2.4 The Difference Engine

The project to build the Difference Engine began in August or September of 1823. Two rooms in Babbage’s house were converted into workshops and a third into a forge. On the recommendation of a friend, Babbage hired Joseph Clement, a first-rate mechanical engineer, to serve as chief engineer and to fashion most of the parts in his own factory. Clement, who had worked for Henry Maudslay, one of Britain’s leading engineers, was down on his luck when Babbage entered his life, with only one good lathe to his name. Clement and the draftsmen and workmen he hired played a pivotal role in the construction of the engine, and we shall hear a good deal more about him.

Next Babbage undertook a thorough investigation of the state of machine manufacture in British industry, going on a tour with Georgina of factories throughout England and Scotland. Machines were an uncommon sight in everyday British life at the time. Steamships had only begun to appear and the proliferation of the railroad was ten years away. The most common mechanical objects were clocks, watches, locks, guns, and pumps. There was, of course, a much wider range of machinery in industry: looms, lathes, stampers, turbines, shears, presses, boring engines, milling machines, and so on. The Difference Engine would be vastly more intricate than an y of these – in fact, it probably would be the most sophisticated machine made up to that time – and Babbage, a perfectionist, demanded construction standards that the machine tools of the period simply could not meet.

A sketch of the mechanics of adding and carrying with the Difference Engine, drawn in October and November 1836.

The engine was designed to operate to the sixth order of difference (Muller’s would have handled only three orders); calculate numbers to the twentieth place; and print out forty-four digits a minute. It required hundreds of carefully machined components, all working in perfect coordination; any slack in the gears might throw the engine out of whack. As he got deeper into the project, however, Babbage realized that he couldn’t hope to meet the engine’s precise specifications without better machine tools, and he therefore redirected his effort, putting much sweat and ingenuity into the design of new tools. In general, he would design a part or series of parts for the engine, and then design and build the tools to make them. In the course of the process, he invariably conceived of a better way to make either the parts or tools, and the whole procedure had to be repeated. Although his ambitious, multilayered enterprise lifted the British machine tool industry to new heights, it also delayed the engine and greatly inflated its cost.

In 1827, four years after the project had begun, Babbage’s father died. Babbage inherited about £100,000, the bulk of his father’s estate, which made him a very rich man, with enough money to help finance the project and to support his family in style. Despite the government’s financial help, he spent thousands of pounds on the Difference Engine and the grand conception that followed it, the Analytical Engine. Yet, at the very time that Babbage came into the means to enjoy his life to the fullest, death visited his family three more times within the year. His second oldest son died in July; his wife passed away the following month, apparently from complications caused by childbirth; and his newborn son died soon after.

Filled with sorrow, Babbage left England for a year-long tour of the Continent. Clement continued to work on the Difference Engine, but the endeavor fell into low gear. Fortunately, the trip did Babbage a great deal of good and he returned in better spirits. Although his famous charm, wit, and humor had been restored, Babbage had clearly changed. His family life was gone and an uncharacteristic tone of bitterness entered his public controversies – a tone that had not been there when Georgina was alive. (As he grew older, and his dreams fell by the wayside, the bitterness deepened.) Trying to forget his loss, Babbage threw himself into the engine project and his numerous social and political activities. He was an outspoken Liberal and managed one candidate’s successful Parliamentary campaign in 1829. Three years later, he ran for Parliament himself, placing third in a field of five. If another woman entered his life, there is no record of it.

While abroad, Babbage had reviewed the project’s accounts. In addition to the government’s £1,500, he had spent £1,975 of his own money. As he understood the terms of his agreement with the government, the Treasury was supposed to reimburse him for any expenses above the original £1,500. Therefore, Babbage (and some of his influential friends) asked the Treasury to pay him back and authorize more funds. However, Robinson, who had since left the Exchequer, claimed that he had never committed the Treasury to more than the original sum and that he most certainly had not given Babbage a blank check. Since neither of them had put their agreement into writing, it was one man’s word against the other’s. Babbage appealed to the Duke of Wellington, the current prime minister, and Wellington ordered the Treasury to evaluate the entire project. The Treasury, in turn, asked the Royal Society for an appraisal of the engine, and once again the society endorsed Babbage unqualifiedly. Then Wellington decided to see the engine for himself.

It was November 1829, and Babbage had little to show for six years of labor. There was the first model of the engine, assembled by Babbage in 1822; Clement’s superior machine tools, which had advanced the state of machine tooling and made the engine feasible; and hundreds of drawings and parts for the engine itself. The device was obviously several years and thousands of pounds from completion. Yet Wellington was persuaded. A military man, he had a fair amount of technical knowledge and a solid understanding of the engine and its potential benefits to science, technology, and England. At his order, the government disbursed £7,500 in late 1829 and early 1830, and the project resumed after a nine-month hiatus.

Babbage, meanwhile, faced another critical problem: Clement. Even before he had left for Europe, he had suspected the chief engineer of padding his bills. He also believed that Clement had built special lathes and other costly tools at the venture’s expense, not so much to use them on the engine as to enrich his own shop. In those days, the law held that a workman had the right to his own tools, even if they had been constructed on an employer’s time and with an employer’s money. A holdover from medieval times, when a craftsman’s tools were no more expensive or elaborate than hammers and files, the law was unreasonable in an era of expensive machine tools. But the law was the law, and Babbage couldn’t claim Clement’s tools for himself or for the government, the engine’s legal owner. As long as he employed Clement, the issue of ownership was a moot point, although it surely would turn into a major dilemma if, for whatever reason, he decided to let Clement go. So Babbage took the only step open to him: he refused to pay Clement’s bills until a three-man panel of engineers was appointed to inspect the work and to approve the bills. The arrangement was a common practice at the time, and it worked for a while.

A sketch of the Analytical Engine's driving and directive apparatus. The barrel, which contained the machine’s internal operating instructions, is on the far right.

Babbage also wanted Clement to move his workshop closer to his Dorset Street home. His house and Clement’s shop were four miles apart, and Babbage, who often fretted about his health, wanted the engine (or, rather, the many parts that made it up), tools, and plans placed in a more convenient and comfortable setting. He also worried about the safety of his project, since fire was an ever-present hazard in nineteenth-century London and Clement’s shop was not fireproof. Clement stoutly resisted the change; he knew that his freedom of action and profits would certainly shrink under Babbage’s direct supervision. But the government went along with Babbage, and an architect was commissioned to build the appropriate facilities on Babbage’s property. Although Babbage offered to loan Clement a small house next to his, Clement was not appeased.

A plan for the operation of the Analytical Engine’s variable-card counting mechanism. Among other things, the variable cards supplied the initial numerical values of the variables in an equation.

In 1832, almost ten years after the project had begun, there were enough parts to assemble a section of the engine. Consisting of six vertical axles and a few dozen gears, the section was about twenty-four inches high, nineteen inches wide, and fourteen inches deep. It worked perfectly, solving equations to the second order of difference and yielding six-digit results. It was a beautiful piece of machinery, one of the finest and most sophisticated machines of its time – as solid as the Empire (back then!) and as dependable as the pound (ditto). The Arithmometer was a toy by comparison. The precious invention was moved to a new fireproof building adjacent to Babb age’s house, where he showed it off to his friends at his famous Saturday night parties. Wellington, proud of his role in the project, was a regular guest.

Babbage’s weekly soirees were the most popular parties in London. His home was one of the most interesting in the capital, with all sorts of amusing gadgets to play with. In addition to the famous engine, on display in a glass and mahogony case, he had a foot-high silver automaton of a dancing woman dressed in a fancy gown. Babbage knew many of the most important people in England – writers, actors, aristocrats, and politicians, as well as scientists, engineers, and businessmen – and he often pops up in their diaries. Charles Darwin wrote: “I remember a funny dinner at my brother’s, where, amongst a few others were Babbage and Lyell [Charles Lyell, the founder of modern geology], both of whom liked to talk. Carlyle however silenced everyone by haranguing during the whole dinner on the advantages of silence. After dinner, Babbage, in his grimmest manner, thanked Carlyle for his very interesting lecture on silence.”

After the engine had been transferred to his property, Babbage continued to press Clement to make the move, too. But Clement put up a big fuss. He submitted a bloated estimate of his moving expenses and demanded £660 a year to maintain two homes and to run a divided business. Outraged, the Treasury refused his claims. Most of the £12,000 that had been spent on the engine so far had passed through Clement’s hands and he had earned a great deal of money. He had also equipped his shop with thousands of pounds’ worth of machine tools, designed by Babbage and paid for by the government, and which were, under the law, his property.” My Lords,” the Treasury wrote,” cannot but express their surprise that Mr. Clement should have advanced so unreasonable and inadmissable a claim.”

Clement’s selfishness became a major obstacle to the completion of the engine, and it was all downhill from here. The chief engineer agreed to submit his claims to the arbitrators but, realizing that they were as unsympathetic to his cause as the Treasury, changed his mind and then simply refused to budge. Under the circumstances, Babbage declined to pay his bills (normally, Babbage paid Clement and the Treasury paid Babbage), instructing him thereafter to submit his chits directly to the Treasury, which meant that he would no longer be reimbursed promptly. In response, Clement, who seems to have been deeply jealous of Babbage’s talent and wealth, fired his staff and refused to turn over the engine’s plans or parts until his bills were paid. As a result, the project ground to a halt. Unfortunately, Clement had the upper hand and there was nothing to do but examine his accounts and pay him off, which the Treasury finally did. On 16 July 1834, more than a year after work had stopped, Clement finally relinquished the goods. Babbage wrote the Treasury: “The drawings and parts of the Engine are at length in a place of safety – I am almost worn out with disgust and annoyance at the whole affair.”

Although Babbage tried to resurrect the project, his appeals fell between the cracks of British politics. There were several changes in administration in 1834 and 1835 – from Melbourne to Wellington to Peel and back to Melbourne – and Babbage’s problems were lost in the shuffle. Moreover, he foolishly confounded the issue by informing the government that he had conceived of a far more powerful and versatile machine – an Analytical Engine – which rendered the Difference Engine obsolete. The Analytical Engine could do all that its predecessor could do, and a great deal more. Under the circumstances, he suggested it might be more prudent and less expensive to write off the Difference Engine and build the newer version. This was not what the government, which had shelled out £17,000 for a glimmer in an inventor’s eye, wanted to hear.

For his part, Babbage, who had spent £6,000 of his own money on the endeavor, regarded the government as fatally shortsighted and ill-equipped to lead England into the industrial age. The criticism was uncannily astute, and in making it, Babbage was, as usual, ahead of his time. “I have… been compelled to perceive,” he wrote his friend, Edward, duke of Somerset, in 1833, “that of all countries England is that in which there exist the greatest number of practical engineers who can appreciate the mechanical part whilst at the same time it is of all others that country in which the governing powers are most incompetent to understand the merit either of the mechanical or mathematical.”

Not surprisingly, the government grew tired of Babbage’s importunities. Wellington’s successors lacked his grasp of science and technology and scoffed at Babbage’s work. “What shall we do to get rid of Babbage’s calculating machine… worthless to science in my view,” Prime Minister Peel wrote to an associate. “If it would calculate the amount and the quantum benefit to be derived to science it would render the only service I ever expect to derive from it.” In 1842 – nineteen years after Babbage, full of confidence and high spirit, had started the project – Peel got his way. The venture was officially canceled and the engine wound up on display at the Science Museum in London.

But one cannot blame the project’s failure entirely on the government. Clement’s selfishness, petty and indefensible, and Babbage’s perfectionism, which brooked no shortcuts, were also responsible.

Back                                                                                                                                   Continue