M. Le Colonel D’Ocagne, Ingénieur des Ponts et Chaussées, Professeur à
l’École des Ponts et Chaussées, Répétiteur à l’École Polytechnique, in
his “Le Calcul simplifie,” a historical review of calculating devices
and machines, refers to the key-driven machine as having first made its
appearance in the Schilt machine of 1851, but that the Art reached its
truly practical form in America. In the latter part of his statement
the professor is correct, but as to the first appearance of the
key-driven machine the U. S. Patent Office records show that a patent
was issued to D. D. Parmelee in 1850 for a key-driven adding machine
(see illustration).