Charles Babbage was the quintessential "man ahead of his time". In the mid 19th century the English mathematician and inventor developed the concept of a programmable computer and designed complex, steam-powered calculating engines that were never completed during his lifetime. One of these machines – the Difference Engine – was successfully constructed using Babbage's original plans in 1991 and now programmer John Graham-Cumming is on a mission to build a working replica of a second, more complex computing machine known as the Analytical Engine.

Babbage invented the first Difference Engine in 1821. Designed to perform mathematical calculations, the machine would have been made up of 25,000 parts, weighed 15 tons and stretched to 8 ft in height – so portable isn't a word that would apply. Babbage worked on a prototype which was never completed, but some parts of his early attempts to construct the machine survived and are on display at the Museum of Science in London.

Swedish printer George Scheutz did manage to successfully construct a machine based on the Difference Engine in 1854. It was used used by the British and American governments to print mathematical and astronomical tables.

Difference Engine No. 2

Difference Engine No. 2 was an update on the original design which Babbage worked on, but never built, between 1847 and 1849. This is the machine which was reconstructed by the
London Science Museum using the original plans between 1985 and 1991. It weighs 3 tonnes, has over 4000 parts and it
works, performing astonishing calculations to 31 digits. The printer for the Difference Engine – a lightweight at 2.5 tons – was built in 2000.

The Analytical Engine

Back to the Analytical Engine – the focus of Graham-Cumming's new campaign to pay tribute to the genius of Babbage. Early designs for the Analytical Engine appeared in 1835, but Babbage continued to refine the idea until his death in 1871. The Analytical Engine is credited as being the first example of a general purpose computer and was conceived as a multi-functional machine that could perform different types of calculations. The machine would have been programmable by punch cards and its two main parts – the "mill" and the "store" – are the precursors of what we know as today as CPU and memory.

If the Difference Engine is a calculator, the Analytical Engine is a computer, so the challenge of building the machine is a truly formidable one. Babbage envisioned it as being constructed from brass and iron and it would be monstrous – the mill section would be 15 feet tall and 6 feet in diameter and the 100 digit store would stretch to 25 feet long.

Five hundred design drawings and thousands of notes were produced by Babbage and his assistants and although he spent a fortune trying to build it, the machine was never realized.

An interesting footnote here – Ada Lovelace, who is considered to be the world's first computer programmer, collaborated with Babbage on creating execution tables for these early computing machines.

Building the world's first computer

Graham-Cumming is hoping to raise £400,000 to complete a working model of the Engine from the original blueprints. The goals of the non-profit venture are to first digitize Babbage's notes, study the plans to establish a complete design and then build a 3D computer simulation before embarking upon the building process. The finished model would be donated to a museum in Great Britain for public display

Graham-Cunning reports on his blog that in under two weeks the Analytical Engine PledgeBank has received over 2,700 signatories with pledges of up to $1000. Promises of design and manufacturing support have also been received and the project has the support of the descendants of Charles Babbage.

Fascinating stuff! We wish the project every success. If you would like to contribute, visit the Analytical Engine PledgeBank.

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