Uploaded April 2019 | Updated September 2026, 2 hours ago

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This mechanical calculator, or adding machine, is the Conto, model C.

It was made in Thalwil, near Zürich in Switzerland, from 1914 until about 1932. Probably only about 2000 were made, or 3000 if you include the models A and B.

For more information about the Conto and other mechanical calculators in my collection, visit my web site:
jaapsch.net/mechcalc

0:00 Introduction
0:53 Addition
1:52 Clearing
2:06 Seal
3:05 History
4:32 Opening the case
5:17 Outro