Overview

An Appeal to Steam

London, Summer 1821. Charles Babbage (1791-1871), inventor and mathematician, is poring over a set of astronomical tables calculated by hand. Finding error after error he finally exclaims 'I wish to God these calculations had been executed by steam'. His appeal to machinery, in one of the most resonant utterances of the 19th century, was the start of a new era of automatic computation.

The Tables 'Crisis'

It was not only the grindingly tedious labor of verifying a sea of figures that exasperated Babbage, but their daunting unreliability. Engineering, astronomy, construction, finance, banking and insurance depended on printed tables for calculation. Ships navigating by the stars relied on printed tables to find their position at sea. The stakes were high. Capital and life were thought to be at risk.

Infallible Machines

Babbage embarked on an ambitious venture to design and build mechanical calculating engines to eliminate the risk of human error in the production of printed tables. The 'unerring certainty of machinery' would solve the problem of human fallibility. His work on the engines led him from mechanized arithmetic to the entirely new realm of automatic computation. Tabular errors provided a practical stimulus. But this was not his only motive. He also saw his engines as a new technology of mathematics.

Final Vindication

Babbage himself failed to build a complete calculating engine and his designs remained an historical curiosity for over 150 years. Finally, in 2002, the first full-size Babbage Engine (Difference Engine No. 2), built faithfully to the original designs, was completed at the Science Museum in London, the culmination of a seventeen year project. The Engine consists of 8,000 parts, weighs 5 tons and measures eleven feet long and seven feet high. It works as Babbage intended, and brings to a close an anguished chapter in the prehistory of computing.

A duplicate engine is on display and demonstrated at the Computer History Museum in Mountain View, California. It is a sumptuous piece of engineering sculpture and an arresting sight in operation.