Pascal Adding Machine Section (Replica)

As a youth, Blaise Pascal (1623-1662) was asked to assist his father in calculations relating to tax returns. Pascal, a future mathematician and natural philosopher, decided that addition and subtraction could be done more easily by machine. The French teenager invented one of the first mechanical adding machines. This is a replica of two counting units in a Pascal adding machine.

The model has a brass mechanism, paper number labels, and a transparent plastic case. It shows the two highest counting units of a Pascal adding machine. Two wheels at the front are for entering digits. They both link to horizontal cog wheels with pins protruding from them. These wheels, in turn, are linked to vertical cog wheels that drive the result drums at the back. The vertical wheels are also linked so that as the wheel on the right advances, a weight linked to the other wheel rises. Once the right wheel has been turned a full circle (entering 10), the weight falls and advances the left wheel by one unit, carrying a digit. Nines complements are marked around the result dials for use in subtraction.

Pascal and his associates made about fifty adding machines in the course of his life, but they never became a practical product. This replica was made for the Smithsonian in 1964.

Reference:

Michael R. Williams, A History of Computing Technology, Englewood Cliffs, N.J.: Prentice-Hall, 1985.

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