Charles Babbage (1792-1871), British mathematician and inventor designed two prototype mechanical computers, but failed to complete either during his lifetime. He presented the Difference Engine to the Royal Astronomical Society in 1821. The two and a half metre high first version, weighing 15 tons, consisted of 25 thousand parts. The second one, which (in theory) also included a printing mechanism, only existed in drawings.

It was built between 1989 and 1991, and did the first calculations with results of 31 digits at the London Science Museum.

After the failure of the Difference Engine, Babbage embarked on the design of a more complex machine, the Analytical Engine, on which he worked until his death. It primarily differed from its predecessor by being programmable with the help of punched cards. It was never completed, although one of the few to understand the inventor’s ideas, Ada Lovelace (1815-1852), Lord Byron’s daughter, wrote programme for it.

Regarded to be the forerunner of computers, the Analytical Engine was able to store programmes, use conditional branching, and had addressable memory. It was never constructed for two reasons: on the one hand solutions to friction and transfer were not adequate at the time, and constant vibration also posed a serious problem. On the other hand, Babbage made changes to the original plans while the machine was being constructed.

It is little known that his youngest son, Henry Provost Babbage (1824-1918) built a part of the machine on the basis of his father’s drawings, and the machine passed the first “test” by computing multiples of pi on 21 January 1888. This is likely to be the first test passed by a portion of a modern computer. A part of the machine constructed by the younger Babbage was recently auctioned at Christie’s, and bought by a museum in Sydney.