Meet The Difference Engine: The World's First Computer

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Sitting in the Science Museum in London is a monster of a machine. The Difference Engine No.2 is the result of a lifetime’s work of brilliant mathematician and inventor Charles Babbage, even though he never saw it come together while he was alive. The machine that sits in the museum today is technically only 13 years old, though it was designed nearly 200 years ago – and the story of how it came to be there is certainly an interesting one.


Businesses up and down the country, indeed across the globe, would have a hard time functioning without the helping hand of computer programs like Microsoft Excel to deal with crucial company data. The ability to calculate complicated sums, reliably and instantaneously over and over again, en masse, is a vital tool that could quite easily be taken for granted in our modern age of electronics; Jim over in Accounts understands.

In the early 1800s, the lack of any such technology was causing headaches for a certain Charles Babbage. The Cambridge-educated mathematician was living in Great Britain in the midst of the Industrial Revolution; the nation was manufacturing, building, developing on an unprecedented scale. The men at the helm of all of this industry – the bankers and architects and navigators and astronomers – were in dire need of reliable and accurate numerical tables to be able to work out complicated calculations, which at the time were still configured and printed at the perilously fallible hands of human beings.

Image credit: Wikimedia Commons/Unknown

Serial-inventor Babbage realised, through experience and great foresight, that this incompatibility between man and machine had to be remedied. His worries are summed up in the now famous 1821 line: “I wish to God these calculations had been executed by steam.” Babbage had been poring over charts of figures with his astronomer friend, and now-legendary scientific figure John Herschel, when he is said to have made the remark. The pen- and ink-drawn tables he held in his hands were chock full of errors that drove him barmy.

From 1821 onwards Babbage worked on designing the first iteration of a machine for crunching precise numbers, the results of which could then be tabulated and produced over and over again. He wanted to revolutionise calculation by mechanising it.

He enlisted the help of Joseph Clement, who was one of the finest toolmakers of his generation, and the two worked together on creating a sort of proof of concept for what he called The Difference Engine, with the help of a £1,700 grant from the government. By 1832 they had come up with what came to be known as ‘the beautiful fragment’, which was a one-seventh section of a potentially much larger fully fledged machine. This hand-cranked device, standing around a metre tall and half as wide, rendered in wonderful brass, is beautiful to behold; at the time it would have seemed nothing short of mind-blowing and today is still seen as one of those important feats of mechanical engineering to come out of the pre-computational age.

By cranking a handle the operator of The Difference Engine fragment started a movement of number-bearing cogs spinning in columns, working to mechanically calculate polynomial sums, which are equations that are made up of more than one mathematical function. It was a marvel of its age. The fragment was toured around the country in a series of lectures by the charmingly named Dionysius Lardner; Babbage would hold dinner parties to show it off, a machine that an eight-year-old or 80-year-old could easily operate.

The beautiful fragment. Image credit: Wikimedia/ Marcin Wichary

Just a couple of years later, while still having spent time and exhaustive money designing the full Difference Engine, Babbage and Clement had a falling out, work was halted and government funding was axed. Babbage spent the next few decades of his life working on a new project, the Analytical Engine, with help from the amazing mathematician Ada Lovelace. The Analytical Engine never made it off the drawing board, though his son Henry P. Babbage did make a section of it after his father’s death. It was an incredible concept of machine for a more general-purpose computation. After those intervening decades, Babbage put the Analytical Engine plans away in and changed tack to work again on a new, improved Difference Engine.

Between 1847 and 1849, Babbage got to work on the blueprints for The Difference Engine No.2. With a more refined design than it could be made with just 8,000 parts as opposed to the Difference Engine No.1’s 25,000; it could, quite incredibly, calculate numbers thirty-one digits long and create tables for polynomials up to seventh order. Despite the improved design, the government shelved plans to put it into production, once again scuppering real success for Babbage’s efforts. After years upon years of dedicated work, none of Babbage’s creations were ever fully realised in his lifetime.

When Babbage died in 1871 so did much of the mechanical computational movement. Modern computing and more precisely computational calculation grew up and evolved without little knowledge of Babbage’s work. By the 1980s, the Babbage family estate had found its way into the possession of the Science Museum in London. The then Curator of Computer at the museum, Doran Swade, alongside a team led by Australian university professor Allen Bromley, unearthed Babbage’s exhaustive plans and worked on building a faithful reconstruction of the Babbage’s Difference Engine No.2.

Seventeen years later, after years of hard toil working off schematics drawn up over 100 years before, the full replica Difference Engine No.2 was debuted in 2002; the main computational portion had actually been finished by 1991, in time for the 200th anniversary of Babbage’s birth, though the printing output section took a little longer. The new Difference Engine No.2, by now often referred to as The Babbage Engine, weighs five tonnes, stands seven-feet-high, eleven-feet-long and 18 inches deep at its narrowest point. In action, still hand-cranked just like the beautiful fragment, it is a symphony of gears, cams, rods and levers; columns bearing steel fingers rotate in symmetrical harmony to fetch their number-bearing cogs and click them into place, before making an impression of the result on paper, as well as pressed into a kind of plaster sheet, which once set, produces reams of mechanically worked-out digits.

The replica Difference Engine No.2 in action. Video credit: Wikimedia/ Wolff Dobson]

It is practically hypnotic to see in action, and truly incredible to think how long ago it was thought up, predominantly in the mind of one man. It is a great shame that Babbage could never see his baby in action, but a real treat that we are able to witness such an incredible machine today.

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Featured image credit: Wikimedia/Martin Wichary