The Story of Western Science
Page 12
But other thinkers saw the raw material differently. Isaac Newton, paying more attention to the earth’s core than to its fossils, had already speculated that the earth might originally have been a molten sphere. In that case the earth’s age could be calculated by taking into account the rate at which iron cools (always keeping in mind that large spheres retain heat differently than smaller ones, since the relationship between the quickly cooling surface and the remainder of the sphere’s mass changes). “And therefore,” Newton concludes,
a globe of red hot iron equal to our earth, that is, about 40,000,000 feet in diameter, would scarcely cool in an equal number of days, or in above 50,000 years. . . . I should be glad that the true proportion was investigated by experiment.7
In other words, if the earth had originally been molten, there was no way it was only 6,000 years old. But this was, for Newton, a “feigned” hypothesis, one that science did not yet have the tools to prove.
Newton’s colleague and sometimes competitor, the German mathematician Gottfried Wilhelm Leibniz, offered a similar speculation—that the earth had once been liquefied, like metal, and had cooled and hardened over time. This process had produced large bubbles; some of them calcified into mountains, others shattered and disintegrated, producing valleys. But Leibniz was also wary of the feigned hypothesis, and he also declined to provide a possible age for the earth.8
The age of the earth, and how the layers of the globe might be interpreted in order to find it, might have remained an open and honestly debated question. But in 1701 the bishop of Winchester, William Lloyd, added James Ussher’s date of 4004 BC to the marginal notes of the newest version of the 1611 Authorized Version of the Bible (the most widely read and influential English-language version of the Bible in print). This lent the appearance of sacred authority to Ussher’s speculation; from this point on, proposing an age of more than 6,000 years for the earth would carry with it the slur of denying scripture.
It was fifty years before another scholar dared to suggest a longer chronology. Even then, the suggestion was made in the form of fiction, and underground fiction at that.
In the 1720s the French natural philosopher Benoît de Maillet circulated, privately, a set of dialogues between an Indian philosopher named Telliamed and a French missionary about the age of the earth.* Telliamed, pointing to centuries of measurements showing that the level of the Mediterranean was dropping, argued that the whole earth had once been covered in sea, but this sea was constantly seeping into a vortex at the globe’s center. The rate of the water’s fall meant that the earth was at least two billion years old.
But this estimate need not contradict scripture: “You look upon [the question of the earth’s age] to be necessarily connected with your religion,” Telliamed tells the missionary, “though in my own opinion, the former is quite indifferent to the latter.” The study of the earth, he explains, cannot be done through the lens of faith. Rather, the planet must be examined with the objectivity that the astronomer brings to any other phenomenon:
Let us not measure the past duration of the world, by that of our own years. Let us carefully consider what presents itself to our view in this universe, this immensity of the firmament, where we see so many other stars like our own sparkling. . . . Let us imagine to ourselves what is rendered highly probable since the invention of telescopes, that if we were placed at the highest point of this distance from our earth, which we can reach with them, we should perhaps discover as many worlds above us, which would be no less distant from our view.9
Not until the earth was accepted as one heavenly body among a myriad of others could geology come into existence. And not until human years were dismissed as the measure of all things could the time frame that geology demanded be laid out.
•
In the middle of the eighteenth century, the Comte de Buffon began to build the new science.
Buffon had been born Georges-Louis Leclerc, son of a salt tax administrator. The tax man had inherited a massive fortune and used it to buy the nearby village of Buffon; this purchase made him brand-new nobility. Young Georges-Louis, sensitive over his humble origins, abandoned the surname Leclerc in his twenties and merely signed himself “Buffon” for the rest of his life.10
His family wealth allowed him to indulge his wide-ranging interests in mathematics, physics, chemistry, microscopics, and botany. He tinkered, investigated, wrote, lectured, published. By the time he was in his thirties, his impressively broad accomplishments had caught the eye of the French court. In 1739 he was given the post of curator of the royal gardens, in charge of expanding and improving both the gardens and the zoo inside it; he held this position for the rest of his life.
Buffon’s duties as curator tended to focus his wide-ranging interests, more closely, onto the earth and its living systems. In 1740 he announced the beginnings of a massive encyclopedic work, a fifty-volume Natural History. It was a hugely ambitious expansion of the project that Aristotle had undertaken in the History of Animals, encompassing not just animal life, but botany as well. And as Buffon began to work, he realized that he could not begin with either. “The general history of the earth,” he wrote, at the very beginning of his project, “ought to precede that of its productions.”11
So the first volume of the Natural History, General and Particular deals with the globe: its internal structure, its “form and manner of existence,” and its history. Buffon proposed to treat these things scientifically, inductively, Baconically. He rejected any explanation that relied on a single extraordinary event in the past, one that could be neither observed nor repeated, as “unstable” and “constructed on tottering foundations.” (Here, Buffon had in mind a popular theory, proposed by the mathematician William Whiston, that the present form of the earth could be explained by a primeval collision with the tail of a comet.)12
Instead, Buffon insisted that the science of the earth must adopt, as causes, only physical processes that can still be observed: the movement of water, the gradual cooling of heated substances, the erosion of soil.
I speak not here of causes removed beyond the sphere of our knowledge, of those convulsions of nature, the slightest throe of which would be fatal to the globe. The near approach of a comet, the absence of the moon, or the introduction of a new planet into the system, &c. are suppositions upon which the imagination may rove at large. Causes of this kind will produce any effect we choose. From a single hypothesis of this nature, a thousand physical romances might be drawn, and their authors might dignify them with the title of Theory of the Earth. . . . I reject these vain speculations: They depend upon mere possibilities, which, if called into action, necessarily imply such a devastation in the universe, that our globe, like a fugitive particle of matter, escapes our observation, and is no longer worthy of our attention. But, to give consistency to our ideas, we must take the earth as it is, examine its different parts with minuteness, and, by induction, judge of the future, from what at present exists. We ought not to be affected by causes which seldom act, and whose action is always sudden and violent. These have no place in the ordinary course of nature. But operations uniformly repeated, motions which succeed one another without interruption, are the causes which alone ought to be the foundation of our reasoning.13
So, what “uniformly repeated” operations might have shaped the earth? With a nod back to Newton, Buffon proposed that the planet had begun its life as a molten globe, slowly cooling toward its present temperature.
Granted, he could not observe this particular bit of the earth’s past with his own eyes. But temperature readings of the earth’s surface and deep mines clearly showed that the core was hotter than the surface, and this could be explained through a physical process that could be repeated again and again: Buffon heated iron spheres of different sizes until they glowed white, and then measured the time it took them to cool. Then he extrapolated those results to a body the size of the earth and concluded that the initial cooling of the globe had begun to take place 74,8
32 years before. Privately, he thought that an even longer time frame was probable—perhaps as long as three billion years (which is not so far off from the contemporary estimate of 4.57 billion).14
Laying out these theories in Volume 1 of the Natural History, Buffon simultaneously rejected the possibility of extraordinary divine intervention in the earth’s past and contradicted Ussher’s chronology. The book was an eighteenth-century best seller. Copies sat on the tables of well-educated men and women all over France, England, Holland, and Germany. Prominent members of the French Academy of Sciences repeatedly attacked Buffon’s conclusions. The Faculty of Theology in Paris carried on a long and suspicious correspondence with him over his understanding of Genesis.15
Buffon read the correspondence, but his commitment to his hypothesis merely deepened. Thirty years later, when he published a series of corrections and supplements to the existing volumes of the Natural History, he included a more detailed explanation of the stages of the earth’s formation, divided into seven periods:
First Epoch
The earth begins to cool.
Second Epoch
The earth solidifies.
Third Epoch
Water covers the earth.
Fourth Epoch
The waters begin to recede and volcanic activity begins.
Fifth Epoch
Elephants and “southern animals” inhabit the warm north.
Sixth Epoch
Continents separate.
Seventh Epoch
Human life begins.
These “Epochs of Nature” were the first “deep time” chronology of the earth—a phrase coined, centuries later, by John McPhee to describe the entirely different time frame (a million years are as a day) used in the study of geology.
The Epochs of Nature chronology was a bit startling to Buffon’s English translator, William Smellie—a little too un-British for his taste—so he abridged that particular section of Volume 9. “As this theory, however it may be relished on the Continent, is perhaps too fanciful to receive the general approbation of the cool and deliberate Briton,” he explained in a translator’s note, “the translator has been advised not to render it into English.”16
But Buffon made no apologies. His insistence that no extraordinary events be used as explanation—the first principle of geology—had led him, inevitably, to the second: the history of the earth was a long, long one.17
To read relevant excerpts from the Natural History, General and Particular, visit http://susanwisebauer.com/story-of-science.
GEORGES-LOUIS LECLERC, COMTE DE BUFFON
Natural History, General and Particular
(1749–88)
Volume 1 consists of only two major sections: Chapter One, “The History and Theory of the Earth,” which lays out all of Buffon’s theories about the earth’s formation, and the very long Chapter Two, “Proofs of the Theory of the Earth,” divided into nineteen “articles” that provide detailed arguments and experimental support. The first chapter is worth a close and careful read; you may wish to skim the second.
Volume 9 contains numerous additions and supplements to different sections of Volume 1. You need only read the section titled “Facts and Arguments in Support of the Count de Buffon’s Epochs of Nature: Of Giants, of the Glaciers, of the North-East Passage, concerning That Period When the Powers of Man Aided Those of Nature.”
William Smellie’s translation remains the only English version; it is readable and entertaining, but remember that his section on the Epochs of Nature is a paraphrase. It can be read in numerous free e-book versions, but the easiest to find is hosted by the University of Michigan’s Eighteenth Century Collections Online (see http://susanwisebauer.com/story-of-science for a live link).
Georges-Louis Leclerc, Comte de Buffon, Natural History: General and Particular, trans. William Smellie, vol. 1 (e-book, 1780, no ISBN).
Georges-Louis Leclerc, Comte de Buffon, Natural History: General and Particular, trans. William Smellie, vol. 9 (e-book, 1785, no ISBN).
* * *
* Church authorities probably noticed that the name Telliamed was merely “de Maillet” printed backward, but we have no record of their reaction.
FOURTEEN
The Laws of the New Science
Two different theories are proposed as explanations for the earth’s present form
The production of our present continents must have
required a time which is indefinite. . . . We find no vestige
of a beginning, no prospect of an end.
—James Hutton, Theory of the Earth, 1785
Thus, life on earth has often been disturbed by terrible events.
—Georges Cuvier, “Preliminary Discourse,” 1812
James Hutton, son of a wealthy Scottish landowner, was a born dabbler—which was exactly what the new science needed.
In 1740, at age fourteen, Hutton went to the University of Edinburgh to study Greek and Latin. He abandoned the classics to try his hand at chemistry, left school altogether and apprenticed himself to a lawyer, gave up the law at twenty-one to study medicine in Edinburgh, wandered off to Paris to specialize in anatomy, finally finished his medical degree, and then decided that the life of a doctor wasn’t for him. Instead, with the help of a friend, he started a company that produced the industrial chemical known as sal ammoniac. The company was successful, but before long Hutton left its management to his friend and decided instead to run the family farms.
He experimented with agriculture; he joined the Philosophical Society of Edinburgh and presented papers on botany, mineralogy, and artillery; he carried out chemical experiments; he visited salt mines, hiked into mountains to examine geologic formations, researched the production of coal. “Free from the interruption of professional avocations,” writes his friend and biographer John Playfair, “he enjoyed the entire command of his own time, and had sufficient energy of mind to afford himself continual occupation.”1
This sort of wide-ranging interest, combined with a private income that made earning a living unnecessary, was a prerequisite for the study of the earth—a field that still had no university chairs, no definition, no borders, no commonly accepted name. Buffon had called himself a “historian”; his fellow investigators of the planet called themselves astronomers, mathematicians, natural philosophers, gentlemen. Hutton himself spent the first half of his life bouncing among the identities of chemist, manufacturer, and farmer. He didn’t publish his first study until the age of fifty, a pamphlet with the scintillating title Considerations on the Nature, Quality, and Distinctions of Coal and Culm.* It was not exactly a best seller (“very ingenious and satisfactory,” Playfair assures us, “though, perhaps, considering the purpose for which it was written, it is on too scientific a plan”), but it reveals Hutton’s slowly focusing interests. Increasingly, he was studying the composition of the earth itself.2
The year after Hutton’s pamphlet appeared, the Swiss mathematician Jean André Deluc gave a name to the science of the earth.
For some years, Deluc had been carrying on a correspondence with Queen Charlotte of England and, as socially ambitious thinkers were prone to do, had collected the letters for publication. The first volume (there were a lot of letters), published in 1778, was titled Physical and Moral Letters on the Mountains and on the History of the Earth and Man. Deluc was a devout Protestant, preoccupied with reconciling his theories about rock formation and soil strata with the Genesis account (he disagreed strongly with Buffon’s chronology, preferring an age of about 10,000 years for the planet). “These letters,” Deluc begins, “are only an outline of a Treatise on Cosmology.” And then, in a footnote, he laments the inaccuracy of the term: “I mean here by cosmology only the knowledge of the earth, and not that of the universe. In this sense, ‘geology’ would have been the correct word, but I dare not adopt it, because it is not in common use.”3
Despite his disclaimer, Deluc continued to use the term. The Letters grew in popularity, and the word “geo
logy” gained currency. The study of the earth still had diffuse borders, mingling with theology and biblical studies on one side, physics and astronomy on another, metallurgy and chemistry on a third; but at last, it had a label.
In 1783, six years after the publication of his pamphlet on coal, Hutton finally assembled his evolving geologic theories into a major public presentation. The Philosophical Society of Edinburgh had just merged with the brand-new Royal Society of Edinburgh, dedicated to the study of both philosophy and natural sciences; anxious to support the new institution, Hutton agreed to give a paper on the “terrestrial system.” “The institution of the Royal Society,” Playfair explains, “had the good effect of calling forth from Dr. Hutton the first sketch of a theory of the earth, the formation of which had been the great object of his life.”4
Hutton was now fifty-seven years old. He had become a “skilful mineralogist” and had “examined the great facts of geology with his own eyes”; he was “eminently skilled in physical geography” and in chemistry; he had read widely in natural history. He had put all of these skills to use in investigating the nature of the earth and its systems, but until now, he had shared few of his ideas with others.5
On March 7, 1785, the first part of his presentation was read out to the Royal Society by one of his friends; Hutton himself pleaded illness (possibly overcome by nerves). “The first part of his Discourse,” the minutes of the Royal Society record, “contain[ed] an Examination of the System of the habitable Earth, with regard to its Duration and Stability.” A month later, at the society’s April meeting, Hutton himself recapped his March presentation and then read the rest of the paper.