 happens that quotients produced on a machine require to be 

 further operated upon ; but as in the straight machines they 

 are recorded on a special set of dials, which are not in the 

 general working line, they must be transferred by hand before 

 tluy can be dealt with in any other way than as multipliers. 

 In the circular machine they come up in the working line 

 ready for further operations. The circular form, in fact, 

 gives a certain elasticity in the applications of the machine 

 which could not be described within the limits of the lecture, 

 and which can only be appreciated by actual use of the in- 

 strument. Although the special set of dials for recording 

 multipliers and quotients are dispensed with as non-essential 

 in the circular machine, they could be easily and conveniently 

 added, and would still further extend the powers of the 

 instrument. 



The lecturer expressed his indebtedness to the following 

 gentlemen for the loan of valuable instruments on the table, 

 which, along with Mr. Tate's machine and several belonging 

 to the lecturer himself, attracted much attention after the 

 lecture : — 



Genera] Babbage, Bromley, Kent. A piece of the Differ- 

 ence- Klngine of the late Charles Babbage, Esq. ; Stanhope 

 Machines of 1775 and 1777 ; Sir Samuel Moreland's Machine 

 of 1663. 



The Rev, Professor Harlev, F.R.S., Huddersfield. Stanhope 

 Machine of 1780. 



Theodore B. Jones, Esq., Harrogate. The American 

 Machine of George 1>. Ghcant, Esq. 



F. H. Bowman, Esq., D.Sc, Halifax. A Machine of Sir 

 Samuel Morelaiufs, constructed on the principle of ''Napier's 

 Bones/' 



