Thomas de Colmar is best known for his sophisticated mechanism designed to realize all four arithmetic operations, which was marketed in machines called Arithmometre. However, like many other designers before him, Thomas also explored the basic mechanisms of arithmetics using simpler designs.
In the animation created by Ms. Lippmann and Mr. Vellmer as part of their bachelor's thesis, one such design by Thomas based on his 1849 patent has already been illustrated.

In order to understand the considerations that occupied a designer like Thomas in the basic design and the detailed design of such mechanisms, it is useful to compare different models. We will therefore now look at another version of an adding machine by Thomas, which was presumably also made around 1850. Externally, the input mechanism with its distinctive star engravings is clearly similar. However, the internal structure shows some differences and sheds light on the multifaceted design decisions that an inventor had to make even for parts of basic functionalities. Take a look under the top plate of both machines with us and discover it for yourself. In this video created by Kai Becher, the mechanics of this calculating machine are visualized and explained in detail.