# Pascal's Calculator (Algebra and Arithmetic Plate II)

This plate combines the Encyclopédie’s depiction of the mechanical arts with its descriptions of mathematical and scientific theories. At the age of nineteen, Blaise Pascal developed the first practical mechanical calculator in 1642 to assist with his father’s tax collections. Pascal is perhaps most well known for developing the theory of probability, studying atmospheric pressure, and theology. This illustration depicts the entirely mechanical nature of the calculator, relying on a series of gears to carry out addition, subtraction, multiplication, and division. Diderot dedicates four pages of the Arithmetic entry to describing the complex operation of Pascal’s calculator. Despite this description, the precise method by which subtraction was implemented and the overall accuracy of the device have remained contentious. His contribution to science and computation is evident in the Pascal SI unit of pressure and the Pascal programming language.

Denis Diderot (1713-1784)

Encyclopédie. Volume 5, Science – Mathematics – Algebra (Sciences – Mathématiques – Algèbre) Plate II: Pascal's Calculator.

Paris: Briasson [etc.], 1751-1772