Major advances in precision clock making were also ticking along, another component in this surge of technical innovation and an important part of the scientific revolution itself, since much of what was being studied depended on accurate measurement of time—especially in relation to astronomy, navigation, and surveying. Clocks before the seventeenth century were large, crude devices that never kept anything close to true time. The minute hand wasn’t added until 1670. In 1582 Galileo had observed the timekeeping properties of pendulums, and in 1656 Dutch astronomer and physicist Christian Huygens applied this principle to clock making with notable results. In 1675 he had one of those eureka! moments, thinking of a way to regulate a clock using a fixed coiled spring. This innovation led to smaller watches (though the often contentious Robert Hooke complained that he’d made a spring-regulated clock ten years earlier) that could be used onboard ships, since calculating exact time was the crucial missing component in the search to establish accurate longitude.
Much of this new scientific activity, especially in regard to astronomy and improvements in clock making, was being driven by economic and military interests, as were Halley’s speculations on the hollow earth.
In the seventeenth century England became a true maritime power. From the time of the Restoration (1660) onward, English shippers began rivaling the Dutch, the world’s greatest traders. In the many tangled wars that bloodied the century (between 1650 and 1700, for instance, the English fought three wars against the Dutch and were allied with them in a fourth against the French), the sceptered isle was duking it out with rivals on the open seas and putting together a colonial empire with far-flung holdings the world over. (One notable addition came in 1664, when they seized New Amsterdam from the Dutch and renamed it for the duke of York.) This meant more and more ships crisscrossing the oceans. Naturally they all had to know where they were and where they were going, as any miscalculation could lose money and lives. All those sunken wrecks full of lost plunder are tribute to what was at stake.
Determining latitude was a breeze, achieved by taking an angle on the sun or the polestar. But longitude was a bitch. Theoretically the easiest way to determine longitude was to establish a universal time at a prime meridian and then compare that to local time, applying a simple formula to calculate the distance from the prime meridian. But accurate clocks wouldn’t exist until well into the next century, when John Harrison developed his famous watch and finally, after much cheap dodging on the Royal Society’s part, won the celebrated Longitude Prize of £20,000 (about $12 million today), which had gone begging for fifty years. Until then, the next best thing was fanatically detailed astronomical tables.
In the seventeenth century, astronomy was a weapon in the national arsenal. For example, in 1675 King Charles II was persuaded to okay funding for the Greenwich Observatory. He did this because the sneaky, underhanded French had built one, and he didn’t want England to be faced with an observatory gap! The first scientific institution in Great Britain, it was essentially built as a military installation. The money came from the budget of the Ordnance Department, which, as Lisa Jardine observes, was the Restoration equivalent of the Pentagon. The goal was greater accuracy and detail in astronomical charts—pinpointing the positions of the stars, the moon, and even the moons of Jupiter. Prior to trustworthy seagoing chronometers, celestial bodies were the most reliable way of determining longitude, distant clocks shining in the nighttime sky.
In 1676 twenty-year-old Halley left Oxford without graduating and eagerly journeyed to the island of St. Helena, a patch of land belonging to the East India Company located 1,200 miles west of Africa’s southwestern coast. Arriving in 1677, there he spent a year mapping the night sky, returning in 1678 to produce a catalog of the celestial longitudes and latitudes of 341 stars—the first of its kind for that hemisphere and a considerable aid to navigation. As we’ll see, navigational concerns led Halley to his theory of the hollow earth, as he attempted to explain variations in the earth’s magnetic poles.
The magnetic compass had come into use during the twelfth century; and while valuable in a general way, sailors soon found that compasses had the annoying habit of significantly deviating from true north. Worse, there was no evident pattern or consistency to the magnetic variation. The lines of the earth’s magnetism bend away from true north, and at any given place these variances themselves vary over time. Understanding the causes might lead to the ability to predict variation and thus compensate for readings that had been misleading sailors for centuries. (Another difficulty lay in New World real estate; territorial boundaries established with simple compasses caused constant legal wrangling as magnetic variation shifted.)
Here was a problem as significant as that of establishing accurate longitude.
Halley had more than a passing interest in magnetic variation. He had investigated the puzzle for years before presenting his 1691 papers and spent several years afterward at sea, primarily mapping magnetic variation in the South Atlantic. Understanding its causes promised potential long-term rewards, but detailed chapter-and-verse charts of current observed deviation were of immediate pragmatic value. His 1701 magnetic charts of the Atlantic and the Pacific were the first such published, as well as the first to connect points on the oceans with the same variance, using lines now called isogonic lines—also the first published.
He had made his first observations on magnetism as a sixteen-year-old schoolboy and continued them four years later during his long excursion to St. Helena. Magnetism was one of the great unknowns. It had been recognized as a force since ancient times, but nobody had a clue what it was. Sailors, for example, believed the powerful fumes given off by garlic somehow interfered with the proper working of the compass, and they wouldn’t allow the stuff onboard.
The earliest scientific ideas about magnetism came from William Gilbert, eventual physician to Queen Elizabeth, who in 1600 published De Magnete after eighteen years of study and experimentation. In it he suggested that the earth is a vast magnet, explaining for the first time why compasses point north. Descartes had a go at a theory of magnetism in his 1644 Principia philosophiae, involving his famous fluids and vortices, but it was as wrong as it was ingenious.
The major work on the subject was Athanasius Kircher’s 1641 Magnes, both exhaustive and a little cuckoo, a perfect emblem of the man himself. Kircher, a German Jesuit born in 1601, combined polymath erudition and intellectual eccentricity in ways far beyond those of mortal men. He is often mentioned as a candidate for “the last man to know everything,” from obscure archaic languages and literatures to the latest in science to the most fantastical absurdities then in currency, all in heaps in the measureless attic of his remarkable mind. He was, as we used to say in the 1960s, a trip. He wrote forty-four books on subjects ranging from Egyptian hieroglyphics to possible causes of the bubonic plague, constructed strange objects (including an automatic organ), and assembled in Rome what was arguably the first natural history museum.
Kircher’s Magnes, as one account describes it, “contains all that was known in his day on the subject of electricity and magnetism … filled with curiosities, both profound and frivolous. The work does not deal solely with what modern physicists call magnetism. Kircher discusses, for example, the magnetism of the earth and heavenly bodies; the tides; the attraction and repulsion in animals and plants; and the magnetic attraction of music and love. He also explains the practical applications of magnetism in medicine, hydraulics, and even in the construction of scientific instruments and toys. In the epilogue Kircher moves from the practical to the metaphysical (and Aristotelian) when he discusses the nature and position of God: the central magnet of the universe.”2
Here is the weltanschauung of a man standing astride two continents of thought, one of them sinking fast. Despite his scientific instincts, Kircher resolutely wrapped his investigations, and especially his conclusions, in the theological fabric that had dominated intellectual pursuits for hundreds of years, one sun setting and an
other rising in a single mind. The end-of-an-era quality of his work is probably why he is little known now—that and the fact that he contributed virtually no original thought to the new science. But at the time his books were widely read and discussed, and Halley was certainly aware of Magnes. (Four of Kircher’s books were listed in the inventory of Halley’s library at his death.)
Another of his books had a certain relevance to Halley’s hollow earth theory, the encyclopedic two-volume Mundus subterraneus, published in 1665 and something of a best seller in scientific circles—a work that Halley and the other Royal Society fellows would have known intimately. As Magnes compiled everything under the sun that Kircher could find or dream up about magnetism, Mundus subterraneus was a massive miscellany of knowledge and speculation about the earth’s interior that included many knockout etchings by Kircher himself illustrating his theories.
Kircher’s interest in things below stemmed from a long visit to Sicily, where in March 1638 he had close-up views as the famous volcanoes Aetna and Stromboli erupted. On returning to Naples, the enterprising priest arranged to have himself lowered into the crater of Vesuvius, active at the time, to see what he could see. One thing led to another. Nearly thirty years later, Mundus subterraneus gathered in eight hundred pages everything that was known about geography and geology, along with discourses on, for example, underworld giants, dragons, and demons; the spontaneous generation of insects from dung; mining and metallurgy; sections on poisons, astrology, alchemy, fossils, herbs, weather, gravity, the sun and the moon, eclipses, and fireworks. In addition to his writing, Kircher claimed to have performed palingenesis by restoring a plant from ashes to its original form.
Illustration by Athanasius Kircher showing pockets of interior fire scattered in a network beneath the earth’s surface. (Reprinted with permission of the Mineralogical Institute, University of Würzburg, Germany)
Amid this swirl of observed data and charming crackpottery was at least one speculation closer to truth than not: his notion about pockets of fire down below and the idea that the earth has a fiery center. If he wanted to put underworld giants down there too, he was simply carrying on a tradition that went back to Dante and beyond. His drawings of the earth’s interior were probably the first visual cross-sections attempting to suggest in a scientific way what it might be like inside.
Kircher’s thoughts regarding the world’s hydraulics take a cue from a thirteenth-century encyclopedist known as Bartholomew of England, who believed a huge whirlpool opening existed at the North Pole. Kircher envisioned the earth as a sort of vast hot water tank. Icy water from the ocean poured in at the North Pole in a great vortex, percolated southward through the earth’s interior, heated by a central fire (provided by alchemical cosmic rays), and emerged on the surface, comfy as bathwater, at the South Pole—a system of heating and circulation he believed kept the oceans from either freezing or turning putrid. As Jocelyn Godwin points out in Arktos, Kircher offers two reasons for thinking this. “The first is scholastic,” she writes, “for he states that everything in the universe has to be in motion, or else it will stagnate and die.” The second is “through analogy … with human anatomy”: it functions as a sort of digestive system. “The elements in the sea-water are extracted by this process, to be used for generation of metals. The undigested remains are then expelled at the nether end, the South Pole. As a further analogy with animal anatomy, Kircher likens the circulation of waters to the recently-discovered circulation of the blood. Thus he implies that the earth is constructed and behaves like a living creature.” His drawings illustrating this system (including subterranean lakes and rivers) are probably the earliest attempt to show global patterns of ocean circulation. Although it didn’t figure in Halley’s theory, the motif of polar openings leading inside appears again and again in the history of the hollow earth.
Illustration by Athanasius Kircher showing global patterns of ocean circulation. (Reprinted with permission of the Mineralogical Institute, University of Würzburg, Germany)
Another book about the earth’s interior that enjoyed wide readership in Halley’s time was The Sacred Theory of the Earth by Thomas Burnet. The original Latin edition appeared in 1681, with an English translation following in 1684. Stephen Jay Gould called it “the most popular geologic work of the seventeenth century.” As the new science jolted the existing Christian worldview—the biblical account of the universe—attempts to reconcile science and theology began to appear. Burnet’s Sacred Theory proved one of the most notable, a pioneering effort in creationist thinking. Burnet (1635–1715) was an English divine who served on the faculty at Christ’s College before becoming royal chaplain to King William III. As Gould wrote of him, “Burnet was a rationalist, upholding the primacy of Newton’s world in an age of faith. For Burnet’s primary concern was to render earth history not by miracles or divine caprice, but by natural, physical processes.”3
Today his ideas read like fanciful daydreams. One main purpose of his Sacred Theory was to explain Noah’s flood in a “scientific” way. No carny show miracles on God’s part after the creation, but natural (and explicable) processes at work. Burnet dismissed the idea that the flood was a local phenomenon exaggerated over time to worldwide dimensions. His reading of Scripture made him believe that the entire globe was inundated. When he calculated that the volume of water in the world’s oceans was insufficient to do the trick, he came up with a theory. Prior to the flood, the earth was unblemished as an egg:
The face of the Earth before the Deluge was smooth, regular, and uniform, without Mountains, and without a Sea… . In this smooth Earth were the first scenes of the world, and the first generation of Mankind; it had the Beauty of Youth and blooming Nature, fresh and fruitful, and not a Wrinkle, Scar or Fracture in all its body; no Rocks nor Mountains, no hollow Caves, nor gaping Channels, but even and uniform all over.
A perfect expanse. Nor did it lean slightly lopsided on its axis as it does now, but stood up nice and straight. This meant there were no seasons. At certain latitudes perpetual spring prevailed. Thanks to this eternal spring, both humans and animals had a far better time of it, as well as longer lifespans. The prelapsarian paradise!
According to Burnet, the flood threw the earth so off kilter that along with other dire results, its axis tilted, and it was goodbye, eternal spring. This idea had a certain currency in the seventeenth century. Milton expresses it in book ten of Paradise Lost (1667), though he attributes the change to a deliberate act of God, who sent angels with celestial crowbars as a wrecking crew to undo Eden by wrenching the earth’s axis askew:
Some say he bid his Angels turne ascance
The Poles of the Earth twice ten degrees and more
From the Suns Axle; they with labour push’d
Oblique the Centric Globe …
… to bring in change
Of Seasons to each Clime; else had the Spring
Perpetual smil’d on Earth with vernant Flours.
After the flood the world became as it is today—what Burnet calls a “hideous ruin” and our “dirty little planet.” In his view, how did this happen?
According to his theory, similar to one proposed by Robert Hooke in 1668, from the original liquid chaos things settled out according to their densities, the heaviest forming the core, with the “liquors” of the earth rising toward the top, rather like a global parfait. The greater part of these liquors were “volatiles,” chiefly air, but with a considerable amount of minuscule crud mixed in: “The great regions of the Air would certainly have their sediment too; for the Air was as yet thick, gross, and dark; there being an abundance of little Terrestrial particles swimming in it still.” Gradually these settled, precipitated out of the foul air, until “they compos’d a certain slime, or fat, soft, and light Earth, spread upon the face of the Waters. This thin and tender Orb of Earth increas’d still more and more, as the little Earthy parts that were detain’d in the Air could make their way to it.” Over time an even crust formed over a p
lanet largely consisting of water, like scum congealing on a cold pot of stew. He cites Psalms in support of this idea: “God hath founded the Earth upon the Seas, and to him that extended or stretched out the Earth above the Waters.”
Burnet quotes Moses in regard to what happened next: “The fountains of the great Abyss were broken open.” This was “sixteen Hundred and odd years after the Earth was made.” The culprits were three: the earth standing up so straight and unwavering on its axis, the tender crust covering the watery abyss, and the relentless sun. “Consider the effect that the heat of the Sun would have upon it, and the Waters under it; drying and parching the one, and rarifying the other into vapours.” At the hottest latitudes it would be “continual Summer, the Earth would proceed in driness still more and more, and the cracks would be wider and pierce deeper.” Eventually the sun boiled our earthly egg until it cracked. “When the appointed time was come, that All-wise Providence had design’d for the punishment of a sinful World, the whole fabrick brake, and the frame of the Earth was torn in pieces, as by an Earthquake; and those great portions or fragments, into which it was divided, fell down into the Abysse, some in one posture, some in another.” All fall down. And the world’s face today is the horrible ruin that remained after the floodwaters subsided.
Hollow Earth: The Long and Curious History of Imagining Strange Lands, Fantastical Creatures, Advanced Civilizatio Page 2