Issue 19 Chance Fall 2005

The Difference Engine

Samantha Hunt

Two Theories, One Train
Imagine that on a train crossing England in the mid 1800s, Charles Babbage watched a common house fly travel into the future. Bumbling from the rear of the carriage to the front, the fly stopped atop a lady’s floral hat and regurgitated. It’s what flies do when they aren’t flying. At that instant, as the creature ceased moving forward, Babbage thought that the time the fly had flown through—moments arrayed behind it like consecutive bread slices—was catching up with the fly now that it had stopped moving forward. Times already experienced were slamming into the fly again as it idled, as the train gained on London. “Wonderful,” Babbage thought, even if his theory wasn’t entirely correct.

Babbage's Analytical Engine, 1834-1871, the first fully automatic calculating machine. Courtesy Science Museum / Science and Society Picture Library, London.


Louis Pasteur, another passenger on this mythic train, twisted his paper into a sword and swatted at the fly. The behatted woman screamed as Pasteur hit his mark. “Madame,” he begged, “forgive me,” and began to explain how house flies’ secret regurgitations are repositories for germs. The woman quickly changed seats thinking she’d encountered a madman. As Pasteur was on his way to share his theory with the Royal Society, his confidence was shaken. He had been considering how best to phrase it: “The reason that so many people are dying is because the air and water are filled with tiny, lethal beings that we cannot see.” Pasteur’s heart sank. It did sound crazy, despite being entirely correct. He did not need to travel into Babbage’s future to know how his ideas would be received in Town.

Imaginary Numbers Charles Babbage (1791-1871)—whose full title is ESQ., M.A., F.R.S., F.R.S.E., F.R.A.S., F. STAT. S., HON. M.R.I.A., M.C.P.S., COMMANDER OF THE ITALIAN ORDER OF ST. MAURICE AND ST. LAZARUS, INST. IMP. (ACAD. MORAL.) PARIS CORR., ACAD. AMER. ART. ET SC. BOSTON, REG. OECON. BORUSS., PHYS. HIST. NAT. GENEV., ACAD. REG. MONAC., HAFN., MASSIL., ET DIVION., SOCIUS. ACAD. IMP. ET REG. PETROP., NEAP., BRUX., PATAV., GEORG. FLOREN., LYNCEI. ROM., MUT., PHILOMATH. PARIS, SOC. CORR., ETC.—was an expert lock-picker, inventor of the heliograph, the cowcatcher, the first speedometer, occulting lights for lighthouses, standard railway gauges, standard screw threads, and a device for walking on water that almost worked. He was also the father of the modern computer, working at a time when the Romantics’ Nature twisted a vine around the Victorians’ wrought-iron Science and Computation, encouraging fertile, if erroneous, experiments that often disregarded the boundaries between the physical and metaphysical. These bold, if mistaken, Frankensteins blossomed into half-bred philosophies such as floral numbers, loose morality, Mesmerism, the musical calculus of the nervous system, independent female intellectuals, algebraic fairies, and robotic life, at a time when poetry drenched scientific thought.

In 1833, Babbage, 42, met Ada Byron, 17, daughter of Annabella Milbanke and everyone’s favorite depraved bard, Lord Byron. Soon after Ada’s birth, following Byron’s alleged affair with his sister, Annabella had taken her five-month-old daughter from her father and begun a lifelong project of rooting out the Byronic, not only from Ada but from all British society. Ada was fed on Reason, strict morality, and math, resulting in an appropriate response: she conducted her scandalous first love affair at age thirteeen, with her math tutor. When she met Babbage, he was intensely interested in both stomach pumps and the railway, as they could reverse natural processes; i.e. digestion could now move from both mouth to stomach and stomach to mouth, while locomotion could move from London to Manchester and Manchester to London. These about-faces contained the kernel of Babbage’s favorite theory, one he perhaps explained to Ada this way: “I believe that if you know a number of facts about an object, you should be able, via computation, to travel these conditions forward and thus to know how the object will exist in time to come.” He imagined riding a train into the by-and-by and returning later that night with a forecast.

“You mean,” Ada might have said, “through math you can predict the future?”
“Not predict. Know.”
“Anything?”
“Anything that can be translated into numbers.” And Babbage had yet to meet an object, he thought, that could not be rendered numerically.
“For example,” Ada perhaps proposed, “which horse will place first in Saturday’s race?”

Charles needed money badly. For years he had been developing a machine called the Difference Engine, never wholly constructed in his lifetime, but which even in skeleton form could tabulate terrifically. More important, even, than tabulation, Charles saw a way in which the apparatus could store what it had learned and act on it again. The Difference Engine and a second version, the Analytical Engine, became, by the 1850s, proto-computers—or they would have been, had Charles had the money to complete construction. The Difference Engine could think for itself. By using a method of finite differences, the engine was able to compute a programmed formula on an infinite string of integers without human prompting—a wonder to a budding Victorian, for whom automation still existed almost exclusively in dreams.

The Difference Engine was terrifically bulky and ornate. Nearly as large as a wardrobe, it was made up of two thousand shiny brass and steel parts, some of which were etched with tiny numbers where results could be read. Babbage initially tried to pitch the Difference Engine as a mechanism for tabulating exact logarithms and nautical chart numbers that would aid in latitude and longitude navigation—a sensible use, but one that employed only a fraction of the engine’s powers. One theory says that Ada saw a different application for the Difference Engine: gambling on horses.

To these mathematicians, a horse was the number of teeth in its mouth, the length of its mane, the variety of its dapples, how fast it could run, even the sum total of putrefaction that its carcass would produce once the maggots were sold for medicinal purposes. Babbage wrote:

Small pieces of horse flesh are piled up. In a few days the putrid flesh is converted into a living mass of maggots. These are sold by measure: One horse yields maggots which sell for 1s. 5d. The rats which frequent the fresh carcass of a horse are innumerable. 16,000 rats were killed in one room in four weeks, without any perceptible diminution of their number. The furriers purchase the rat skins at about 3s the hundred.

Ada was mesmerized. Not with love, but by a view of the world that allowed for both the mechanical morality of Annabella and Byron’s wild curves. She, too, needed money. So it was an easy next step to take, applying the years of math tutoring to her newest gaming interest.

To proceed with the computational adventure and place bets in public, booking agents required Ada to secure a letter of permission from her husband, William Lovelace, that would permit her to gamble. As a woman, without her husband’s allowance, Ada was worth nothing, and so could not be responsible for any debt she incurred. Though the fortune they lived on was hers, women were not legally entitled to own things—a restriction that easily explains her monstrously “unfeminine” attraction to wagering in the first place. Permission granted, Ada began to act as bookie for a syndicate of acquaintances. Simultaneously, she set to work publishing articles on the wonders of the Difference Engine, drafting programs for the machine to run on and scheming over ways that the Analytical Engine could marry music to numbers. Though much of the written evidence for Ada’s “gaming fever” was ultimately veiled or destroyed by Annabella, one irresistible theory is that, drawing upon her earlier experience writing a Difference Engine program to tabulate Bernoulli numbers (the sums of powers of consecutive integers; extremely important to number theory), she developed a formula to render racehorses as numerics: weight, speed in past races, places won, jockey’s height, horse’s leg length, horse’s age, etc. These values could be plugged into the Difference Engine to produce what would today be called odds.

Dr. Frankenstein
In 1837, in the converted ballroom of a grand house known as Fyne Court in the Quantock Hills of Somerset, a man named Andrew Crosse distilled solutions into beakers, skipped meals, tore at his hair, grew mineral crystals in bone-china teacups, assembled lightning-fueled batteries in Leyden jars, and spoke to himself in verse:

Crosse, yes, Crosse will be selected
When he in turn makes life electric!


A true mad scientist, Crosse was responsible for temporarily revivifying the notion of spontaneous generation. He harkened back to the good old days, pre-Enlightenment and pre–ex-ovo omnia, when folks believed that life could arise from nothing more than a bolt of electricity. Crosse dripped a chemical mixture over pumice stone, then battered it with an electric charge. The pumice began to precipitate stalactites, and a few days later wiry insects, Acari electricus, crawled forth. He had done it! Faraday was fascinated. Mary Shelley was inspired to write Frankenstein, modeling her doctor on Crosse himself. But sadly, spontaneous the bugs were not. Unlike Pasteur, Crosse was wrong—however wonderfully so.

Here again Ada was nevertheless entranced, not only by Babbage’s calculation fever, but by the legacy of automatic, self-perpetuating creation promulgated by Crosse’s experiments. Perhaps she was also influenced by the famous proximity of Byron to the Shelleys, and the celebrated invitation to ghost-story writing, issued by her father one stormy night, that supposedly stimulated the virgin birth of Mary’s novelistic brain-child. In any case, Ada paid a visit to Fyne Court, where it soon became evident that her fascination with illicit creation might hinge on the fact that she was painfully in love with Crosse’s son, John. Troublesome, this, as both she and John were married to other people. Nevertheless, in good Byronic fashion, John became Ada’s lover and an active member of her gambling syndicate, an assemblage that drew on her connections both seedy and aristocratic: John Crosse, Richard Ford (the travel writer and son of a government magistrate who, it is rumored, recruited Wordsworth as informant and spy during the French Revolution),William Nightingale (Florence’s father), and two mystery men known as Fleming and Malcolm.

With the most important race in England approaching, the York Derby of 1851, Ada concentrated her forces, both psychic and monetary, on her favorite horse, Voltigeur. The steed, named for his sire, Voltaire, was no doubt attractive to Ada for the power of his name’s double association, to both the Italian electrical physicist Alessandro Volta, and to Andrew Crosse’s electrical experiments. She felt sure that Voltigeur would win, and her bets reflected her certainty: She doubled the risk, wagering the same funds twice, once with herself and again with a professional bookie. Sadly, math and science had other forces to contend with. Voltigeur, not made from pure numbers but from flesh and bone, lost the race.

Ada’s debts opened before her as a chasm: 3,200 pounds, large even by today’s standards, particularly for a woman with no income. Within days, Malcolm was blackmailing her for his losses. He was fully aware of what might happen to Ada if Annabella were to find out about her daughter’s unseemly activities. William paid Malcolm off. Ada in turn pawned her family jewels so that she and John Crosse could continue gambling. The hocked items were discovered and recovered by Annabella, but Ada pawned them again. And then the real dark streak in Ada was diagnosed. It was not her father’s amorality or her numerological obsession, but an illegitimate parthenogenesis of the most monstrous sort, a uterine cancer gone too far. Unlike the proto-computers she loved, the growth of this artificial life inside Ada’s womb seems like the final revenge of the feminine upon Ada’s bolder behaviors. Ada’s husband and doctors decided to keep the cancer a secret from her.

It seemed that Charles and Ada were done for. Lacking either legitimate or illegitimate funding, the Difference Engine would not be built until 1991, when the Science Museum of London marked the bicentennial of Babbage’s birth by crafting their own Difference Engine from Babbage’s sketches and thus proving, far too late, that Charles Babbage had invented the computer for which Ada Lovelace wrote one of the first computer programs.

In the Department of Defenses
Great failures in homegrown science—Charles’s water-walking device, Ada’s wagering debacles, Andrew Crosse’s inability to spontaneously generate life, or even Ada’s doctor’s incapacity to cure her cancer with prescriptions of copious red wine and opium—seem to have disappeared into the static, silent past. Failed experiments are rarely remembered. Today, many, many people are nobly working on novels or plays or poems in their off-hours. But who is developing a device for teleportation, or grafting human DNA with the great blue heron’s in her basement after work? The days of building computers in garages are gone, and it is becoming nearly impossible to operate a laboratory in this country without receiving money and meddling from either a large corporation or the US Department of Defense. Pasteur’s heirs—the scientific pioneers who have been taken as heroes into the bosom of history—seem to have little or no relation, now, to the madmen and renegade girls left by the wayside of quixotic experiment. But maybe the bread-slice moments are still hurtling forward, and about to crash into us when we least expect it.

A year after Voltigeur’s defeat, Ada died at the age of 36. Babbage, in turn, began to work on his most astounding and beautiful project yet. It was a formula that would haunt him for the rest of his life, because he never could get it quite right: a theorem for predicting the chances that someone dead would come back to life. In a twisted sense, against all odds, it worked. Babbage had a moon crater named after him, and in 1971 the US Department of Defense created a computer language for discharging weapons on the enemy. The language is named ADA.

Samantha Hunt is the author of a novel, The Seas (MacAdam/Cage Publishing, 2004). She is a writer and an artist from New York.

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