Jaap Scherphuis | The O.J. Adder @jaapsch2 | Uploaded August 2023 | Updated October 2024, 1 minute ago.
The O.J. Adder is a simple dial adder for adding British currency. It was made in about 1958-1961. It was invented by Oscar Styles Penn, a man who had quite an interesting life.

For more information about this and other machines in my collection, please visit my website:
jaapsch.net/mechcalc

Picture sources:
Roadless Traction: classicmachinery.net/forum/viewtopic.php?t=11586
Machine gun corps: en.wikipedia.org/wiki/Machine_Gun_Corps
Tank: en.wikipedia.org/wiki/Mark_V_tank

Thanks to Stephen Freeborn for Oscar Penn's death notice.
youtube.com/@stephenfreeborn/videos

0:00 Introduction
0:54 History
3:22 Addition
4:51 Clearing
5:26 Opening the case
5:49 Mechanism
7:00 Outro