More than 150 years ago, the English mathematician, inventor, philosopher and reformer Charles Babbage designed a general-purpose mechanical calculating machine that anticipated the principles and structure of the modern computer.

In 1823 Babbage started working on his Difference Engine No1, a fully automatic machine that calculated and printed the tables used in the burgeoning fields of science, navigation and business. His aim was to relieve people of 'routine mental labour' and eliminate human error in calculations with a perfect machine.

The Difference Engine was designed to produce successive values of a polynomial function using the Method of Finite Differences. This method reduced the calculation to a series of additions. Once the initial values were entered into the machine the operator need only to turn the handle to generate the tables. Most significantly, the operator didn't need to know any mathematics.

Babbage worked on the Difference Engine No1 for 11 years but was never able to complete it. There are a number of factors that contributed to his failure including the strain and expense of having to develop new manufacturing machining techniques, personality clashes especially with his engineer, the death of his wife and several of his children and the general lack of understanding of his project.

He was perhaps also distracted by his conception for a more ambitious machine, the Analytical Engine, a machine capable of finding values for any algebraic function. Like the modern computer, it was to be a general purpose, programmable machine in which the storage of information was a separate function to the processing of information. The Analytical Engine was never built and the ideas he developed had to wait another 100 years to be "rediscovered".

While Babbage did not successfully complete any of his engines, his efforts had profound impact in other ways, particularly in the "mechanical arts" and on the organisation of manufacturing processes.

In 1879 Charles Babbage's son Henry assembled this portion of the Difference Engine from original parts after his father's death. It was one of six specimens constructed to demonstrate the addition and carry mechanism.