1983 Computer Museum of America started its collection with
Frank Stephen Baldwin, 1838-1925, American inventor, began
in 1870 to experiment with the design of mechanical calculators.
The device was patented and marketed in 1875.
The improved 1875 machine initiated the development of the
second fundamental principle in rotary four-rules calculators
which became known as "The Baldwin Principle."
Baldwin developed many more calculators during his life. His
last model was the forerunner of the Monroe machine.
The Monroe Calculator was used extensively in the 1930's.
The Monroe Calculator Company was formed in 1912 and was a
pioneer in electric adding machines. Monroe Calculators are
STILL sold today through Monroe Systems for Business.
Reece Franklin, Computer News of San Diego