The Calculagraph is a device which mechanically calculates and prints the elapsed time between two events. Their best known, earliest use was as a means of tracking of table usage in

pool hall A billiard hall, also known as a pool hall, snooker hall, pool room or pool parlour, is a place where people get together for playing cue sports such as pool, snooker or carom billiards. Such establishments commonly serve alcohol and often ...

s. Later, until the advent of the

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, they became the standard way to clock the duration of toll telephone calls.

Invention

Henry Abbott, a

watchmaker A watchmaker is an artisan who makes and repairs watches. Since a majority of watches are now factory-made, most modern watchmakers only repair watches. However, originally they were master craftsmen who built watches, including all their par ...

, invented the Calculagraph, and he made a career out of modifying and improving upon the original design. He obtained many

patents A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...

; the first one specifically using the name Calculagraph was No. 583320, issued May 25, 1897. The characteristic aspect of the machine's design is its automatic performance of elapsed-time calculations, as calculating the difference between two times manually is a tedious and error-prone process, and the machines quickly gained popularity. Abbott founded the Calculagraph Company in

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, and later moved to

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. The company is still in business, now known as Control Products, Inc.; however they no longer manufacture the product.

Design

The unit consists of a

clock A clock or chronometer is a device that measures and displays time. The clock is one of the oldest Invention, human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month, a ...

and a precision

gear A gear or gearwheel is a rotating machine part typically used to transmit rotational motion and/or torque by means of a series of teeth that engage with compatible teeth of another gear or other part. The teeth can be integral saliences or ...

-based set of three printing wheels, which print on standardized accounting tickets. One of the wheels presents a clock face, and indicates the time at which a measured interval commenced. It is printed by pushing forward on the right handle. Pulling back on that same handle prints a pair of hollow dial faces with quantities printed around the outside. The ticket is then removed and set aside until the completion event occurs. The ticket is then re-inserted into the Calculagraph, and the left handle is pulled back. This prints a pair of arrow indicators in the center of each previously printed dial, pointing at the elapsed time since the original event. The center of each arrow contains a legend. Models 6 and 110 were based on the original design, and a complete re-design led to the Model 33. The original clocks were wind-up, using the popular Seth Thomas #10 movement. Electric models included 110 V and 20 V versions. Different versions were used as employee time clocks, for professional billing, job cost

accounting Accounting, also known as accountancy, is the process of recording and processing information about economic entity, economic entities, such as businesses and corporations. Accounting measures the results of an organization's economic activit ...

, room and equipment

rental Renting, also known as hiring or letting, is an agreement where a payment is made for the use of a good, service or property owned by another over a fixed period of time. To maintain such an agreement, a rental agreement (or lease) is sign ...

, and many other applications. They could be configured to print in various time formats, such as minutes and seconds, minutes and tenths, or hours and minutes. The pool hall versions printed in dollars and cents. Others printed the date along with the start time. NAWCC Bulletin article which appeared in the February 2001 issue; The Henry Abbott Papers Beth Bisbano, Library Director

References

{{Reflist Telephony equipment Obsolete technologies