How to use the de Colmar Arithmometer: Addition, Subtraction, Multiplication, and Division Demo

A demonstration of how to do the 4 main arithmetic methods on the de Colmar Arithmometer. This machine is the 1865 design, manufactured in 1876

[@cigdemturkmen]

Oh. My. God. Cant believe how far we have come

[@abcstardust]

A quick question if I can: I notice 4 screws on the inner wall above be the counting shafts. They each have a hole corresponding to them on the front of the machine. Do you know what they’re for?

[@abcstardust]

How long is your machine?

[@abcstardust]

One question if I may: What size are the Leibniz wheels?

[@bss1250]

Its been a few months since I worked on this but I think they were about 1inch in diameter by 2 inches long

[@abcstardust]

Thank you very much bss

[@MattMcIrvin]

That strange "absolute value of net additions" behavior of the counters is something you don't see often in mechanical calculators--I guess it removes the need for another switch to reverse the counters so you can do either multiplication or division.

[@abcstardust]

The reason I asked was because the price of buying one is prohibitive for me; so I’m going to attempt to actually build one for myself. So any help you can give me I appreciate. But I promise not to hound you about it lol

[@bss1250]

Sorry Im not always great about responding to comments on time… the wood case is 18 1/4 inches long, the carriage is 17 1/4 inches long, and the main body of the machine is 11 3/4 inches

[@abcstardust]

Thank you Bss!