|"Dorr E. Felt began working on what would become the Comptometer in
1885, making the first working version in metal in 1886 (the 1885 model was made mostly of
wood and spare parts), and began low volume production by hand in 1887. Felt went into
partnership with Robert Tarrant to produce and refine the Comptometer over many years.
Although rather common due to their relatively high production, the Comptometer is an
historically significant machine, being the first successful multiple order key driven
calculator. Felt's new carrying mechanism was complex, but it met the high speed
requirement of a key driven calculator. The 8 column Comptometer could add faster than an
accountant's brain, which was its key to success."
Richard Van Vleck - Scientific Medical & Mechanical Antique
"The wooden case model...
Serials below 15,000, altho there have been none discovered
above 6121. This was, of course, the simplest model and was produced from 1887 thru 1903.
The very earliest examples are on display at the Smithsonian Museum in Washington, D.C.
and have no serial numbers. The lowest known "serialized" machine is 136 and, as
of April 1999, was up for auction.
Brooke W. Boering (aka Vagabondo) - The Comptometer Memorial Website
Photo Source: The Comptometer Memorial Website