Seven-Tenths (20 page)

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:

Elsewhere, he blurs the outline of a lost friend with the geological implacability of death:

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:

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:

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: