The Unitas Calculator
Channel: Jaap Scherphuis
Date: 2018-08-07

The Unitas is a mechanical calculator based on the Arithmometer of Thomas de Colmar. Its unique feature is that it has two output registers, each on its own movable carriage. It was made by Ludwig Spitz & Co in around 1912.

For more information about this machine and other calculators in my collection, see my website:
https://www.jaapsch.net/mechcalc/

0:00 Introduction, history
1:38 Addition
2:12 Multiplication
2:36 Subtraction
3:02 Clearing
4:01 Item counting
5:02 Second register
6:35 Disassembly
7:49 Serial numbers
9:05 Stepped drum mechanism
10:20 Carry mechanism
11:31 Direction switch
12:39 Overflow bell
13:20 Flow
14:22 Outro