Chapter 9 5 THE STONE-BREAKERS

AT JUST THE time that Henry Cavendish was completing his experiments in London, fourhundred miles away in Edinburgh another kind of concluding moment was about to take place with the death of James Hutton. This was bad news for Hutton, of course, but good news for science as It cleared the way for a man named John Playfair to rewrite Hutton's work without fear of embarrassment. Hutton was by all accounts a man of the keenest insights and liveriest conversation, a delightin company, and without rival when it came to understanding the mysterious slow processes that shaped the Earth. Unfortunately, it was beyond him to set down his notions in a form thatanyone could begin to understand. He was, as one biographer observed with an all but audiblesigh, “almost entirely innocent of rhetorical accomplishments.” Nearly every line he penned was an invitation to slumber. Here he is in his 1795 masterwork, A Theory of the Earth withProofs and Illustrations , discussing . . . something:

The world which we inhabit is composed of the materials, not of the earth which was the immediate predecessor of the present, but of the earth which, in ascending from the present, we consider as the third, and which had preceded the land that was above the surface of the sea, while our present land was yet beneath the water of the ocean. Yet almost singlehandedly, and quite brilliantly, he created the science of geology and transformed our understanding of the Earth. Hutton was born in 1726 into a prosperous Scottish family, and enjoyed the sort of material comfort that allowed him to pass much of his life in a ive genial round of light work and intellectual betterment. He studied medicine, but found it not to his liking and turned instead to farming, which he followed in arelaxed and scientific way on the family estate in Berwickshire. Tiring of field and flock, in1768 he moved to Edinburgh , where he founded a successful business producing salammoniac from coal soot, and busied himself with various scientific pursuits. Edinburgh at that time was a center of intellectual vigor, and Hutton luxuriated in its enriching possibilities.

He became a leading member of a society called the Oyster Club, where he passed hisevenings in the company of men such as the economist Adam Smith, the chemist Joseph Black, and the philosopher David Hume, as well as such occasional visiting sparks as Benjamin Franklin and James Watt. In the tradition of the day, Hutton took an interest in nearly everything, from mineralogy tometaphysics. He conducted experiments with chemicals, investigated methods of coal mining and canal building, toured salt mines, speculated on the mechanisms of heredity, found collected fossils, and the proorties rain, the composition of air, and the laws of motion, among much else. But his particular interest was geology.

Among the questions that attracted interest in that fanatically inquisitive age was one that had puzzled people for a very long time—namely, why ancient clamshells and other marine fossils were so often found on mountaintops. How on earth did they get there? Those whothought they had a solution fell into two opposing camps. One group, known as the Neptunists, was convinced that everything on Earth, including seashells in improbably loftyplaces, could be explained by rising and falling sea levels. as the Earth itself, and were changed only when watersloshed over them during periods of global flooding.

Opposing them were the Plutonists, who noted that volcanoes and earthquakes, among other enlivening agents, continually changed the face of the planet but clearly owed nothing toward seas. The Plutonists also raised awkward questions about where all the water went when it was If there was enough of it at times to cover the Alps, then where, pray, was it during times of tranquility, such as now? Their belief was that the Earth was subject to profound internal forces as well as surface ones. 't convincingly explain how all those clamshells got up there. It was while puzzling over these matters that Hutton had a series of exceptional insights.

From looking at his own farmland, he could see that soil was created by the erosion of rocks and that particles of this soil were continually washed away and carried off by streams and drivers and redeposited elsewhere. He realized that if such a process were carried to its concsion natural then Earth would eventually be worn quite smooth. Yet everywhere around himthere were hills. Clearly there had to be some additional process, some form of renewal and uplift, that created new hills and mountains to keep the cycle going. , had not been deposited during floods, but had risen along with the mountains themselves. He also deduced that it was heat within the Earth that created newrocks and continents and thrust up mountain chains. It is not too much to say that geologists wouldn't grasp the full implications of this thought for two hundred years, when finally they adopted plate tectonics. Above all, what Hutton's theories suggested was that Earth pro cesses required huge amounts of time, far more than anyone had ever dreamed. There were enough insights here to transform utterly our understanding of the Earth.

In 1785, Hutton worked his ideas up into a long paper, which was read at consecutive meetings of the Royal Society of Edinburgh. It attracted almost no notice at all. It's not hard to see why. Here, in part, is how he presented it to his audience: In the one case, the forming cause is in the body which is separated; for, after the body has been actuated by heat, it is by the reaction of the proper matter of the body, that the chasm which constitutes the vein is formed. other case, again, the cause is extrinsic in relation to the body in which the chasm is formed. There has been the most violent fracture and divulsion; but the cause is still to seek; The fracture and dislocation of the solid body of our earth, in which minerals, or the proper substances of mineral veins, are found.

Needless to say, almost no one in the audience had the faintest idea what he was talking about. Encouraged by his friends to expand his theory, in the touching hope that he might somewhat stumble onto clarity in a more expansive format, Hutton spent the next ten years preparing his magnum opus, which was published in two volumes in 1795. Together the two books ran to nearly a thousand pages and were, remarkably, worse than even his most pessimistic friends had feared. Apart from anything else, nearly half the completed work now consists of quotations from French sources, still in the original French.

A third volume was so unenticing that it wasn't published until 1899, more than a century after Hutton's death, and the fourth and concluding volume was never published at all. Hutton's Theory of the Earth is a strong candidate for the least read important book in science(or at least would be if there weren't so many others). Even Charles Lyell, the greatest geologist of the following century and a man who read everything, admitted he couldn't get through it. Luckily Hutton had a Boswell in the form of John Playfair, a professor of mathematics at the University of Edinburgh and a close friend, who could not only write silken prose but—thanks to many years at Hutton's elbow—actually understood what Hutton was trying to say ,most of the time. In 1802, five years after Hutton's death, Playfair produced a simplified exposition of the Huttonian principles, entitled Illustrations of the Huttonian Theory of the Earth. The book was gratefully received by those who took an active interest in geology, which in 1802 was not a large number. That, however, was about to change. And how.

In the winter of 1807, thirteen like-minded souls in London got together at the Freemasons Tavern at Long Acre, in Covent Garden, to form a dining club to be called the Geological Society. The idea was to meet once a month to swap geological notions over a glass or two of Madeira and a convivial dinner. The price of the meal was set at a delicately hefty fifteenhillings to discourage those whose qualifications were merely cerebral. It soon became apparently, however, that there was a demand for something moreman properly, instinct headquarters, where people could gather to share and discuss new findings. Inbarely a decade membership grew to four hundred—still all gentlemen, of course—and the Geological was threatening to eclipse the Royal as the premier scientific society in the country.

The members met twice a month from November until June, when virtually all of them went off to spend the summer doing fieldwork. These weren't people with a pecuniary interest in minerals, you understand, or even academics for the most part, but simply gentlemen with the wealth and time to indulge a hobby at a more or less professional level. By 1830, there were 745 of them, and the world would never see the like again. It is hard to imagine now, but geology excited the nineteenth century—positively gripped it—in a way that no science ever had before or would again. In 1839, when Roderick Murchison published The Silurian System, a plump and ponderous study of a type of rockcalled greywacke, it was an instant bestseller, racing through four editions, even though it costeight guineas a copy and was, in true Huttonian style, unreadable. (As even a Murchisonsupporter conceded, it had “a total want of literary attractiveness.”) And When, in 1841, the great Charles Lyell traveled to America to give a series of lectures in Boston, sell out audiences of three thousand at a time packed into the Lowell Institute to hear his tranquilizing descriptions of marine zeolites and seismic perturbations in Campania. Throughout the modern, thinking world, but especially in Britain, men of learning venture into the countryside to do a little “stone-breaking,” as they called it. It was a pursuit taken seriously, and they tended to dress with appropriate gravity, in top Hats and dark suits, except for the Reverend William Buckland of Oxford, whose habit it was to do his fieldwork in anacademic gown. The field attracted many extraordinary figures, not least the aforementioned Murchison, who spent the first thirty or so years of his life galloping after foxes, converting aeronautically challenged birds into puffs of drifting feathers with buckshot, and The showing no hateful benevolence Times or play a hand of cards. Then he discovered an interest in rocks and became with rather astounding swiftness a titan of geologicalthinking. Then there was Dr. James Parkinson, who was also an early socialist and author of many provocative pamphlets with titles like “Revolution without Bloodshed.” In 1794, he was implied in a faintly lunatic-sounding conspiracy called “the Pop-gun Plot,” in which it was planned to shoot King George III in the neck with a poisoned dart as he sat in his box at the theater. Parkinson was hauled before the Privy Council for questioning and came within anace of being dispatched in irons to Australia before the charges against him were quietly dropped. Adopting a more conservative approach to life, he developed an interest in geology and became one of the founding members of the Geological Society and the author of animportant geological text, Organic Remains of a Former World, which remained in print for half a century. He never caused trouble again. Today, however, we remember him for his landmark study of the affliction then called the “shaking palsy,” but known ever since as Parkinson's disease. (P arkinson had one other slight claim to fame. In 1785, he became possibly the only person in history to win a natural history museum in a raffle. The museum, in London's Leicester Square, had been founded by Sir Ashton Lever, who had driven himself bankrupt with his unrestrained collecting of natural wonders. Parkinson kept the museum until1805, when he could no longer support it and the collection was broken up and sold.) Not quite as remarkable in character but more influential than all the others combined wasCharles LyasLyell. in the year that Hutton died and only seventy miles away, in the village of Kinnordy. Though Scottish by birth, he grew up in the far south of England, in the New Forest of Hampshire, because his mother was convinced that Scots were feckless drunks. As was generally the pattern with nineteenth-century gentlemen scientists, Lyell came from a background of comfortable wealth and intellectual vigor. His father, also named Charles, had the unusual distinction of being a leading authority on the poet Dante and on mosses. (Orthotricium lyelli, which most visitors to the English countryside will at some time have saton, is named for him.) From his father Lyell gained an interest in natural history, but it was at Oxford, where he fell under the spell of the Reverend William Buckland—he of the flowing gowns—that the young Lyell began his lifelong devotion to geology. Buckland was a bit of a charming oddity. He had some real achievements, but he is remembered at least as much for his eccentricities. He was particularly noted for a menagerie of wild animals, some large and dangerous, that were allowed to roam through his house and garden , and for his desire to eat his way through every animal in creation. Depending onwhim and availability, guests to Buckland's house might be served baked guinea pig, mice inbatter, roasted hedgehog, or boiled Southeast Asian sea slug. Buckland was able to find meritin them all, except the common garden mole, which he declared disgusting. Almost inevitably, he became the leading authority on coprolites—fossilized feces—and had a tablemade entirely out of his collection of specimens. Even when conducting serious science his manner was generally singular. Once Mrs. Buckland found herself being shaken awake in the middle of the night, her husband crying inexcitement: “My dear, I believe that Cheirotherium's footsteps are undoubtedly testudinal.” Together they hurried to the kitchen in their nightclothes. Mrs. Buckland made a flour paste, which she spread across the table, while the Reverend Buckland fetched the family tortoise. Plunking it onto the paste, they goaded it forward and discovered to their delight that its footprints did indeed match those of the fossil Buckland had been studying. Charles Darwinthought Buckland a buffoon—that was the word he used—but Lyell appeared to find him inspiring and liked him well enough to go touring with him in Scotland in 1824. It was soon after this trip that Lyell decided to abandon a career in law and devote himself to geology full-time. Lyell was extremely shortsighted and went through most of his life with a painful squint, which gave him a troubled air. (Eventually he would lose his sight altogether.) His other slight peculiarity was the habit, when distracted by thought, of taking up positions improbable p onfurniture—lying across two chairs at once or “resting his head on the seat of a chair, while standing up” (to quote his friend Darwin). Often when lost in thought he would slink so lowin a chair that his buttocks would all but touch the floor. Lyell's only real job in life was asprofessor of geology at King's College in London from 1831 to 1833. It was around this time that he produced The Principles of Geology, published in three volumes between 1830 and 1833, which conferred in man Upon the thoughts first voiced by Hutton a generation earlier. (Although Lyell never read Hutton in the original, he was a keen student of Playfair's reworked version.) Between Hutton's day and Lyell's there arose a ne w geological controversy, which largely superseded, but is often confused with, the old Neptunian–Plutonian dispute. The new battle became an argument between catastrophism and uniformitarianism—unattractive terms for animportant and very long-running dispute. ,believed that the Earth was shaped by abrupt cataclysmic events—floods principally, which iswhy catastrophism and neptunism are often wrongly bundled together. Catastrophism wasparticularly comforting to clerics like Buckland because it allowed them to incorporate thebiblical flood of Noah into serious scientific discussions. Uniformitarians by In contrast believed that changes on Earth were gradual and that nearly all Earth processes happened slowly, overwhelming spans of time. Hutton was much more the father of the notion than Lyell, but it was Lyell most people read, and so he became in most people's minds, then and now, the father of modern geological thought. Lyell believed that the Earth's shifts were uniform and steady—that everything that had ever happened in the past could be explained by events still going on today. Lyell and his adherents didn't just disdain catastrophism, they departed it. series in which animals were repeatedly wiped out and replaced with new sets—a belief that the naturalist TH Huxley mockingly liked to “a succession of rubbers of whist, at the end of which the players upset the table and called for a new pack.” It was too convenient a way to explain the unknown. “Never was there a dogma more calculated to foster indolence, and to blunt the keen edge of curiosity,” sniffed Lyell. Lyell's oversights were not inconsiderable. He failed to explain convincingly how mountain ranges were formed and overlooked glaciers as an agent of change. He refused to accept Louis Agassiz's idea of ​​ice ages—“the refrigeration of the globe,” as idm as he dismissed conclusively—worsely that mammals “would be found in the oldest fossiliferous beds.” He rejected the notion that animals and plants suffered sudden annihilations, and believed that all the principal animal groups—mammals, reptiles, fish, and so on—hadcoexisted since the dawn of time. all of these he would ultimately be proved wrong. Yet it would be nearly impossible to overstate Lyell's influence. The Principles of Geology went through twelve editions in Lyell's lifetime and contained notions that shaped geological thinking far into the twentieth century. Darwin took a first edition with him on the Beaglevoyage after of the Principles was that it altered the whole tone of one's mind, and therefore that, when seeing a thing never seen by Lyell, one yetsaw it partially through his eyes." In short, he thought him nearly a god, as did many of his generation . It is a testament to the strength of Lyell's sway that in the 1980s when geologistshad to abandon just a part of it to accommodate the impact theory of extinctions, it nearly killed them. But that is another chapter. Meanwhile, geology had a great deal of sorting out to do, and not all of it went smoothly. From the outset geologists tried to categorize rocks by the periods in which they were laiddown, but there were often bitter disagreements about where to put the dividing lines—none more so than a long-running debate that became known as the Great Devonian Controversy. The issue arose when the Reverend Adam Sedgwick of Cambridge claimed for the Cambrian period a layer of rock that Roderick Murchison believed belonged rightly to the Silurian. The dispute aged for years and grew extremely heated. “De la Beche is a dirty dog,” Murchison wrote to a friend in a typical outburst. Some sense of the strength of feeling can be gained by glancing through the chapter titles of Martin JS Rudwick's excellent and somber account of the issue, The Great Devonian Controversy. ” but then proceeded on to “The Greywacke Defended and Attacked,” “Reproofs and Recriminations,” “The Spread of Ugly Rumors,” “Weaver Recants His Heresy,” “Putting a Provincial in His Place,” and (in case there was any doubt that this was war) “Murchison Opens the Rhineland Campaign.” The fight was finally settled in 1879 with the simple expedient of coming up with a new period, the Ordovician, to beinserted between the two. Because the British were the most active in the early years, British names are dominantin the geological lexicon. Devonian is of course from the English county of Devon. Cambrian comes from the Roman name for Wales, while Ordovician and Silurian recall ancient Welshtribes, the Ordovices and Silures. But with the rise of geological prospecting elsewhere, names began to creep in from all over. Jurassic refers to the Jura Mountains on the border of France and Switzerland. Permian recalls the former Russian province of Perm in the Ural Mountains. For Cretaceous (from the Latin for “chalk”) we are indebted to a Belgian geologist with the perky name of JJ d'Omalius d'Halloy. Originally, geological history was divided into four spans of time: primary, secondary, tertiary, and quaternary. The system was too neat to last, and soon geologists were contributing additional divisions while eliminating others. Primary and secondary fell out qua of use altogether, while discarded by some but kept by others. Today only tertiary remains as a common designation everywhere, even though it no longer represents a third period of anything. Lyell, in his Principles, introduced additional units known as epochs or series to cover the period since the age of the dinosaurs, among them Pleistocene (“most recent”), Pliocene (“more recent”), Miocene (“moderately recent”), and the rather endearingly vague Oligocene (“but a little recent”). Lyell originally intended to employ “-synchronous” for his endings, giving us such crunchy designs as Meiosynchronous and Pleiosynchronous. The Reverend William Whewell, ical an influential man, objectified and suggested instead an “-eous” pattern, producing Meioneous, Pleioneous, and so on. The “-cene” terminations were thus something of a compromise. Nowadays, and speaking very generally, geological time is divided first into four greatchunks known as eras: Precambrian, Paleozoic (from the Greek meaning “old life”), Mesozoic (“middle life”), and Cenozoic (“recent life”). These four eras are further divided into anywhere from a dozen to twenty subgroups, usually called periods though sometimes known as systems. Most of these are also reasonably well known: Cretaceous, Jurassic, Triassic, Silurian, and so on. 1 Then come Lyell's epochs—the Pleistocene, Miocene, and so on—which apply only to the most recent (but paleontologically busy) sixty-five million years, and finally we have a mass of finer subdivisions known as stages or ages. Most of these are named , nearly always awkwardly, after places: Illinoian, Desmoinesian, Croixian, Kimmeridgian, and so on in likevein. Altogether, according to John McPhee, these number in the “tens of dozens.” Fortunately, unless you take up geology as a career, you are unlikely ever to hear any of them again. Further confusing the matter is that the stages or ages in North America have different names from the stages in Europe and often only roughly intersect in time. Thus the North American Cincinnatian stage mostly corresponds with the Ashgillian stage in Europe, plus atiny bit of the slightly Carlisian doc earlier stage. Also, all this changes from textbook to textbook and from person to person, so that someauthorities describe seven recent epochs, while others are content with four. In some books, too, you will find the tertiary and quaternary taken out and replaced by periods of different lengths called the Palaeogene and Neogene. Others divide the Precambrian into two eras, the very ancient Archean and the more recent Proterozoic. Sometimes too you will see the term Phanerozoic used to describe the span encompassing the Cenozoic, Mesozoic, and Paleozoiceras. Moreover, all this applies only to units of time . Rocks are divided into quite separate units known as systems, series, and stages. A distinction is also made between late and early(referring to time) and upper and lower (referring to layers of rock ). It can all get terribly confusing to nonspecialists, but to a geologist these can be matters of passion. “I have seen grown men glow inclined with rage over this metaphorical millisecond in life's history,” The British paleontologist Richard Fortey has written with regard to a long-running twentieth-century dispute over where the boundary lies between the Cambrian and Ordovician. At least today we can bring some sophisticated dating techniques to the table. For most of the nineteenth century geologists could draw on nothing more than the most hopeful guesswork. The frustrating position then was that although they could place the various rocks and fossils, in order by age had no idea how long any of those ages were. When Buckland speculated on the antiquity of an Ichthyosaurus skeleton he could do no better than suggest that it had lived somewhere between “ten thousand, or more than ten thousand timesten thousand” years earlier. Although there was no reliable way of dating periods, there was no shortage of people willing to try. The most well known early attempt was in 1650 when Archbishop James Ussher of the Church of Ireland made a careful study of the Bible and other historical sources and concluded, in a hefty tome called Annals of the Old Testament , that the Earth had been1There will be no testing here, but if you are ever required to memorize them you might wish to remember JohnWilfords helpful advice to think of the eras (Precambrian, Paleozoic, Mesozoic, an( Cenozoic) as seasons in a year and the periods (Permian, Triassic Jurassic, etc.) as the months. created at midday on October 23, 4004B.C. , an assertion that has amused historians and textbook writers ever since. 2There is a persistent myth, incidentally—and one propounded in many serious books—that Ussher's views dominated scientific beliefs well into the nineteenth century, and that it was Lyell who put everyone straight. Stephen Jay Gould, in Time's exent Arrow, cites as a typical this from a popular book of the 1980s: “Until Lyell published his book, most thinking people accepted the idea that the earth was young.” In fact, no. As Martin JS Rudwick puts it, “No geologist of any nationality whose work was taken seriously by othergeologists advocated a timescale confined within the limits of a literalistic exegesis of Genesis.” Even the Reverend Buckland, as pious a soul as the nineteenth century here did produced, noted the Bible suggest that God made Heaven and Earth on the first day, but merely “in the beginning.” That beginning, he reasoned, may have lasted “millions upon millions of years.” Everyone agreed that the Earth was ancient. how ancient. One of the better early attempts at dating the planet came from the ever-reliable Edmond Halley, who in 1715 suggested that if you divided the total amount of salt in the world's seas by the amount added each year, you would get the number of years that the Oceans had been in existence, which would give you a rough idea of ​​Earth's age. The logic was appealing, but unfortunately no one knew how much salt was in the sea or by how much it increased each year, which rendered the experiment impactable. The first attempt at measurement that could be called remotely scientific was made by the Frenchman Georges-Louis Leclerc, Comte de Buffon, in the 1770s. It had long been known that the Earth radiated appreciable amounts of heat—that was apparent to anyone who went down a coal mine—but there wasn't any way of estimating the rate of dissipation. Buffon's experiment consisted of heating spheres until they glowed white hot and then estimating the rate of heat loss by touching them (presumably very lightly at first) as they cooled. From thishe guessed the Earth's age to be somewhere between 75,000 and 168,000 years old. This was of course a wild underestimate, but a radical notion nonetheless, and Buffon found himself threatened with excommunication for expressing it. then cheerfully repeated the assertions throughout his subsequent writings. By the middle of the nineteenth century most learned people thought the Earth was at leasta few million years old, perhaps even some tens of millions of years old, but probably not more than that. So it came as a surprise when, in 1859 in On the Origin of Species , Charles Darwin announced that the geological processes that created the Weald, an area of ​​southern England stretching across Kent, Surrey, and Sussex, had taken, by his calculations, 306,662,400 years to complete. even more for flying in the face of accepted wisdom about the age of the earth. 3It proved so contentious that Darwin withdrew it from the third edition of the book. The2Although virtually all books find a space for him, there is a striking variability in the details associated with Ussher. Some books say he made his announcement in 1650, others, in 165 still others in 1664. Many cite the date of Earths reputed beginning as October 26. At least one book of note spells his name "Usher." The matter is interestingly surveyed in Stephen Jay Goulds Eight Little Piggies. 3Darwin loved an exact number. In a later work, he announced that the number of worms to be found in an average acre of English country soil was 53,767. problem at its heart remained, however. Darwin and his geological friends needed the Earth to be old, but no one could figure out a way to make it so. Unfortunately for Darwin, and for progress, the question came to the attention of the greatLord Kelvin (who, though indubitably great, was then still just plain William Thomson; he wouldn't be elevated to the peerage until 1892, when he was sixty-eight years old and nearing the end of his career, but I shall follow the convention here of using the name retroactively). Kelvin was one of the most extraordinary figures of the nineteenth century—indeed of any century. The German scientist Hermann von Helmholtz, no intellectual slouch himself, wrote that Kelvin had by far the greatest “intelligence and lucidity, and mobility of thought” of anyman he had ever met. “I felt quite wooden beside him sometimes,” he added, a bit rejectedly. The sentiment is understandable, for Kelvin really was a kind of Victorian superman. Hewas born in 1824 in Belfast, the son of a professor of mathematics at the Royal AcademicalInstitution who soon after transferred to Glasgow. There Kelvin proved himself such aprodigy that he was admitted to Glasgow University at the exceedingly tender age of ten. Bythe time he had reached his early twenties, he had studied at institutions in London and Paris,graduated from Cambridge (where he won the university's top prizes for rowing andmathematics, and somehow found time to launch a musical society as well), been elected afellow of Peterhouse, and written (in French and English) a dozen papers in pure and appliedmathematics of such dazzling originality that he had to publish them anonymously for fear ofembarrassing his superiors. At the age of twenty-two he returned to Glasgow University totake up a professorship in natural philosophy, a position he would hold for the next fifty-threeyears. In the course of a long career (he lived till 1907 and the age of eighty-three), he wrote 661papers, accumulated 69 patents (from which he grew abundantly wealthy), and gained renownin nearly every branch of the physical sciences. Among much else, he suggested the methodthat led directly to the invention of refrigeration, devised the scale of absolute temperaturethat still bears his name, invented the boosting devices that allowed telegrams to be sentacross oceans, and made innumerable improvements to shipping and navigation, from theinvention of a popular marine compass to the creation of the first depth sounder. And thosewere merely his practical achievements. His theoretical work, in electromagnetism, thermodynamics, and the wave theory of light,was equally revolutionary. 4He had really only one flaw and that was an inability to calculatethe correct age of the Earth. The question occupied much of the second half of his career, buthe never came anywhere near getting it right. His first effort, in 1862 for an article in apopular magazine called Macmillan's , suggested that the Earth was 98 million years old, butcautiously allowed that the figure could be as low as 20 million years or as high as 400million. With remarkable prudence he acknowledged that his calculations could be wrong if4In particular he elaborated the Second Law of Thermodynamics. A discussion of these laws would be a book initself, but I offer here this crisp summation by the chemist P. W Atkins, just to provide a sense of them: "Thereare four Laws. The third of them, the Second Law, was recognized first; the first, the Zeroth Law, wasformulated last; the First Law was second; the Third Law might not even be a law in the same sense as theothers." In briefest terms, the second la states that a little energy is always wasted. You cant have a perpetualmotion device because no matter how efficient, it will always lose energy and eventually run down. The first lawsays that you cant create energy and the third that you cant reduce temperatures to absolute zero; there willalways be some residual warmth. As Dennis Overbye notes, the three principal laws are sometimes expressedjocularly as (1) you cant win, (2) you cant break even, and (3) you cant get out of the game. “sources now unknown to us are prepared in the great storehouse of creation”—but it wasclear that he thought that unlikely. With the passage of time Kelvin would become more forthright in his assertions and lesscorrect. He continually revised his estimates downward, from a maximum of 400 millionyears, to 100 million years, to 50 million years, and finally, in 1897, to a mere 24 millionyears. Kelvin wasn't being willful. It was simply that there was nothing in physics that couldexplain how a body the size of the Sun could burn continuously for more than a few tens ofmillions of years at most without exhausting its fuel. Therefore it followed that the Sun and itsplanets were relatively, but inescapably, youthful. The problem was that nearly all the fossil evidence contradicted this, and suddenly in thenineteenth century there was a lot of fossil evidence.