Fig. – First Difference Engine. This impression from a woodcut was printed in 1853 showing a portion of the Difference Engine that was built in 1833 by Charles Babbage, an English mathematician, philosopher, inventor, and mechanical engineer who originated the concept of a programmable computer.
“If all you have is a hammer, everything looks like to you as a nail” ~ Abraham Maslow, in “The Psychology of Science“, 1966.
“Propose to an Englishman any principle, or any instrument, however admirable, and you will observe that the whole effort of the English mind is directed to find a difficulty, a defect, or an impossibility in it. If you speak to him of a machine for peeling a potato, he will pronounce it impossible: if you peel a potato with it before his eyes, he will declare it useless, because it will not slice a pineapple. […] Impart the same principle or show the same machine to an American or to one of our Colonists, and you will observe that the whole effort of his mind is to find some new application of the principle, some new use for the instrument“. ~ Charles Babbage quoted in Richard H. Babbage (1948), “The Work of Charles Babbage“, Annals of the Computation Laboratory of Harvard University, vol. 16.
At the beginning of the 1820’s, Babbage worked on a prototype of his first difference engine. Some parts of this prototype still survive in the Museum of the history of science in Oxford. This prototype evolved into the “first difference engine.” It remained unfinished and the completed fragment is located at the Museum of Science in London. This first difference engine would have been composed of around 25.000 parts, weighed around fourteen tons (13.600 kg), being 2.4 meters tall. Although it was never completed. He later designed an improved version, “Difference Engine No. 2”, which was not constructed until 1989–91, using Babbage‘s plans and 19th century manufacturing tolerances. It performed its first calculation at the London Science Museum returning results to 31 digits, far more than the average modern pocket calculator. (check Charles Babbage Wikipedia entry for more).
Soon after the attempt at making the difference engine crumbled, Babbage started designing a different, more complex machine called the Analytical Engine (fig. above). The engine is not a single physical machine but a succession of designs that he tinkered with until his death in 1871. The main difference between the two engines is that the Analytical Engine could be programmed using punched cards. He realized that programs could be put on these cards so the person had only to create the program initially, and then put the cards in the machine and let it run. It wasn’t until 100 years later that computers came into existence, with Babbage‘s work lying mostly ignored. In the late 1930s and 1940s, starting with Alan Turing‘s 1936 paper “On Computable Numbers, with an Application to the Entscheidungsproblem” (image below) teams in the US and UK began to build workable computers by, essentially, rediscovering what Babbage had seen a century before. Babbage had anticipated the impact of his Engine when he wrote in his memoirs: “As soon as an Analytical Engine exists, it will necessarily guide the future course of science.“