Charles Babbage and His Inventions

An eccentric mathematician and a genius, Charles Babbage was a prolific inventor, whose inventions included the ophthalmoscope (for examining the retina of the eye), the skeleton key, the locomotive " cow catcher", and the speedometer. He also pioneered operations research, the science of carrying out business and industrial operations as efficiently as possible. Babbage was a fellow of the Royal Society, and at Cambridge University he held the same chair that was once held by Isaac Newton, the most famous of British scientists.

The mathematical tables of the 19^th century were full of mistakes. Even when the tables were calculated correctly, the printed versions often contained typographical errors. Because people who published new tables often copied old ones, the same errors cropped up in table after table.

Babbage set out to build a machine that would not only calculate, but would also automatically print. He called the machine the Difference Engine because it worked by solving what mathematicians call " difference equations". The name is somewhat misleading in that the machine constructs tables using repeated additions, not subtractions.

However, struck by a much better idea Babbage abandoned the Difference Engine. He wanted to build a punched-card-controlled calculator. He called his proposed automatic calculator the Analytical Engine.

The Difference Engine could compute only tables. But the Analytical Engine could carry out any calculation. All a person had to do was punch the cards with instructions for the desired calculations.

The Analytical Engine had many of the major components found in modern computers. Babbage referred to the machine's main memory as " the store"; the terms " store" and " storage" are still sometimes used to trier to main memory. The Analytical Engine's central processing unit consisted of " the mill", which carried out arithmetical calculations, and the barrel", which actuated the parts of the machine needed to carry out each instruction. Today we would call the mill the arithmetic/logic unit and the barrel the control unit. Input data for the Analytical Engine was on punched cards, and its output was printed on paper.

Had the Analytical Engine been completed, it would have been a 19^th century computer. But alas, that was not to be. The British Government had already sunk thousands of pounds into the Difference Engine and had received nothing in return. It had no intention of making the same mistake with the Analytical Engine. No working Analytical Engine was ever built,

and Babbage's work was forgotten until after the same discoveries had been made independently by the computer pioneers of the 20^th century.