Mechanical calculator

A machine that performs arithmetic through moving mechanical parts such as gears, wheels, and levers. Its mechanisms encode numbers and carry out operations without electronic computation.

Gear train: A set of meshing gears that transmits motion and changes speed, direction, or torque. Interlocking gears transmit digit changes and coordinate arithmetic operations.
Abacus: A manual calculating instrument that represents numbers with movable counters or beads. It is a major premechanical approach to representing and manipulating numbers.
Comptometer: A key-driven mechanical calculator that performs addition and subtraction through direct entry. Its fast keystroke entry made it useful for high-volume office arithmetic.
Electronic calculator: A device that performs arithmetic using electronic circuits. Electronic circuits replaced moving arithmetic mechanisms with faster, quieter computation.
Odometer: A device that records distance by advancing numbered wheels as a wheel or axle turns. Its wheels demonstrate how a mechanical carry advances one digit when another completes a cycle.
Pascaline: A mechanical adding machine designed by Blaise Pascal in the 1640s. Its linked numeral wheels and carry mechanism established an influential calculator design.
Arithmometer: A nineteenth-century mechanical calculator that became the first commercially successful calculator made in quantity. Its widespread production brought mechanical calculation into offices and institutions.
Slide rule: A manual analog instrument that uses logarithmic scales to perform multiplication, division, and related calculations. It provides a portable alternative but generally gives approximate rather than exact results.
Stepped drum: A cylinder with steps of increasing length, used to engage different numbers of gear teeth. Leibniz calculators used its stepped geometry to encode repeated addition and multiplication.
Stepped Reckoner: A mechanical calculator designed by Gottfried Wilhelm Leibniz to perform addition, subtraction, multiplication, and division. Its stepped drum extended mechanical calculation beyond simple addition and subtraction.

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