Discovery of a Lost Factoring Machine

J. Shallit, H. C. Williams and F. Morain

Eugène Olivier Carissan, inventor of the "machine à congruences".

Photo courtesy France Silber.

In this picture, we see the Carissan machine with its congruence rings removed.

Photo courtesy Francois Morain.

In this picture, we see the Carissan machine "programmed" up to solve a problem. The armature, which detects solutions, has been removed.

Photo courtesy Francois Morain.

Here the armature has been restored.

Photo courtesy Francois Morain.