Adding Machine Sales Company Addometer
Frank Baldwin based his calculating machine on the invention
of Gottfried Leibniz, the German mathematician and philosopher
who used a collection of pinwheels and stepped cylinders containing
ridge-like teeth of different lengths corresponding to the
digits 1 through 9. Baldwin replaced Leibniz's cylinders with
a single cylinder with a variable number of teeth (1 through
9) protruding according to the motion of the setting lever.
This evolved into the machines you see here which use a stylus
to turn the wheels like a telephone dial.
Donor: Jim & Marie Petroff