Manual Calculators
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Operation

Manual Calculators

This group of machine are calculating machines comprising all non-printing (listing) machines. Typically called Key Driven Calculators at Burroughs.

The first machines of this type were built by Dorr E. Felt, marketed by the Felt and Tarrant Manufacturing Company for many years.  Called the Comptometer by Felt, Burroughs referred to this type machine as the key-driven calculator.

The key-driven type machine did not print, and while it was often used as an adding machine, it developed into a special purpose machine in later years.  The machine was exceedingly fast and experienced operators could easily outrun an operator on a full keyboard or 10-key adding machine.  The efficient operation of these machines required an experienced operator who often received a high salary.

The machine was produced over a very long period because of its unique capabilities and was most often used to verify product delivery lists from delivery routes, such as home dairy delivery, where extending totals was a repetitive task. Later models of the machine, called a duplex design, could hold a running total in a second set of dial wheels while the primary wheels continued to add and subtotal amounts that could be transferred at any time to the running total.

A side note, Burroughs copied the Felt design for its first models and was sued for patent infringement by Felt and Tarrant who prevailed in the suit.  As a result, Burroughs totally redesigned their machine and went on to compete with the Felt machine for decades.

Class 5 (Shoebox square-corner design) – Key-driven, non-listing (no printer), calculating machine with single register (simplex). Called the "Box Type" 

Date Range -- 1911-1914 

Original Price -- $200-$300

Today’s Value -- $75-$200

 

Old construction - rare

Front view - note the old style lettering

Nice picture with instruction manual

Class 5 (round corner design) – Non-listing, key-driven, calculating machines with single register (simplex). In later years they were identified as the Series C machines.

Date Range -- 1915-197x

Original Price -- $200-$300

Today’s Value -- $50-$150

Very narrow machine - actually quite popular

Most were hand operated for clearing

Position was everything, here are the extension legs often used.

Class 5 Electric – Non-listing, key-driven, calculating machines with electric key-actuation and clearing. These machines include both simplex (one register) and later duplex (two register machines). Additionally, a simplified subtract method was introduced on the simplex electric machines in 1936. 

Date Range -- 1928-197x

Original Price -- $200-$300

Today’s Value -- $50-$150

 

This model was power operated, both the keys and the clearing. This specific machine also included a simplified subtraction capability (see red keys in front part of keyboard)

 

Class 5 Duplex – Non-listing, key-driven, calculating machines with two registers. In later years they were identified as the Series C machines. This model was the first direct subtraction model (introduced in 1937).

Date Range -- 1933-197x

Original Price -- $400

Today’s Value -- $100-$200

 

Style 51055 (Calculator, 10 columns, 5 power, 5 duplex)

Newer machine, about 1955