The 1840's were a turning point in the history of mechanical calculation. The development of science and technology, commerce, banking and insurance created major calculating needs. At the Exposition Nationale in 1844, several brilliant inventors were in competition with each other: Thomas de Colmar, Dr Roth, Maurel and Jayet ! Dr Roth was a multi-faceted person. Doctor in homeopathy and a great lover of the arts, he invented a whole series of instruments and calculating machines in only a few years. His hand-written patents amount to nearly 80 pages! It is time to pay homage to the inventor.This is a contribution / VM