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I. The Defcription andXXk of an Arithmetical 
Machine invented by Chriftian-Ludovicus 
Gerften, K % S. Trofeffor of Mathematic ks 
in the UniVerjity of GiejOfen. Infcribed to 
Sir Hans Sloane, Bart. < Vrejldent of the 
Royal Society. [See Tab. Fig. 1,233,4,5.] 
SIR, 
B EING at prefent on the Point of returning 
Home, I think myfelf obliged before my 
Departure, to return my humble Thanks to 
that Learned Body the Royal Society , over which 
you prefide, for the Honour they have lately done 
me, in chufing me a Member ; and to make a 
grateful Acknowledgment to you in particular, 
for the many Favours and Civilities, which, accord- 
ing to that amiable Character of Benevolence to all 
Strangers in general, you have been pleafed to be- 
llow on me. 
It is now a Duty incumbent on me to communi- 
cate to the Royal Society from time to time any 
thing new and curious, which may fall in my way : 
Therefore I now lay before them a Draught and De- 
fcription of an Arithmetical Machine, which I in- 
vented about twelve or thirteen Years ago. 
Sir Samuel Morland was, for ought I know, the 
firft who undertook to perform Arithmetical Opera- 
tions by Wheel-work. To this end he invented 
two different Machines, one for Addition and Sub - 
JlraSlion , the other for Multiplication , which he 
publilhed in London , in the Year 1 673, in J mail 
L Twelves . 
