The Philosophical Breakfast Club (16 page)

In the de Prony system, even if there was no error on the part of the human computers, there was still a chance for mistakes to creep in. Results were copied by hand onto lists—a process that commonly led to error, when the human eye had to read long and dense columns of numbers, each with many digits. The lists were proofread against the original tables, at which point further errors were commonly made. The lists were then given to a typesetter, who used loose metal type to set the results; error could easily enter here as well, when the typesetter misread the table or picked up the wrong piece of type. The printed copy was then proofread against the original list, a process also vulnerable to error.

Babbage saw that his machine precluded the proofreading errors. The method of finite differences uses the last result to calculate the next one, so that any value depends on all of the earlier ones. To verify an entire table, then, the proofreader need only check the last figure. If the last result is accurate, then one would have a very high degree of confidence in all the calculations that preceded it.

All that remained, then, were the errors that could arise in the hand-copying and printing process. Babbage realized that he needed to construct a printing device that would automatically record the results of the computations.

Babbage devised a mechanism in which the calculated results were automatically sent both to a printer unit, which generated output for quick checking on a roll of paper, and to a stereotyping apparatus, which impressed the results into tables on a soft material such as plaster of Paris. The mold thus produced could be used to cast a solid metal printing plate from which numerous copies could be generated. The mechanism allowed for the customization of the layout of the results: the line height, number of columns, and column margins could all be adjusted as needed. Babbage’s Difference Engine surpassed even de Prony’s great table-making project, by eliminating all possible sources of error.

B
ABBAGE’S INVENTION
was special, even in that age of machinery. Steam engines, locomotives, mechanized looms, the cotton “gin” (short for “engine”), and other machines had been devised to take the place of human or animal physical power. But Babbage’s invention was the first that supplanted not physical but mental labor. Recognizing this, the Astronomical Society would soon describe his Difference Engine as a machine that “substitutes mechanical performance for an intellectual process.”
²⁵
Henry Wilmot Buxton, who befriended Babbage at the end of his life, would later more vividly remark that in the Difference Engine “the marvelous pulp and fibre of a brain had been substituted by brass and iron, [Babbage] had taught wheelwork
to think
, or at least to do the office of thought.” The automata of past centuries and the present day had
simulated
mental processes: the priest who seemed to be praying, the woman who seemed to be flirting. Here was a machine that actually
performed
mental functions. The age of artificial intelligence could be said to have begun with the Difference Engine.

For some, like Babbage, the notion that a machine could do the job of human intelligence was empowering, a way to free up the mathematician for more important work while at the same time ensuring a level of accuracy that no human computer could hope to attain. For others, it raised troubling questions about the value of human minds, just as the mechanized looms and other inventions had raised questions about
the value of human labor, questions that would soon be taken up by a young Karl Marx. If a machine can do the job of human intelligence, are human minds therefore no better than machines? As early as October 1822, Whewell’s friend Julius Hare used the example of Babbage’s brand-new invention to argue that philosophical systems leading to religious skepticism made men out to be no better than “Babbage’s calculating machine,” not “wiser but fuller, not with a more enlarged but with a more occupied understanding.”
²⁶
Surely the human mind is more than a number-cruncher, Hare protested. Yet if a machine could be made to perform the mental functions of mathematical reasoning, were other mental functions far behind? Language, emotions, creativity—would these come next? The very idea of a Difference Engine, for some, provoked anxieties about the problematic relationship between minds and machines. These worries continue to incite spirited debate among philosophers, cognitive scientists, and theologians to this day.

W
HEN HE RETURNED
to London after his visit to Herschel, Babbage began to build a prototype of his Difference Engine. By the spring of 1822, Babbage had a small working model of his first design, which he began to show to friends and colleagues. This model has disappeared. But we know that it approximated part of his planned larger machine, consisting of three columns, with each column containing six figure wheels.
²⁷
It was at least partly, if not completely, automatic, although Babbage had not yet finalized all the technical plans for the operating of his full-scale machine. Babbage optimistically recorded in his journal on May 10, 1822, “My calculating machine is nearly finished.”

Even as he continued to work on the plans, Babbage was publicizing his invention. On June 14, 1822, he read a paper announcing his construction of a table-calculating machine to the new Astronomical Society, an association he and Herschel had helped create two years earlier. Indeed, he had already used the model engine with some success; he noted that “with this machine I have repeatedly constructed tables of square and triangular numbers, as well as a table from the singular formula x
²
+ x + 41.” Babbage’s model Difference Engine had tabulated thirty values for this polynomial in only two and a half minutes. The next summer he was awarded the gold medal of the society.

A few weeks after his paper to the Astronomical Society, Babbage
published an open letter to Sir Humphry Davy, by then president of the Royal Society. In this letter, which he had privately printed and distributed widely, Babbage showed how his planned Difference Engine could perform the work of Prony’s tables, reducing the number of calculators from ninety-six to twelve or even fewer, so that the tables could be printed at far less expense and with far greater accuracy. “Success [in building the complete machine] is no longer doubtful,” he proclaimed. “It must however be attained at a very considerable expense.”
²⁸

Babbage recognized that constructing the engine would require far more money than he had available. He also felt, as he had since the first discussions of the Philosophical Breakfast Club, that the government should finance scientific research. Babbage began to petition the government for funds to construct his machine. He asked Davies Gilbert, vice president of the Royal Society, and a member of Parliament supportive of scientific interests in the House of Commons, to raise the issue with Sir Robert Peel, who was then home secretary (equivalent to our secretary of the interior). Peel was skeptical; he doubted the possibility of a true “scientific automaton,” and did not believe in the usefulness of one even if it could be built.

Not everyone was as obsessed as Babbage with perfect accuracy; to many people—not only politicians like Peel, but also men of science—the printed tables seemed to be precise enough already. Greater accuracy was not worth the huge financial expenditure involved. That may seem surprising today, with our modern-day scientific ideal of precision at all costs. But in Babbage’s day, men of science saw things differently. Although already in the eighteenth century the sciences were becoming more concerned with exact measurement—think of Lavoisier with his balance, weighing the residue from burning substances with a concentrated precision—it was not until the middle and late decades of the nineteenth century that the man of science became a man of measurement and exactitude. Babbage and the Philosophical Breakfast Club as a whole were in the vanguard of this movement, trying to urge the public and the purse-holding government to venerate progress and precision as much as they did.

Even the chemist W. H. Wollaston, whose lectures Babbage had attended in London with Herschel, and whose use of minuscule quantities of chemicals alerted everyone to his acute powers of observation, did not quite see the point of a machine to calculate numbers with absolute
accuracy; he witnessed Babbage’s demonstration model at work and remarked, “All this is very pretty, but I do not see how it can be rendered productive.”
²⁹
Thomas Young, whose careful experiments had provided evidence for the wave theory of light in 1804, had become superintendent of the
Nautical Almanac
in 1818; although he recognized that the calculations of the human computers under his supervision were not perfect, he saw little potential benefit from a machine that could replace them, even if that machine would result in tables with complete correctness. The money requested for building this machine could be better spent elsewhere, he believed. Young proclaimed the Difference Engine “useless.” George Biddell Airy, who would soon become Astronomer Royal, later commented about Babbage that “I think it likely he lives in a sort of dream as to [the machine’s] utility.”
³⁰

But Babbage and his friends believed, as they had since their days spent discussing Bacon at Cambridge, that science required the most accurate measurements and calculations possible. The Analytical Society was formed by Babbage and Herschel, and supported by Whewell, in order to bring the most up-to-date mathematical methods into the physical sciences in Britain. In their own experimental work the men strove to obtain accurate measurements of all the phenomena, and precise calculations of all the data, whether they were studying the interference of light waves, the crystalline structure of minerals, the position of the stars, or the barometric pressure at the top and bottom of a waterfall. Bacon himself had cautioned in the
Novum Organum
that without such precision, “we shall have sciences, fair perhaps in theory, but in practice inefficient.”
³¹

Science itself, and, more important, all the practical applications of science, required exactness in observing, measuring, and counting. Indeed, it seemed obvious to Babbage that his invention was one that Bacon would have heralded as an improvement not only to science but to people’s lives. The Difference Engine would aid science by giving astronomers and other men of science a tool to make perfect calculations. It would enhance lives by averting the horror of shipwreck, rendering more accurate the value of life insurance and the rates of taxation, strengthening the construction of buildings, bridges, and roads, and simplifying the work of just about anyone who relied on tables by making these tables flawless.

Although he was skeptical about the machine, Peel referred the
question of its usefulness to the Royal Society. A committee was convened. Seven of its twelve members were close friends of Babbage’s, including Herschel. Wollaston and Young were also on the committee; Wollaston good-naturedly supported the government providing funding for a machine he felt was unproductive, but Young argued vociferously against it. Young was outvoted. The report was, in the end, quite favorable, concluding that Babbage was “highly deserving of public encouragement in the prosecution of his arduous undertaking.”
³²

Peel reluctantly authorized a grant of £1,500 to “bring to perfection a machine … for the construction of numerical tables.” In July, Babbage met with the chancellor of the exchequer, John Frederick Robinson, who soon would become Lord Goderich. Unfortunately, no minutes were kept of the meeting, so what was actually said and promised remains murky. Later, Lord Goderich believed he had agreed to a one-time grant for building the machine, while Babbage was left with the impression that the government would continue to support him, giving him further funds when necessary. Babbage predicted to Herschel elatedly after the meeting that in a few years his machine would produce “logarithmic tables as cheap as potatoes.”
³³

Babbage began work in earnest. As his plans progressed, he realized that his machine would require some 25,000 parts, made to very precise specifications. This was a completely new kind of undertaking. Britain had not yet made the transition from a craft manufacturing system to mass-production manufacturing, except for the cotton- and wool-weaving machines that had sparked the start of the Luddite movement. Metal parts were still made one at a time, by hand. Each was inevitably slightly different. Parts that needed to match exactly were painstakingly compared to each other and then finished with hand tools such as metal files to make them identical, or as close to identical as possible. It was an arduous, time-consuming process, but it had to be done this way.
³⁴

It was not even possible to farm out work to different workshops. In the 1820s, there were no set manufacturing standards. Each mechanical engineer had his own taps and dies for cutting screws, for example, so that no two screws from two different workshops were the same. A nut cut in one shop could not fit a bolt cut in another. All the parts would have to be made in one workshop.

Babbage recognized that he would need to hire a professional machinist and engineer who would devote his entire workshop to producing
the parts for the Difference Engine, and who could help Babbage design the parts to technical specifications that were possible to attain. His friend Marc Isambard Brunel, who would soon become famous as the builder of the massive tunnel traveling under the Thames from Rotherhithe to Wapping (and who had served on the Royal Society committee reviewing Babbage’s plans), recommended Joseph Clement, a first-rate draftsman and highly skilled toolmaker. Brusque to the point of rudeness, the son of small hand-loomers, Clement had received no formal education, but was extremely talented. He had a reputation for designing and manufacturing parts with acute precision. He also had a reputation for being expensive, but Babbage was flush with money: he had £1,500 at his disposal and, he believed, the promise of more to come. Clement seemed like the perfect choice.