The Demos II mechanical calculator
Channel: Jaap Scherphuis
Date: 20/11/2019

The Demos II is a rare and unusual calculator. It  uses a toothed segment mechanism and was intended to be a simpler, cheaper alternative to pinwheel machines. It was made from 1923 till about 1926, after which the manufacturers (Moesch und Huber) and distributor (Theo Müggli) switched to making and selling the Direct calculator. It was commercially not very successful.

For more information on this and other calculators in my collection, visit my site:
https://www.jaapsch.net/mechcalc/

0:00 Introduction, History
1:45 Addition
3:37 Multiplication
5:44 Clearing input
6:16 Subtraction
7:35 Division
11:50 Carry mechanism
12:56 Outro