Babbage’s Difference Machine lecture 14 June 1822

On this day in 1822, Charles Babbage proposed a ‘Difference Machine’ in a lecture to the Royal Astronomical Society of London, ‘Note on the Application of Machinery to the Computation of Astronomical and Mathematical Tables’*

His difference engine is a mechanical calculator that evaluates polynomial functions. The name comes from the method of divided differences, a way to interpolate functions by using a small set of polynomial coefficients. Most mathematical functions commonly used by engineers, scientists and navigators, can be approximated by polynomials. A difference engine can, therefore, compute many useful tables of numbers. Babbage is credited with the concept of a digital, programmable computer.

Babbage Quotation:

The errors which arise from the absence of facts are far more numerous and more durable than those which result from unsound reasoning respecting true data**. 

*This is the title from the Memoirs, or as we would say today Proceeding, of the Royal Astronomical Society. Later Babbage published the abstract of his talk in a book and used the title, ‘A Note Respecting the Application of Machinery to the Calculation of Astronomical Tables’.

**C. Babbage, ‘Of Price as Measured by Money’, On the Economy of Machinery and Manufactures (1st ed., 1832), chap. 17, 112.