Why did Dr Ballard, on his journeys to photograph the Titanic, habitually play classical music during the descent and rock music on the way back up? It is unthinkable that it could have been the other way around. The idea of ‘the Deep’ is so powerful that if we listen to the word as we say it a shiver may pass through in recognition of all the associations it has jarred into resonance. By comparison, ‘heaven’ is blank and thin, even faintly unserious. ‘The Deep’ is utterly solemn. Tennyson, whose childhood on the Lincolnshire coast left the recurrence of the sea and its imagery in his poems, knew the word’s exact weight. Stately, funereal, mysterious, it spoke ultimately of loss: a steep dark bulk, time’s liquid correlative which gulps down objects, lives, all that was and will be. Sometimes it is dreamily sinister, as when he layers the ocean horizontally to intensify sheer depth and discern his ageless monster:
Below the thunders of the upper deep;
Far, far beneath in the abysmal sea,
His ancient, dreamless, uninvaded sleep
The Kraken sleepeth …*
Elsewhere, he blurs the outline of a lost friend with the geological implacability of death:
There rolls the deep where grew the tree
O earth, what changes hast thou seen!
There where the long street roars, hath been
The stillness of the central sea.†
Tennyson had read Principles of Geology and must have been struck by the passage where Lyell describes how ‘many flourishing inland towns, and a still greater number of ports, now stand where the sea rolled its waves.’* These two themes – monsters and geology – recur over and over again in the intellectual life of the mid-nineteenth century as the question of ‘the Deep’ was finally tackled by science.
*
Alexander the Great allegedly had himself lowered into the Mediterranean in a glass cage whose door was fastened with rings and chains. He judiciously took food with him, anticipating a long vigil. It was a legendary business, suitable for enhancing the heroic myth, paralleled in the twentieth century by stories such as those told during the Chinese cultural revolution of Mao Tse-Tung strolling for an hour on the bottom of the Yangtse. In Alexander’s case the things he saw were on a properly heroic scale. He observed a monster fish which took three days and three nights to swim past. Such was the insatiability of his scopic drive that, powerless inside his observation chamber, he nonetheless managed to include in his hero’s gaze the subjects of another monarch, uninvited as he was to Neptune’s abyssal kingdom. It was an exclusive as well as excluding view:
None of the men who have been before me, and none of those who shall come after me upon the earth shall see the mountains and the seas, and the darkness, and the light which I have seen …†
The glass cage was all-important. Alexander was not in that humbler but more reliable alternative, a wooden barrel with a glass spyhole. Evidently he felt it important both to see and be seen, to be recognised as Alexander the Great by the creatures of the deep. Maybe this is a characteristic of heroes, for it is also told of him that after death his body was embalmed in honey and, according to his own instructions, exhibited in a glass coffin. This must have afforded an attraction of Leninesque proportions, and it would be interesting to know if he left orders that his eyes remain open beneath the honey the better to survey his awed pilgrims even as they him.
The legend of Alexander’s descent makes plain that the depths of the sea is no place for ordinary mortals. It took a hero to confront it on anything like equal terms. Despite salvage activities, until the late eighteenth century the average European’s mental image of the sea was literally superficial, of a navigable surface above an abyss. It was a treacherous surface, obviously, being liable to spasms of hostility or the unpredictable appearance of awesome creatures from below; but a seafarer needed to know only about winds, waves and currents, and the intentions of other seafarers. Anything deeper was hidden. Yet the work of early hydrographers, the attempts of Scandinavians to correlate the supply of fish with currents, and the demands of geologists to have their theories confirmed made it inevitable that the barrier of the deep sea would be tackled. It was a barrier in more than just the physical sense, however. There was something in the very concept of the abyss which paralysed thought. There seems no other way of explaining the long survival of certain fallacies more akin to superstitions, often promoted by scientists themselves in contradiction of their own laws. Two famous examples show this: the notion of the compressibility of seawater, and the temperature at which seawater reaches its greatest density.
By the end of the eighteenth century scientists knew perfectly well that water, unlike air, can scarcely be compressed at all. Even under great pressure the density of water changes little, certainly not enough to alter its viscosity by much. To the extent that it does change, temperature is a more important factor than pressure. Yet an extraordinary theory survived this knowledge, lasting well into the twentieth century. It held that as pressure increased with depth, seawater grew more and more solid until a point was reached beyond which a sinking object could sink no further. Thus, somewhere in the middle regions of the great abyss, there existed ‘floors’ on which objects gathered according to their weight. Cannon, anchors and barrels of nails would sink lower than wooden ships, which in turn would lie beneath drowned sailors who themselves lay at slightly different levels one from another, depending on their relative stoutness, the clothes they were wearing and, quite possibly, the weight of their sins. This notion was reflected in the old saying ‘Jack will find his own level’. The popular belief was that having reached their level, bodies would forever drift and revolve in timeless suspension. After the Titanic disaster in 1912 it was reported that some of the relatives of drowned passengers had expressed dismay at the prospect of their loved ones wandering through the abyss in submarine limbo.
In the mid-nineteenth century this belief was held even by many scientists. Doubt had been voiced that the transatlantic telegraph cable would ever reach the seabed Lieutenant Maury claimed to have mapped. Might it not sink only so far, to lie conveniently above any ridges and crevasses? (‘This would be to our benefit,’ one nervous shareholder in the original Atlantic Telegraph Company wrote to a friend. ‘Yet surely the conversants’ [sic] voices, subjected to such uncommon compression, may emerge only as mouselike squeakings?’, thereby adding a further misconception of his own. Heady days for speculators, in both senses.) In an otherwise sensible book published in New York in 1844 we find:
Heavy bodies, which will sink rapidly from the surface, do at length apparently cease to descend long before they have reached the bottom; the pressure of the water being such as to cause them to remain at certain depths, varying in proportion to their weights. Thus it is that the plumb line will not act beyond a certain length, and we have no means, of course, of extending our enquiries deeper.*
This passage embodies a strange and interesting idea which reverses conventional heuristic wisdom, namely, that theory can itself make experimentation impossible. At moments like this it becomes legitimate to think about a psychic barrier to exploring the deep. A similar implication, that there are certain things best left undone and certain places it is wiser to leave untrespassed, is no doubt behind the pseudo-scientific reasons periodically advanced for the impossibility of doing them and warnings of the disaster which must befall any attempt to breach the ‘natural’ limits to human activities. It had been predicted at much the same period that speeds above that of a galloping horse would necessarily kill railway passengers. (In the twentieth century, too, ideas were dreamed up to show how any attempt to travel in space would be doomed. Arthur C. Clarke once quoted a man who had written in the 1950s to inform him there was a barrier separating the outer atmosphere from space proper, an ‘adamantine membrane’ which kept our air in. Anyone having the temerity to force his impudent way through this protection put there for our benefit by A Being Wiser than Ourselves would risk being sucked at infinite speed into outer darkness, followed by all the planet’s air.) The anxiety behind such misgivings has accompanied all technological advance. Why else the notion of the sound ‘barrier’? Those who worry about ‘breaking’ the speed of sound or infringing the depths of space are hardly distinguishable from those who, a century earlier, believed the depths of the sea could never be explored.
Any object or creature floating on the sea’s surface is already supporting with its body the weight of a column of atmosphere tens of miles high, a pressure defined as one atmosphere. To a creature accustomed to sea-level pressures, such as most human beings, this is not noticeable since his body will be in equilibrium with atmospheric pressure. The moment he descends below the waves, however, he will carry the additional weight of a column of water which, being so much denser than air, bears very heavily on his lightly pressurised body. Water pressure increases by an entire atmosphere for every 10 metres of depth. Although the human body is seven-tenths fluid, its pockets of air, its cavities and the materials and construction of many of its components make it far less dense than water. In order to prevent himself being squeezed to death beyond a certain, quite shallow, depth, a human needs to be protected by an outer casing (a diving suit or a submersible) which can resist this external pressure and permit an enclosed environment at his preferred sea-level pressure of one atmosphere. Clearly, the deeper he goes, the stronger this protective cell will need to be. The pressure at the bottom of the Marianas Trench is some 1,170 atmospheres, where each square inch of the seabed, or of a body lying on it, bears a weight of 7.75 tonnes.
The assumption that water itself could be squeezed ‘solider’ by such pressures, as a human body would, no doubt derived from Homo’s habit of seeing the physical world in his own image. This fallacious idea that water could be compressed into an impenetrable layer somewhere ‘below the thunders of the upper deep’ was remarkably tenacious although it never stopped serious attempts to take soundings at ever greater depths. Certain scientists did wonder whether the sounding line might not really be going any lower but simply be piling up in loose coils on this invisible floor like a thread of honey falling on to a plate. Samples of mud brought up were explained as the sediment which had likewise collected there over the course of millennia, presumably building up into a false bottom to the sea. It was the second misconception, however – about the temperature at which seawater reaches its maximum density – that was the more seriously and widely held and had further-reaching effects on early oceanography. It was more baffling, too, since it was blandly assumed – and could very simply have been disproved – that salt water behaves like fresh and is at its densest at 4°C. Strangest of all, the actual temperature had already been established, as Wyville Thomson later pointed out. ‘In 1833 it was ascertained that the temperature of sea water at its maximum density is – 3.67°C, and even before that it was known that sea water can be colder than the freezing point of fresh water and still remain liquid.’*
Unfortunately, the reluctance to accept what had already been scientifically determined was compounded by the inadequacy of the instruments of the day, as Sir James Clark Ross unwittingly showed on his Antarctic expedition of 1839–43. From the decks of HMSS Terror and Erebus (which only two years later were to disappear famously when Sir John Franklin took them to the Arctic to search for the north-west passage), thermometers were lowered on sounding lines deep into the South Polar ocean. When pulled up, those that had not imploded under the pressure read 4°C. What Ross did not know was that in those latitudes the water temperature drops about 1°C every 550 fathoms, a decrease which by sheer mischance happens exactly to compensate for the opposite effect of pressure on an unprotected thermometer. In point of fact his own uncle, Sir John Ross, had already found a temperature of –1.8°C more than twenty years earlier with a thermometer which must have been protected against pressure. This was in 1818, during the expedition to Baffin Bay in HMS Isabella. Sir John not only established this temperature at a depth of 1,050 fathoms but he also brought up a beautiful ‘Medusa’s Head’ starfish (a basket star) from the same depth, something which was conveniently overlooked in the following decades.
The prevailing view of the abyss was now of a vast body of water at a uniform temperature of 4°C, unmoved by either winds or currents. (Had the temperature been allowed by theory to vary between 4°C and –3.67°C, slow convection currents would have been set up.) Without movement, scientists reasoned, there could be no circulation of dissolved oxygen and no renewal of any food particles in suspension. This in turn would ensure the abyss was ‘azoic’, or lifeless, since a stagnant body of water under huge pressure, at barely above freezing point and utterly without light, could not conceivably support life.
The word ‘azoic’ was coined by Edward Forbes, who in the 1840s tried to discover where the boundary lay between the upper part of the ocean which would support life and this great ‘lifeless’ zone. Forbes was a Manx naturalist who in 1842 sailed to the Aegean in HMS Beacon to study the vertical distribution of marine animals. What he found confirmed his theory to his own satisfaction and he came home saying he considered 300 fathoms to be the absolute limit of animal life in the ocean. In fact, as Margaret Deacon has pointed out, such life is particularly sparse at that depth in the Mediterranean.* Forbes also went dredging in the Firth of Forth, taking with him the young Wyville Thomson who for a long time accepted his mentor’s ‘azoic’ theory and thirty years later would write shamefacedly:
We had adopted the current strange misconception with regard to ocean temperature; and it is perhaps scarcely a valid excuse that the fallacy of a universal and constant temperature of 4°C below a certain depth … was at the time accepted and taught by nearly all the leading authorities in Physical Geography.*
If it caused a scientist shame in the 1870s to recall the cant of his youth, it is not easy to know how to treat an episode which took place in the House of Commons nearly a century later. On 12 April 1961 the MP Hector Hughes asked the Civil Lord of the Admiralty, Ian Orr-Ewing, certain questions about recent ‘experimental missions’ beneath the Arctic ice cap by the Royal Navy submarines Finwhale and Amphion. The Civil Lord would give no details, explaining ‘It would not be in the national interest.’ His questioner shifted to the less classified ground of schoolboy physics and the following exchange took place:
| Mr Hughes: | Can the hon. Gentleman say why the water under the North Pole does not freeze while the water on the surface of the North Pole does freeze? … Is the water under the ice kept warm by the heat generated from the centre of the earth? |
| Mr Orr-Ewing: | In view of the hon. and learned Gentleman’s interest in bathing, I can understand his anxiety about where the ice forms. If he studies the physical tables, he will find that the water is most dense at 4 degrees centigrade and rises to the surface when it reaches 0 degrees centigrade and starts to freeze.† |
The ‘azoic’ theory held into the second half of the nineteenth century. When HMS Bulldog resurveyed the transatlantic route for a telegraph cable, soundings were taken down to 2,000 fathoms. When the sounding lines brought up starfish, everyone maintained that the creatures must somehow have become entangled as the lines were being pulled through shallower levels. It was only in 1860 that the theory was finally and unequivocally exploded when a section of telegraph cable was fetched up for repair off the coast of Sardinia. The cable had been laid three years earlier in more than 1,000 fathoms of water (i.e. over a mile deep) and it was found that various marine animals were encrusted on it, their anchoring filaments having worked their way into the outermost layer of insulation. It was quite impossible to argue that they had ‘become entangled’; they had quite evidently grown there. Thus it turned out that the abandoning of the ‘azoic’ theory happened neatly to coincide with the publication of Darwin’s theory of evolution.
Practically overnight the almost universal conviction that the deeps were sterile changed to intense speculation that they might actually conceal life forms as well as mineral wealth. As Wyville Thomson was to observe, ‘the land of promise for the naturalist … was the bottom of the deep sea.’ It is perhaps hard now to imagine the ferment which the scientific method was causing in the middle of the nineteenth century. In the 1860s wild speculation became common when the abyss was considered in the new Darwinian light which made necessary a complete revision of prevailing ideas about the planet’s history, about man’s position in the ‘natural’ world and about his relationship to a ‘creator’. Two fields of study, geology in general and the fossil record in particular, had an especial bearing on oceanography. In his Principles of Geology Charles Lyell had avoided tackling head-on the six-day, Genesis version of creation. Instead, he confined himself to pointing out that the Earth’s features could all quite adequately be explained in terms of the simple physical processes which were visibly still shaping it: tension/compression and erosion/sedimentation. This was elegant and satisfactory. The implications might have raised some eyebrows but few hackles since it concerned only the inanimate world of petrology. The real furore was to come a quarter-century later when Darwin made man and the animals also subject to an evolutionary process which led to notions of trial and error, sports and dead ends, casual extinctions, uncomfortable family connections and – worst of all – to the logical conclusion that Homo, far from having been perfected as Nature’s last word, must himself still be evolving. Darwin’s theory also made plain the crucial evolutionary role played by environment. Where conditions were (in geological timescales) fickle and changing rapidly, the species that survived were those which best adapted and evolved to keep pace with them. It was this idea which, coinciding with the demise of the ‘azoic’ theory of the deeps, generated speculation as to what kind of creature might have adapted itself to conditions hitherto considered inimical to life. All the factors which until so recently had indicated sterility – absence of light, intense cold and pressure, no movement – now suggested the one place on Earth in which to look for unmodified ancient creatures, ‘living fossils’. (The terrestrial equivalent was the search for the ‘missing link’, a hypothetical extinct creature midway between the anthropoid apes and man. Storybook quests such as Conan Doyle’s The Lost World grew directly out of the notion that living fossils might yet be found on dry land.)
It was as if Darwin’s intellectual leap had caused natural laws to rewrite themselves and the invisible ‘floors’, which until so recently had prevented sounding lines from reaching the deep ocean bed, all collapsed at once – like adamantine membranes – and began letting through an array of plummets, grabs, dredges, corers and other sampling devices. Now dredging expeditions began finding sea animals which resembled fossils. Specimens of a stalked crinoid, Rhizocrinus lofotensis, were brought up from the deep off Norway. No known modern coastal species of this sea lily had a stalk. This was followed by all kinds of hitherto unknown varieties of starfish and sponges from the world’s oceans and further reinforced the idea of ‘living fossils’ which would presumably be more and more archaic the further down they lived. Though completely wrong, this notion did at least give oceanography the last impetus it needed to begin the systematic exploration of the deep.
Now that the problem was no longer conceptual, the major difficulty lay in designing equipment for taking deep soundings and samples. Where sounding was concerned, it was one thing to pay out a weight on the end of a line over the side of a ship but quite another to know when it had reached the bottom, since even the thinnest sounding wire weighed a lot with 2,000 fathoms deployed. Men became expert at judging when the plummet had stopped, keeping a sensitive finger on the line as it vanished overboard. However it was done, it was a laborious process. Thomson recorded that in 1868 aboard the Lightning a ‘Hydra’ sounder was used which, weighted with 336 pounds, took 33.5 minutes to reach 2,435 fathoms off Biscay and 2 hours and 2 minutes to heave back up again with a few ounces of grey Atlantic ooze. This system was much modified in detail but little changed until the invention of sonar depth-sounding. Even forty years after Thomson, the young Boyle Somerville aboard the Penguin was using a more or less identical process. ‘Birmingham Wire gauge no. 20, galvanised’ was paid out over a 9-inch diameter wheel from a huge drum holding about 6,000 fathoms. The little wheel was connected to a counter graduated in fathoms. There was a complex system of inertia brakes acting on the big spool, automatically gripping and releasing it according to the ship’s motions, thereby maintaining a safe and even tension in the wire. The weight on the end was called a ‘driver rod’, actually an iron tube, and was supplemented by two cone-shaped lumps of cast iron. Despite the brakes on the drum the entire process had to be watched ‘like a hawk’, and in fact they lost 10,000 fathoms (nearly 11.5 miles) of wire, two driver rods and two deep sea thermometers before they were successful. Then, ‘We were the first to see land that came from a depth below sea-level which was just a little more than the height of snow-topped Everest is above it.’* The Penguin’s skipper had been on the Challenger with Thomson and related a story which showed that where certain things were concerned, oceanographers had from the beginning had a sense of the priorities. At first, he remembered, the scientists had attached bottles of beer to their sounder in order to cool them. When they came up again from the icy depths the seals were intact and the corks still in place but the contents found to be ‘the very best seawater’. This method having failed, the beer was set to cool in the samples of ooze dredged up from 2,000 fathoms. This was very cold, about 35°F, and no scientific investigations were made of the sample until the beer had reached its optimum coolness.
Pranks aside, that earlier expedition had marked the high point of nineteenth-century oceanography. At Christmas 1872 HMS Challenger had sailed from Portsmouth for what turned out to be a three and a half year voyage. At the time it was the best-equipped (at government expense) scientific expedition ever mounted. Some would argue it remains the greatest of all such voyages of discovery. One of the expedition’s specific hopes was to find ‘living fossils’, and the scientists aboard vainly sifted ton after ton of bottom samples in search of wriggling trilobites. What they did find was life in even the deepest parts of the ocean. The ‘azoic’ theory was by now officially dead, of course; yet it lingered on in vestigial form owing to the technical inadequacy of the sampling instruments of the day. That is, the expedition’s director, Charles Wyville Thomson, observed there was life both at the top and the bottom of the ocean for the simple reason that it was sustainable there. Even the deepest sediments were colonised by organisms such as worms, echinoderms and omnivorous crustaceans, so it was not surprising that abyssal and even hadal (the deepest of all; that is, over 6 kilometres) ecologies could also support highly specialised types of fish. Yet Wyville Thomson still felt sure that the oceans’ middle layer would turn out to be sterile because it lacked nutrients. Such particles as there were fell straight through it and down to the seabed. His problem lay in proving or disproving this. There was as yet no reliable way of taking samples from these intermediate zones without also catching specimens from the upper layer through which a net had to pass twice.
During this long voyage there came a reminder of another enduring myth, and in sad circumstances. William Stokes, a young sailor aboard Challenger, was killed in an accident on deck. On the day of his burial at sea, a delegation of his shipmates approached Wyville Thomson and enquired anxiously whether their friend’s body, when suitably weighted, would truly reach the bottom or, as tradition had long maintained, would float at some indeterminate depth. Wyville Thomson was able to reassure them that his remains would indeed reach the bottom. A sounding taken shortly before Stokes’s funeral read nearly 4 miles, at that time the deepest ever measured.
What would happen to the boy’s body on its long fall of over 21,000 feet? A 2-pound cannon ball would take well over half an hour to reach the bottom. A corpse, far less dense and streamlined, might take hours, assuming it was not attacked and dismembered on the way down. Just as it is impossible at any funeral entirely to suppress anxiety and not wonder, in however fleeting and censored a fashion, exactly what the worms or flames will shortly do, there must have been scientists on deck that day wondering about the effects of pressure on the late William Stokes. (It is most likely that a human body has never been retrieved from such a depth. Although corpses must have been subjected experimentally to enormous pressures to see what happens, the results are presumably buried in the files of naval research institutions.) Wyville Thomson had already written in musing manner: ‘At 2,000 fathoms a man would bear upon his body a weight equal to twenty locomotive engines, each with a long goods train loaded with pig iron.’* By now he had got his facts straight about the incompressibility of water.
Any free air suspended in the water, or contained in any compressible tissue of an animal at 2,000 fathoms, would be reduced to a mere fraction of its bulk, but an organism supported through all its tissues on all sides, within and without, by incompressible fluids at the same pressure, would not necessarily be incommoded by it. We sometimes find when we get up in the morning, by a rise of an inch in the barometer, that nearly half a ton has been quietly piled upon us during the night, but we experience no inconvenience, rather a feeling of exhilaration and buoyancy, since it requires a little less exertion to move our bodies in the denser medium.†
At some point the air-containing parts of Stokes’s body would have ruptured, principally those of his face, chest and abdomen. The head would not have burst because the cranium contains no air, only incompressible liquids, but the delicate bone honeycombs of his sinuses probably collapsed before water could leak in to equalise the pressure. Sooner or later the chest could have imploded, the broken ends of the ribs coming through the skin. Any air in the gut would probably rupture the abdomen, so if Stokes had been a flatulent boy it would in the end have been his literal undoing. The pressure would also have been likely to cause stress fracturing of certain parts of his skeleton. There might, for example, have been some splitting around the pelvic crest since the abdominal wall is highly compressible whereas the pelvis is not. The same would have applied generally to any structures of finely divided bone (i.e. not solid and thick as in the femur). Stokes would have arrived on the bottom somewhat smaller than he had been on the surface, especially if he was fat, since fat is more compressible than water. The creatures of the seabed would make short work of his flesh, of course, once they had found their way through the holes his rib-ends had poked through the canvas; yet even his skeleton would not last as long as in a conventional earth burial since bone softens in seawater as its salts are leached out by osmosis. Thus softened, the boy’s remains would have crumbled away beneath the pressure.
A vivid demonstration of what deep-sea pressure can do is shown in the experiment beloved by modern oceanographers of sending down with a piece of high-tech equipment an ordinary empty polystyrene coffee cup. It comes back in miniature, a tiny white thimble, all its insulating air cells having collapsed. Yet there seems to be a reluctance to perform this experiment with the body of an animal. I scoured the Farnella for a ship’s rat, hoping that if we could kill a brace we might send them down a couple of thousand fathoms to see what ruptured, but this piece of curiosity was greeted with cries of distaste and accusations of being a ghoul.
In all, the Challenger covered 68,930 nautical miles and at the end of three and a half years brought back so many samples of marine plants, animals, seawater, sediment dredgings and corings that it took the next nineteen years to process them. By then Wyville Thomson was dead and his place had been taken by his assistant John Murray. The subsequent report, which by 1895 had reached fifty volumes, has been described as ‘the most complete expression of man’s knowledge of the deep sea’.* Perhaps as importantly, the enterprise encouraged similar expeditions by other nations, principally the USA, France, Germany, Russia, Italy and the Scandinavian countries. Even Monaco came to hold an honourable position in marine research since Prince Albert I was himself an expert yachtsman and oceanographer who financed his own expeditions. Among his most valuable contributions was a collection of specimens from the intermediate zone which Thomson had thought might be azoic.
Part of the Challenger’s achievement was to have laid to rest various misconceptions and to have settled theoretical disputes. Prominent among the latter were post-Darwinian issues concerning living fossils and the Earth’s geological evolution. The short answer to the expectation that the deeps concealed living fossils was that they did not. What they revealed was absolute proof that even the greatest depths were neither immobile nor sterile, and that they supported species which, far from remaining unchanged for 60 million years or more, had evolved their own range of special adaptations.* In the mean time, other professional judgements were painfully exposed as incorrect. A few years before the Challenger expedition set sail Darwin’s friend and champion, T. H. Huxley, had formulated two hypotheses which became causes célèbres, one concerning a notional living fossil of the most primitive kind, the other geology.
In June and July 1857 HM frigate Cyclops, while sounding down to 2,400 fathoms, brought up some sediment samples which in due course arrived back in London for examination. Huxley, at the time Palaeontologist at the London School of Mines, had them preserved in strong alcohol and appeared to forget about them until 1868. On re-examining them after eleven years he found a transparent jelly and became convinced that this was a living slime which carpeted the deep ocean floor, ingesting ooze and forming a rich layer of protoplasm which became a food supply for other life forms. As such, he gave it the name Bathybius haeckelii in honour of the German biologist Ernst Haeckel. Haeckel had been much struck by Darwin’s theories and was preoccupied with finding a primitive organism which might provide the missing link between inanimate matter and life. The catchphrase of the day was ‘abiogenesis’ or ‘spontaneous generation’, to describe the belief that living organisms could develop from non-living matter. (At a microbiological level this was exploded by Pasteur. In the present century an updated form of the idea was floated when amino acids, the ‘building blocks of life’, were generated in the laboratory by imitation lightning discharges in mixtures of gases thought to approximate Earth’s primordial atmosphere.) Haeckel was convinced Bathybius was the basis of all evolution, the original living matter or Urschleim. Whatever else, it would have to be a subject for investigation aboard Challenger since once Huxley had found and named it everybody else seemed to be dredging up samples and it was important to establish whether this primordial slime could be found evenly distributed throughout the world’s oceans.
For two years Challenger found no Bathybius and finally the expedition’s chemist, John Buchanan, discovered that he could reproduce this jelly-like substance when he preserved bottom samples in alcohol. He came to the conclusion that this famous protoplasm was no more than calcium sulphate precipitated out of seawater by the alcohol. Thomson at once wrote to Huxley who promptly, and with immense dignity, admitted the correctness of this chemical explanation and his own error. From that moment Bathybius was dead, although several scientists tried in vain to discredit the explanation and its discoverer’s retraction.*
The second of Huxley’s hypotheses also concerned deep-sea ooze, but in a geological rather than biological context. This was his theory of the ‘continuity of chalk’ which, briefly, stated that deep-sea ooze turned into the chalk deposits found on land, so that the continents were formed of the compacted material of the seabed. The essence of this position was the belief of the day that land could only move vertically up and down, for this was long before men like Emile Argand and Alfred Wegener had proposed lateral movement and continental drift. This gave rise to a debate between those scientists who believed the ocean basins and the high continents slowly traded places, and those who thought basins remained basins and continents continents. The Challenger soon put paid to the continuity of chalk theory, too. It found that deep-sea oozes were quite distinct chemically from rock formations on land. Besides, geologists had for years been turning up shallow-water fossils in chalk beds on land, showing they could never have been formed in the deep oceans. The upshot was that no evidence was found either for drowned continents or rising ocean basins. This was a particular disappointment to palaeontologists, zoologists, botanists and others who thought they needed a sunken land bridge to explain how they were finding close correspondences between species of animals and types of geological formation in otherwise widely separated land masses. They, too, had to wait for Wegener as well as for theories of convergent evolution which explained how unrelated organisms can evolve similar shapes and adaptations in response to similar environments.
Behind this gathering of knowledge and the dispelling of misconception and superstition grew a desire to visit the deeps in person. In a way, the development of the submarine from the early twentieth century onwards was merely tantalising, since submarines were incapable of descending deeper than a few hundred feet, scarcely beyond the euphotic zone. Compared with reaching the deeps, this was the equivalent of getting a toe wet. Besides, submarines were war machines, not research vessels, and were far too big. They had the inherent problem of needing to support a large volume of air against great external pressure. This could only be achieved by massive construction, otherwise they would be crushed like a ribcage. Not until the 1930s did a true hero emerge prepared to put his trust in a piece of equipment which Alexander the Great would certainly have disdained.
This was the bathysphere, a name coined by its American inventor, William Beebe. The concept was simplicity itself. A thick-walled steel sphere with a circular entry hatch and a tiny porthole would be lowered like a plummet over the side of a ship on the end of a cable. In effect, it was an eyeball on a string. It could do nothing of itself but carry man’s sight into unseen regions. Beebe’s accounts of those early dives are in a sense laconic, even though shot through with terrifying images of the physical forces involved. The bathysphere was once sent down empty on a test dive and when hauled up was much heavier than usual. As the first bolts of the hatch were loosened needle jets of water sprayed out, showing it was partly full and under great pressure. It was clear to everyone that at some point in the loosening process the entire hatch might blow off, yet Beebe and his companion Otis Barton went on unscrewing the nuts with spanners while standing as far to one side as they could. When it finally did blow the heavy steel plate missed them both by fractions of an inch, flew the length of the deck, humming, and dented a donkey winch. Both men eventually felt the technological problems had been mastered, however, and made a historic series of dives cramped for hours in the tiny space, taking it in turns to squint awkwardly out of the peephole and dictate via telephone what they saw, while a female colleague in the ship far above took it all down in shorthand. A photograph taken on deck of Beebe emerging from the bathysphere shows the physical toll these long dives took. He is barely able to get through the tiny hole, so stiff is he with cold and cramp. There is no clutter of emergency equipment on deck, no officious bustle of rescue teams dressed in special gear; just a thin man with a lined face wearing slacks and canvas shoes being helped out of a steel ball which looks not much bigger than a large mine. In 1934 he and Barton reached the record depth of 3,028 feet off Bermuda.
When Beebe’s accounts were not laconic they were filled with the excitement of a man who knows he is seeing things which no other human has ever seen and who responds with the keenest aesthetic pleasure. ‘If one dives and returns to the surface inarticulate with amazement and with a deep realization of the marvel of what he has seen and where he has been,’ Beebe wrote, ‘then he deserves to go again and again. If he is unmoved or disappointed, then there remains for him on earth only a longer or shorter period of waiting for death …’.* Beebe and Barton did go again and again. After their record descent, Beebe observed, ‘When once it has been seen, it will remain for ever the most vivid memory in life, solely because of its cosmic chill and isolation, the eternal and absolute darkness and the indescribable beauty of its inhabitants.’† He was particularly attentive to colour and the changes associated with depth. As the bathysphere was lowered through the fathoms Beebe relayed the vanishing of the comforting, warm rays of the spectrum as the colours from red through yellow to green were progressively filtered out, leaving the rest to ‘chill and night and death’. He tried to describe what was left, a paradoxical and strange illumination which was both twilight and brilliant.
It was of an indefinable translucent blue quite unlike anything I have ever seen in the upper world, and it excited our optic nerves in a most confusing manner … the blueness of the blue, both outside and inside our sphere, seemed to pass materially through the eye into our very beings.‡
I quote Beebe because he is both scrupulous and imaginative, and his text is full of small observations which anyone who is thoughtful about the sea will immediately recognise as authentic, such as that you don’t get wet when you dive, only when you surface. He was much taken by the luminous fish that swam past his window and lamented how much more he must be missing. Alexander the Great, scopic prodigy that he was, had watched a fish so huge it had taken three days to pass. Beebe merely records sadly, ‘A gigantic fish could tear past the window, and if unillumined might never be seen.’*
Years later in 1949 Otis Barton made a descent off California which increased the world depth record to 4,500 feet, but the day of the bathysphere was done. The next step was taken by Auguste Piccard in his bathyscaphe. This device, which gave him the independence of not having to dangle helplessly on a hawser from a mother ship, was the undersea version of the balloons in which he had been setting world altitude records at the time Beebe was making his first pioneering descents. The bathyscaphe consisted of a pressurised chamber not unlike the bathysphere but slung beneath a large, lightly built tank full of petrol. Since petrol is lighter than water this was the equivalent of a gas envelope, and because the contents were incompressible there was no need for great strength and weight. Ballast took the bathyscaphe down and, once that had been released at the required depth, the flotation chamber brought it back up again. Piccard emphasised the ballooning pedigree by naming his first bathyscaphe the FNRS 2. (The original FNRS was a balloon named for the Belgian National Fund for Scientific Research which had supported the project.) Piccard’s account is more technical than Beebe’s, mainly because the engineering problems he had to solve were far more complex.† Although its manoeuvrability was very limited, the bathyscaphe was untethered and independent of a mother ship. It might very easily have stuck on the bottom without the remotest hope of rescue, particularly if its flotation tank were holed. Its inventor’s story is a triumphant record of doggedly surmounting each new technical problem as it arose. His ingenious answer to the question of how to jettison ballast was a case in point. He needed to be able to dump weight in accurately controlled amounts but the pressure outside the capsule precluded any mechanical device passing through it. Apart from the additional danger of leaks, boring holes in the steel shell (which was cast and milled in two hemispheres) would weaken it. His solution was to use steel instead of lead shot as ballast and to jettison it through a separate chute around whose circumference were electromagnets. By pressing a switch Piccard could energise the magnets outside and lock the balls solid, blocking further release.
The bravery of these men seems extraordinary now, and it would be churlish to complain that Piccard was no Beebe when it came to describing what he saw when he went down. The fact is, his brilliantly engineered invention took him down very much further. In 1960 the Trieste, the latest version of the original bathyscaphe, reached the bottom of the Marianas Trench at 10,916 metres, some 35,800 feet or better than 6.75 miles. This is as deep below the ocean’s surface as the highest-flying passenger aircraft leaving its white contrails is above it. Effectively, it was the deepest point in the oceans. Quite possibly there are places where this is exceeded by a few metres,* but to all intents and purposes man had gone as deep into the oceans as he ever would, just a century after Darwin’s The Origin of Species was first published. Since then, the technology of deep-sea descent has become ever more refined and flexible, permitting proper, if limited, exploration. As with air travel, systems have become very much safer. This is by no means to belittle the courage of men like Robert Ballard, since the possibilities for disaster are still endless, miles beneath the last glimmers of daylight and with prodigious pressures ready to slam shut the tiny bubble of living space at the first sign of a weakening rivet.
*
The pleasure Beebe took in the luminous fish he saw was mixed with wonder at this evidence of a rich and entirely alien way of life where ambient darkness was as little a problem as either cold or pressure. More than sixty years earlier when aboard Porcupine, shortly before the Challenger expedition, Wyville Thomson had noted the light given off by coelenterate fauna such as gorgonians and sea pens brought to the surface in the trawl, marvelling that it should be bright enough for him to be able to read his watch by it. On one occasion what he saw gave him a glimpse into that illuminated underworld.
The trawl seemed to have gone over a regular field of a delicate, simple Gorgonid. … The stems, which were from 18′′ to 2 ft in length, were coiled in great hanks around the beam-trawl and engaged in masses in the net; and as they showed a most vivid phosphorescence of a pale lilac colour, their immense number suggested a wonderful state of things beneath – animated cornfields waving gently in a slow tidal current and glowing with a soft diffused light, scintillating and sparkling on the slightest touch, and now and again breaking into long avenues of vivid light indicating the paths of fishes or other wandering denizens of their enchanted region.*
Much research has gone into the bioluminescence of different marine organisms, a subject made more complicated because the light has no unitary function. It seems that flashes of luminescence may be used variously as a defence, to entice prey, and as a sexual display. It may be seasonal or constant. It is even thought that some creatures may adroitly vary the wavelengths they emit, thereby using light itself as a method of camouflage. This is the same principle as the red colorations used by deeper reef creatures to make themselves look grey and stonelike, though beyond a limited depth there is little point in talking in terms of colour. The theory goes that an animal could camouflage itself by emitting low levels of light if it exactly replaced that lost by absorption on its upper surface. The light would have to be of precisely the right strength, at the right wavelengths and of the right angular distribution (since below about 400 metres the remaining light falls vertically and is no longer refracted at other angles). There is increasing evidence to support this theory, and certainly the eyes of many creatures of the deep twilight and lower zones are highly sensitive to light and to the subtlest variations in its intensity and wavelength. Animals such as squid and hatchet fish use amounts of daylight which would appear indistinguishably black to human eyes in order to regulate their vertical migrations.
The discovery that vast numbers of animals rise to the upper waters at night and return to the depths during the day was surrounded by secrecy in World War II. Three scientists experimenting with sonar aboard the USS Jasper in 1942 had found a layer in the water at between 1,000 and 1,500 feet from which echoes bounced as if it were solid. This was not made public until 1946 because it was thought an enemy submarine might take advantage of the layer by hiding beneath it. In 1945 the Scripps Institution of Oceanography found that this layer moved up at night and down during the day and concluded it must be alive. Now known as the Deep Scattering Layer, its movement varies seasonally and from place to place. It consists of huge numbers of small animals migrating punctually up and down the water column, some by as much as 1,500 or 2,000 feet. The DSL is probably the chief cause of bogus sonar contacts, and many a ship has reported ‘lost’ land lurking just beneath the waves where later investigators have found only thousands of feet of water.
The deeps triumphantly disclosed the consequences of Darwin’s ideas of natural selection in that the often bizarre colours and shapes of abyssal fauna emerged as exquisite adaptations to extreme circumstances. The ‘azoic’ theory had betrayed as nothing else the limits of understanding of the nature of life, and how erroneous all judgements were when based solely on human considerations of what might constitute a liveable environment.
Where ‘monsters’ are concerned, they may yet be found, although it is unlikely, owing to scarcity of food, that they will be from the very deepest parts of the ocean. However, if the Kraken is mythical, the giant squid is not. Huge specimens – and fragments of even huger – have occasionally surfaced. It is clear from measuring the sucker marks on dead whales that immense battles must take place in the middle deeps involving squid of a size never yet seen. The great mass of the oceans remains unexplored, even as the contours of their beds are electronically surveyed. Their waters must hide many species strange to taxonomy, but this is hardly surprising. Letting down nets here and there may catch few creatures with acute sensory equipment and evasive powers. The world a mile or more down keeps its secrets well, with neither victors nor victims necessarily leaving the least trace of their lives. As regards the deepest trench faunas, there has been relatively little recent research because most of the effort and money has been directed towards studying the vent communities around ‘black smokers’, which have the required glamour to attract funding.
As to geology, the seabed turns out to be of great use in climate modelling. It is possible to weigh the atoms of oxygen trapped in fossil shells brought up in sediment cores and determine what the temperature was when the creatures were alive. Such cores have also yielded information about monsoons and glaciation. It seems the present pattern of monsoons only started some 10 million years ago, and a theory has been put forward that they have been directly influenced by the vertical uplift of land masses (as a result, one should point out, of horizontal movement elsewhere). In the last million years alone the Himalayas have risen over 2 kilometres and it now seems likely that winds and precipitation have been directly influenced by this uplift, much as the construction of a groyne or breakwater can lead to the silting up or scouring of an adjoining bay.
‘There rolls the deep where grew the tree. …’ The last Ice Age locked up enormous volumes of water during the Pleistocene when what today is known as Dogger Bank in the North Sea emerged as land. It was boggy and forested and became full of men hunting animals with flint weapons, chasing deer and bear and wild ox among the willows and birches. None of this was known until the nineteenth century when widespread trawling started and to their surprise fishermen discovered a lumpy plateau almost the size of Holland lying only 60 feet below the sea’s surface. They inferred that this had once been land when they began netting bones and axeheads and moorlog (a kind of peat). The waning of the Ice Age, that era’s equivalent of the greenhouse effect, brought an endless close season to the Pleistocene hunt. There must have been a long, mournful period of many centuries as the ice melted and the sea level began to rise again to turn this land between East Anglia and the Netherlands into an archipelago, dozens of scattered islands with heterogeneous collections of hyenas, woolly rhinoceros and mammoth struggling for survival on ever-decreasing patches of territory. Then, at length, nothing but the deep. A mere 50,000 years ago and the forests of Dogger would have been visible from what is now the coast of Lincolnshire. Tennyson, fast in the grip of transience and loss and Charles Lyell’s bleak discoveries, had no need of them to complete his vision.
The hills are shadows, and they flow
From form to form, and nothing stands;
They melt like mist, the solid lands,
Like clouds they shape themselves and go.*
* Charles Lyell, Principles of Geology, 4th ed. (1835), Vol. I, p. 375.
† E. A. Wallis Budge, trans. of the Ethiopic version of pseudo-Callisthenes (1933).
* Anon., The Ocean, A Description of the Wonders and Important Products of the Sea, p. 17.
* C. Wyville Thomson, The Depths of the Sea (London, 1874).
* Margaret Deacon, Scientists and the Sea 1650–1900 (1971).
* Boyle Somerville, The Chart-Makers (1928).
* Susan Schlee, A History of Oceanography (1975). I am much indebted to this excellent work for many details in this and other chapters.
* The first time a deep-sea creature was found to fit the fervid category of ‘living fossil’ was in 1938 with the catching of the first coelacanth. There are good reasons for disliking the whole notion of ‘living fossils’, some of which have been noted by Stephen Jay Gould with reference to horseshoe crabs. In taking issue with the meliorist view of evolution and with the tyranny of conventional iconographies – trees and ladders – he objects most to the idea that ‘old’ necessarily means ‘primitive’ or ‘simple’, as if always to imply the superiority of Homo sapiens sapiens. In addition he says, ‘We mistakenly regard horseshoe crabs as “living fossils” because the group has never produced many species, and therefore never developed much evolutionary potential for diversification; consequently, modern species are morphologically similar to early forms’ (Stephen Jay Gould, Wonderful Life, 1990). Where the modern coelacanth is concerned it cannot be considered a ‘living fossil’ because no other members of the species Latimeria chalumnae have ever been found as fossils. Come to that, ‘no other species assignable to the genus Latimeria has been found as a fossil either’ (K. S. Thomson, Living Fossil, 1991).
* An interesting postscript has recently been added to the Bathybius story by Dr A. L. Rice at IOS, suggesting that the seasonal nature of its original collection implies that some of it, at least, could have been detritus of the spring phytoplankton bloom forming a light, flocculent ‘fluff’ on the seabed. This would explain why the Challenger failed to find samples since, being the marine equivalent of thistledown, it simply puffs out of the way of dredges and epibenthic sledges. (See A. L. Rice, ‘Thomas Henry Huxley and the Strange Case of Bathybius Haeckelii …’, Archives of Natural History 2, no. 2 (1983, pp. 169–80).
* In 1984 the Japanese survey vessel Takuyo used a multibeam echo sounder to record an extreme depth of 10,924 metres in the Marianas Trench.
* C. Wyville Thomson, The Depths of the Sea (1874).
* Tennyson, In Memoriam.