boat in the summer of 1785, he ruminated with precision and wisdom on Sundry Circumstances Relating to the Gulph Stream — a document of such intellectual richness that it is easy to see why this most unforgettable of men went on to invent such wonders as the lightning rod, bifocal lenses, lending libraries, a superior kind of fireplace,23 and the underlying principle behind the glass harmonica.
The letter, to a French academician and friend named Alphonsus le Roy, is quite stunning, fascinating at every line. The Gulf Stream does not appear until halfway through - and by the time of getting down to writing his thoughts about it, Franklin had already offered to his friend a meandering dissertation on the design of ships’ hulls, on the possible use of propellers to steer balloons, on the most common causes of accidents at sea and on the kinds of foodstuffs best stowed for long ocean voyages (almonds, rusks, lemons and “Jamaica spirits” foremost among them).
But then came the Gulf Stream moment, when Franklin reminded le Roy that a decade before, he had been America’s first postmaster general, and colonial postmaster before that, and that this was when he first fully apprehended the North Atlantic’s most unusual phenomenon of the time:
About the year 1769 or 70, there was an application made by the board of customs at Boston, to the lords of the treasury in London, complaining that the packets between Falmouth and New York, were generally a fortnight longer in their passages, than merchant ships from London to Rhode-Island…. There happened then to be in London, a Nantucket sea-captain of my acquaintance, to whom I communicated the affair. He told me the difference was that the Rhode-Island captains were acquainted with the gulf stream, which those of the English packets were not. We are well acquainted with that stream, says he, because in our pursuit of whales, which keep near the sides of it, but are not to be met with in it…. I then observed that it was a pity no notice was taken of this current upon the charts, and requested him to mark it out for me which he readily complied with, adding directions for avoiding it in sailing from Europe to North-America, I procured it to be engraved by order.
This stream is probably generated by the great accumulation of water on the eastern coast of America between the tropics, by the trade winds which constantly blow there. It is known that a large piece of water ten miles broad and generally only three feet deep, has by a strong wind had its waters driven to one side and sustained so as to become six feet deep, while the windward side was laid dry. Having since crossed this stream several times in passing between America and Europe, I have been attentive to sundry circumstances relating to it, by which to know when one is in it; and besides the gulf weed with which it is interspersed, I find that it is always warmer than the sea on each side of it, and that it does not sparkle in the night.
Franklin then helpfully drew a map - a map somewhat short on both accuracy and elegance, but one that heralded a new field of oceanic cartography and by extension helped inaugurate the entirely new science of oceanography.
4. WRITING THE SEA
This calling, as its curious name suggests - oceanography, the writing of the ocean - was at least in its early days something of a fugitive science: for how could it be possible to write of a body of water, especially deep water beyond land, an entity without visible coasts as reference points and no detectable seabed below? It was like trying to describe the invisible mass of air in a room — a task rather beyond the imaginative and descriptive powers of the time.
It’s not surprising that of the graphical sciences, oceanography was so late in being born. Geography and hydrography, the descriptive analyses of bodies of land and water, were disciplines both created in the sixteenth century; it was not until the middle of the eighteenth century, two hundred years later, that there was sufficient confidence within the academic community to name a similar study that would be called oceanography. Matters might have been simpler had the science been called oceanology, but it never was, and now only the Russians use the term.
On some levels the study of the sea had obvious features that were well worthy of study. There were the zoological aspects — the fish, swimming mammals, and seabirds and other animals both hugely exotic and vanishingly small to catch and record and classify. There were matters botanical: the existence of floating and sunken ocean plants - Sargasso weed in immense quantities in the centre of the gyre of the North Atlantic, kelp banks around islands in the south, and a thousand other pelagic and benthic pieces of botany besides. There was a unique maritime meteorology, too: there were ocean winds in particular to record, in their variety and persistence — trades wafting steadily from the north-east, westerly gales powering the fierce climatic tantrums of the north, and then the fitful and skittish baffling airs around the equator, which were given the name of the tantrums’ literal antithesis, the doldrums. There were the dangerous circulations of the wind, too - hurricanes, waterspouts, typhoons, cyclones. There was ice and snow, and floes and tabular icebergs. And there were maritime curiosities — St. Elmo’s fire, mermaids, the Bermuda Triangle, sea serpents, giant squids.
There was all of this - but each one turned out to be merely peripheral to the ocean itself, in much the same way that the discovery of a new land mammal would be considered peripheral to geography, and the realisation of the ferocity of the harmattan wind incidental to the study of oasis formation in the Sahara. Oceans have their own very peculiar physical attributes - a list of inherences and essentials that at the very least would include such matters as the topography of the sea’s invisible underneath, the temperature and chemistry of the water, and the movement of the ocean’s currents and its tides. And early scientists did indeed notice and inquire: in the seventeenth century alone we had Robert Boyle writing on the sea’s salinity, Isaac Newton offer ing his views on the causation of tides, and Robert Hooke — the famously ill-tempered polymath and philosopher who is better known for establishing the principles of elasticity, inventing sash windows, championing microscopy, first seeing Jupiter’s Great Red Spot, and creating an elegant escapement mechanism for watches - designing a host of devices and methods that might be used for research into the deep seas.
…
So scientists did eventually begin to focus their attentions, to fathom the unfathomable, and they did begin to come to grips with the immensity of the challenge posed by such a vastness as the Atlantic. They did so especially in Victorian and Edwardian times, a period of both British and American history when the stupendously difficult often seemed unusually possible; this was a time when unravelling the immensity of an ocean looked only marginally more difficult than, say, the cataloguing of all the earth’s creatures, or the corralling between hard book covers of all the words of the English language, or the building of a transcontinental railroad, or the construction of a sea-level canal between the Atlantic and the Pacific.
Fame in the early days belonged to the explorers, those hunting for land and territory and tangible acquisitions, rather than to students of the ocean itself. Bold adventurers like James Cook, Sir John Ross, the Comte de la Pérouse, Robert Fitzroy, and the Chevalier de Bougainville are still remembered and memorialised in capes and straits and islands around the world - while the very earliest true oceanographers have largely faded from memory. Who now remembers James Rennell, for instance, a young sailor from Devon, who first came upon the Atlantic proper on a long-sea trick from military service in Bengal? There is today only his tomb, a scattering of long-forgotten books, and the name of a lecture theatre at Britain’s National Oceanography Centre in Southampton. Yet he was a properly heroic figure, of the mould of Cook and la Pérouse, the kind of seaman who would do whatever was necessary in the pursuit of his calling. While leading a team in the survey of Bengal he had almost his entire arm sheared off at the shoulder during an attack by sabre-wielding tribesmen, and then had his original maps of India stolen by pirates off Calcutta, yet persisted in acquiring new knowledge of the sea, in spite of it all.
Rennell’s oceanic achievements began in 1777 when he came home by sea — fathering a daughter who was to be born on the quintessentially Atlantic oceanic island of St Helena, where Napoleon would later be exiled - and en route became captivated by the Atlantic currents that his vessel was compelled to cross, and then by ocean circulation generally. He