Long before the advent of practical electronics or digital devices, one man conceived the idea of a multi-purpose machine capable of performing a wide range of calculations and tasks. Charles Babbage, the British scientist and mathematician, was a man ahead of his time.

Charles Babbage was born on Boxing Day, 1791, the son of a partner in an English banking company. A sickly child, who survived a life-threatening fever at the age of eight, Babbage was mostly educated by tutors at home before going up to Cambridge University in 1810 to further his already great interest in mathematics having taught himself algebra as a young child. He would become a highly-regarded academic mathematician who was elected Fellow of the Royal Society at the age of 25 and in 1828 was awarded the Lucasian Chair of Mathematics at Cambridge, a highly prestigious position that had been previously held by Sir Isaac Newton and would later be held by Stephen Hawking.

Whilst at Cambridge, Babbage became close friends with fellow student (and future astronomer and photo-chemist) John Herschel. The pair, along with other students, founded the Analytical Society in 1814 and were also involved in the formation of the influential Royal Astronomical Society in 1820. It may have been Herschel who prompted Babbage towards his pioneering work towards computers.

For over 2000 years, the abacus had remained the only reliable mechanical means of calculating by machine. As industry and science advanced in the 17^{th} and 18^{th} centuries, a handful of simple mechanical calculators were built by scientists including Gottfried Liebnitz and Blaise Pascal. For anything more complex, giant volumes of printed mathematical tables were used to make advanced calculations. These were produced by hand by dozens of clerks known as “computers” and were extremely important in engineering, science and navigation by shipping. However, using the published tables could be painfully slow and extremely frustrating as the tables were often full of errors. A contemporary of Babbage’s, Dionysius Lardner, surveyed 40 volumes of tables and found 3,700 known errors and assumed many more could be present.

Babbage was an avid collector of these mathematical tables and recalled in 1839, a key moment when John Herschel brought him a new volume many years earlier.

*Mr. Herschel…brought with him the calculations of the computers, and we commenced the tedious process of verification. After a time many discrepancies occurred, and at one point these discordances were so numerous that I exclaimed, “I wish to God these calculations had been executed by steam.”*

Babbage began thinking seriously of ways that complex calculations could be performed by innovative, new machines. This may seem obvious to us, but at that time many forms of technology was still very much in their infancy. Scheduled passenger steam train services had yet to run, there was no practical photography and electricity remained a scientific curiosity with the very first electric motors and generators only created by Michael Faraday in the 1820s.

By that time, Babbage had had his 1823 proposal for a giant machine to produce accurate mathematical tables accepted by the British government who made a grant of £1,700 which would rise to around £17,500 by 1833 – a large sum equivalent to several million pounds today. In addition, Babbage’s father died in 1827 leaving him a fortune estimated at around £100,000, much of which he also used on his machines. Babbage’s first Difference Engine design, if completed, would have become one of, if not, the world’s most complex machines of his age. It would have stood 2.4m tall, weighed in excess of 10 tonnes and included its own automatic printer so that no human error could enter the process between calculating and printing the tables on paper.

It was designed to consist of a large row of vertical shafts each bearing many toothed brass gear wheels. Each digit of a number to be computed was represented by one of the gear wheels and the mechanism worked by the method of finite differences so that complex calculations could be achieved through large quantities of different addition sums.

Babbage’s plans were extraordinary but they called on an incredibly high level of accuracy in the manufacture of the engine’s 25,000 parts. Using electricity was out of the question and the hand-powered mechanical machine needed perfect precision for friction not to slow or stop the workings of its vast array of components. This proved an undertaking that no engineering contractor could manage sufficiently. Years passed, costs mounted and tensions grew. Thousands of parts were produced and later melted down for scrap. Babbage would later design a smaller Difference Engine No.2 requiring fewer parts, but by the early-to-mid-1830s, his attentions had turned to something far more ambitious.

Babbage’s Analytical Engine was truly revolutionary. It was to be a device which could perform direct multiplication and division as well as addition and subtraction and be programmable in order to produce any conceivable calculation. It used the crucial concept of separating data and instructions as well as the idea of punched cards (borrowed from card-operated weaving looms) to provide programs and subroutines for the Engine. It also offered a variety of different output options including graph plotting, hardcopy printouts and stereotypes – trays of soft material which could be impressed with tables of numbers and then used as a mold for the plates of printing presses.

Central to the Analytical Engine’s workings was its memory called a, “Store” where numbers and intermediate results of calculations could be held. Babbage planned the Store to hold up to one thousand 50 digit long numbers but be expandable, using punched cards as an output which could then be returned to the machine.

The Store was separate from the engine’s “Mill” where the arithmetic processing was performed, similar to the central processing unit of an electronic computer. Babbage’s device was planned to support various advanced functions found in today’s digital devices including conditional branching, looping and parallel processing. In short, it contained, in principle, many of the key parts, functions and division of tasks found in digital computers. There had been nothing remotely like it before.

Whilst Babbage constructed detailed plans and notes on the Analytical Engine, he was unable to complete a physical version of his machine. He died in 1871 having previously accepted gloomily that, “another age must be the judge”. His son, Henry Provost Babbage continued his work whilst Swedish printer, George Scheutz would later construct his own engines based on Babbage’s Difference Engines which were used to produce mathematical and astronomical tables for the British and American governments. His vision of an all-purpose calculating and computing engine would not occur until the arrival of electronic computing in the 1940s onwards.

Forty years on and to commemorate the bicentennial of Babbage’s birth in 1991, the Science Museum in London managed to build a replica of his Difference Engine No.2 using his original designs. A team laboured for almost six years to produce a beast of a machine that contained over 4,000 parts and weighed around 3,000kg – heavier than over 19,700 LG G4 smartphones! The machine worked, vindicating Babbage’s theories, and the Science Museum followed up with the printer Babbage had envisaged to accompany the Difference Engine. It too, had around 4,000 parts, and weighed 2,500kg.

A second Difference Engine was constructed for the ex-Vice President of Microsoft, Nathan Myhrvold in 2008 and there may yet be more to come. Attempts are under way by the Plan 28 charitable organisation (named after one of Babbage’s sets of plans) to first build a three-dimensional computer simulation of his Analytical Engine and then, if significant funds are raised, construct a full size working machine by 2021 – 250 years since Babbage’s birthday. In the words of Plan 28 founder, British programmer, John Graham-Cumming, “What we hope to do is create a working monument to the man who conceived the computer, and to inspire today’s scientists and engineers to dream a century into their future.”

**Written by Clive Gifford, LG CNS Blog’s Regular Contributor**

**Further reading and references:**

A brief explanation of how Babbage’s Difference Engines used the method of finite differences to calculate.

http://www.computerhistory.org/babbage/howitworks/

The website of the organisation looking to build a fully-working Analytical Engine.

http://plan28.org/

An in-depth article on the Analytical Engine.

http://history-computer.com/Babbage/AnalyticalEngine.html

**Side Panel: Five Things You Never Knew About Charles Babbage**

- Fascinated by early railways, in 1838, Babbage invented one of the first pilots or cowcatchers – the device at the front of a locomotive used to clear obstacles away from the rail tracks.
- Babbage and his wife, Georgina had eight children, two of which along with Georgina and Babbage’s father all died of illness in 1827.
- Unheralded at the time of its invention in 1847, Babbage built one of the world’s first ophthalmoscopes for the medical study of the human eye.
- Babbage was a notable cryptologist and during the Crimean War managed to break a number of codes and ciphers including the Vigenère cipher used to keep military messages unreadable by the enemy. Babbage’s work was kept as a military secret and so he did not receive the credit for his work.
- Babbage’s brain is preserved in two different places in London. Half is on display at the Science Museum in Kensington and the other half is found at the Hunterian Museum in the Royal College of Surgeons in Lincoln’s Inn Fields.