In the early 1800s, a ship’s navigator used a sextant to measure sightlines to the Sun, Moon, and other celestial bodies and, with the assistance of nautical tables, computed the ship’s position. Unfortunately, the numerical values in the tables had been prepared using the finest technology available at the time, which consisted of humans working through tedious calculations by hand. Because of this, the tables were riddled with errors, which could easily lead to catastrophe for a ship at sea.
In 1820, Charles Babbage, as a founding member of the Astronomical Society of London, undertook to improve the accuracy of nautical tables. Babbage came to believe it would be possible to construct a machine capable of computing the numeric values for the tables and printing the results. His proposal to develop a machine called the Difference Engine for this purpose led to an effort that terminated after ten years without producing a working apparatus.