| Comptometers |
8 Column Comptometer
|
Dorr E. Felt of Chicago created the first
comptometer (1885) using an old macaroni box at the age of twenty-two.
The Comptometer is claimed to be the first successful keyboard adding
machine on the market. It is a portable, full keyboard, direct key driven
machine designed for high speed calculations involving all branches of
mathematics. It is duplex in operation in that it will add in more than
one column at a time, each column having the capacity to add, receive,
and carry simultaneously. Totals are shown in dials below keyboard;
denominational readings are facilitated by dial wheels of two colors, and
by decimal markers; there is no printing mechanism. Dials are reset by a
clearing lever at side of the machine. The keyboard design offers good
feedback, and the operation is quiet compared to some of the clinkier
models.
Later enhancements to the machine included the addition of the multiplex
keys, which permit simultaneous depression of keys in several different
columns. Additionally, the triple-clear signal was added to eliminate
the danger of the machine not being set to zero before beginning a new
operation. As soon as a new operation is commenced, the operator will be
reminded by the sound of a bell. If only half-zeros appear in the
windows and the operator feels a slight resistance, the machine has been
properly set to zero.
Depending on the model, Comptometers generally ranged in weight from
17 1/4 pounds to 24 1/4 pounds, and could be purchased for $300 -
$400. |
