My Slide Rule Collection

Adding Machines

Also known as Troncets after their French inventor, or Slide Adders, or Arithmometers, or ... they've got lots of names.

Tasco Pocket Arithmometer

This is a very nice machine, made by Reliable Typewriter & Adding Machine Corp, of Chicago, Illinois. Subtraction is performed by sliding the lower template up to cover the addition template.


What a strange name. Made by Reliable Typewrite & Adding Machine Corp, Chicago, Illinois. They're glued into little leather-and-cardboard flip-cases, with a pocket on the side for the stylus. As you can see, I have two of them.

SH Pocket Calculator

Plastic and aluminum, almost a toy. (In fact, I had one very much like this as a child.) This is basically a relabeled "Magic Brain" calculator.

Addimult Sumat 6

Made in West Germany and imported.

Arithma Addiator

The Arithma Addiator is probably the most famous adding maching of them all. This one is stuck to the back of a Keuffel & Esser 4097D slide rule.

Sterling No. 565 Dial-A-Matic Automatic Adding Machine

Unlike the others, this machine uses dials instead of slides. It had no clearing mechanism. Made by the same company as the Sterling slide rules.

Sterling No. ??? Dial-A-Matic Automatic Adding Machine

Another Sterling Dial-A-Matic, this one with six digits and a clearing lever. It appears that it did not, however, come with a stylus, as I can't find a stylus mentioned anywhere on the box. Anyone know what model number this one is?


This one also uses wheels. I know nothing about this machine at all. It's actually quite small, about 5" x 8".



© 2003 W. E. Johns