Last summer, despite the rain, our national life was enlivened not only by the Olympics, but also by the Queen’s jubilee. One of the things that struck me during the many events was the prominence accorded to the Thames. One of the major events of the Jubilee was the Thames pageant, in self-conscious reference to Canaletto; the river hosted the Olympic rowing and acted as a stunning backdrop for views of the equestrian events at Greenwich; and the Paralympic opening ceremony had a decidedly watery theme. The Thames has always been, and remains central to the physical and conceptual life of the capital. And yet, given that it’s a big, navigable waterway it seldom appears in the story of the longitude problem. One notable exception would be the Harrisons’ complaint in 1767 that Nevil Maskelyne had transported their timekeepers by land to Greenwich, rather than by boat, causing them to be ‘broke to Pieces.’[1]

Such questions about the physical negotiation of metropolitan space in solving the longitude problem are something that I’m going to consider when I take up the Caird Fellowship at the National Maritime Museum next year. I was given a helping hand recently when I accompanied my undergraduate students on a walking tour of eighteenth-century London with Dr Larry Klein. We were lucky enough to be given access to the Royal Society of Arts which still inhabits its original Adam building by Embankment. The Great Room at the RSA is decorated with murals by James Barry which show The Progress of Human Knowledge and Culture (all of which you can see online thanks to the ‘Your Paintings‘ project). Barry started these in 1777 and they were first exhibited in 1783. The series features six murals showing the progress from Orpheus to Elysium, or the State of Final Retribution. I was excited to see that Barry’s pantheon of ‘great and good men of all ages’ includes Hogarth and Swift among many others.

More interestingly, though, the penultimate painting in the series Commerce, or the Triumph of the Thames, shows Father Thames steering his path to commercial triumph with the rudder in one hand and compass in the other. His bark is carried by ‘the great navigators’: Sir Francis Drake, Walter Raleigh, Sebastian Cabot, and our own longitude proponent Captain James Cook (his portrait is clearly copied from the Nathaniel Dance-Holland portrait now at the NMM). Given that Cook had only returned from his first voyage on the Resolution the year before Barry was given the commission, and the Endeavour voyage had only returned in 1771 this shows the speed with which Cook’s skills at navigating, aided notably by Kendal’s copy (K1) of Harrison’s timekeeper, quickly made him a recognised ‘national treasure.’

Looking up at Cook, I was reminded of another painted paean to national maritime success further down the river: the Painted Hall at Greenwich Old Royal Naval College, completed by Sir James Thornhill in 1714 (also a notable date for longitude as we know). Richard Johns pointed out to me that the figures behind the balustrade over the entrance to the lower hall include Astronomer Royal John Flamsteed observing the sky through his telescope to create the infamous star catalogues Historia coelestis necessary to establish the lunar distance method of finding longitude. The move over 70 years from Thornhill’s Flamsteed in Greenwich to Barry’s Cook by Embankment shows us not only the slow embedding of accurate chronometers as a rival solution to celestial observation for finding longitude at sea, but also the way that the problem and its proponents moved from royally patronised baroque Greenwich to the commercial, sublime environs of the RSA in the West End. The Thames is there in the story, but perhaps not in the way we would expect.

One of history’s coincidences allows me to use this title with impunity. One slight admission, of course, is that I’m talking about a different John Harrison. It was, however, a John Harrison who was working in the 1760s and who really was an early practitioner of lunar distances at sea.

This John Harrison, about whom disappointingly little is known, sailed as purser on HMS Dolphin’s circumnavigation of 1766-68 under the command of Samuel Wallis. What we do know is that he had an interest in astronomy and mathematics and made accurate determinations of the positions of islands discovered during the voyage. These included Tahiti, which Wallis named King George’s Island after it was first sighted in June 1767 (the Dolphin being the first European vessel to do so). Wallis noted in his journal that Harrison had established the island’s position by, ‘taking the Distance of the Sun from the Moon and working it according to Dr Masculine’s Method which we did not understand’ (Harrison presumably had a copy of Maskelyne‘s 1763 work on lunar distances, The British Mariner’s Guide). This was a fortunate discovery, as the island was in the region that Maskelyne had prescribed as favourable for observations of the next transit of Venus, due in 1769. Indeed, this was why Cook was sent to Tahiti on his first circumnavigation of 1768-71. On that voyage, Cook judged that Harrison’s position had been correct to within half a degree, which sounds pretty good.

Spending a morning at Cambridge University Library a few weeks ago, I came across an interesting related document. This was a letter from the same John Harrison to William Wales, dated May 1787 (RGO 14/187 item 13). Evidently Wales had been hoping to get more information about some eclipse observations made during the Dolphin‘s voyage and was hoping Harrison could add something. Sadly, all Harrison could say was that, ‘I am really ashamed to say I have not a paper by me relative the Voyage you mention, having lost every mathematical Book & paper I was master of’. Harrison does, however, confirm that all the observational results given in the surviving logs were ‘per Quadrant’, meaning that they had not been corrected for parallax and other errors. Harrison and his fellow mariners were clearly happy to let others do the tedious mathematics of reducing the observations, which was also one of the downsides of the lunar distance method, as Harrison presumably knew well from his longitude determinations.

Today is National Poetry Day, which has ‘stars’ as its theme this year, so it seemed rather appropriate to offer up a ‘poem’ (more or less) that was published in Lloyd’s Evening Post in 1764 (in the edition for September 12-14). The poem is about the 1763-4 sea trials to Barbados to test John Harrison’s sea watch (H4), Tobias Mayer’s latest tables for determining longitude by lunar distance, and Christopher Irwin’s marine chair for observing Jupiter’s satellites.

I’ve not included the footnotes from the original, but it’s a nice summary of at least one person’s view of what was going on at a crucial time for the history of longitude at sea:

The TRIPLE-SCHEME for finding the LONGITUDE at SEA, truly stated: Or, REMARKS on Mr. HARRISON’S TIME-PIECE, and late VOYAGE to BARBADOES.
Humbly addressed to the PUBLIC.
By the PALLADIUM AUTHOR.

To aid true judgment, which he thinks no crime,
He thus, for shortness, makes remarks in rhime.

Was e’er this Watch’s equal motion prov’d.
From Stars revolving, uniformly mov’d?
It’s gain in eight days by th’unequal Sun,
Proves not it’s equal gain in ev’ry one:
Nor does it’s gain or loss in eight days space,
Prove the same gain or loss in diff’rent place;
Without which equal motion first be shown,
No Longitude can certainly be known.
– Unequal, if it goes too fast or slow,
The Longitude, in error, must be so.
Various effects, it’s equal pace with-hold.
Shocks, gravity, wet, dry, and heat and cold;
Sometimes too slow it goes, and then too fast,
That Longitude, by chance, is found at last.
– How vain prediction, from each Port, accords
With Longitudes, as taken on mens words!
As those and Latitudes are dark or clear,
At Ship and Port, their distance will appear;
For Longitude for nothing ever serv’d,
But where the Latitude was well observ’d,
From both we shew how far the Port’s a-part,
The Navigator’s, not Time-keeper’s art.
The Seaman in the Latitude steers right
Due West or East until his Port’s in sight;
Then running three leagues off, and lying to
‘Till morning light, he hits the place most true;
As, in our voyage, we were us’d to do.
So, in return, another might behold,
And make the Lizard, as the brig foretold.
But as to what was done at Surry-stairs,
The public must be judge from what appears;
The Watch examin’d with a friend’s regard,
Was found within the Longitude-reward:
– Tho’ this, and others made, must go the same,
On ev’ry voyage — else the project’s lame!
– If such a Watch will time, at home, decide,
The time, on board, another must divide,
From day to day be often rectified.
The diff’rence of which times, when you descry,
Is the Ship’s Longitude to ev’ry eye.
But a Watch-maker must with these be sent,
To keep in order, or cure accident:
For, if these miss the Longitude at Sea,
(While num’rous Ships, for num’rous Watches pay)
The Nation’s care and cost are thrown away!
But, if you more prefer the Lunar scheme,
As Maskelyne, and Speculatists seem;
Some gaping for the mammon more than praise,
Exciting wonder, as our mirth they raise!
Two minutes, in degree, if these mis-spy,
(And who can peep out Latitude so nigh?)
Two miscompute-twice two, in time, those crost,
Then all their credit, time, and gain, are lost!
– But rivals, will each other still offend,
And for a shadow often will contend;
Each vying with the other to be great,
And each one’s scheme the other wou’d defeat!
See Irwin’s Chair exalted for a while,
O’erpower’d by interest, now is in exile!
Tho’ recommended by a noble Lord,
To whom it truth, and pleasure did afford.
An easy, cheap, and certain, simple thing,
That can’t above two minutes error bring;
As Jove‘s first Satellite will give you proof,
Whose known Eclipses are seen oft enough;
Which observations, when improv’d with care,
To thirty miles will tell you where you are.
– But Truth and Fashion vary like the Times,
Virtues to-day, to-morrow may be crimes!
And what avails it Art or Truth to know,
Without a Friend in Pow’r to prove it so!

Although the longitude story is typically dominated by the development of marine timekeepers and the lunar distance method, we need to spare a thought for good old dead reckoning – estimating a ship’s position by regularly noting its speed and heading – which, even today, is part of the routine. This was certainly also true in the 18th and 19th centuries and so improvements to dead reckoning were of interest to the Board of Longitude, particularly once its remit expanded in 1774 to include general improvements in navigation. Among its archive, therefore, are quite a number of proposals to improve this most traditional form of wayfinding.

What’s a bit less common, however, is to have a surviving instrument, in particular relating to a proposal that was not taken up in any great way.

This one, from our collections at Royal Museums Greenwich (museum number NAV0730), is a log recorder – ‘Higginson’s Log’, as it says on the side – intended to record a ship’s speed by measuring the pull (against a spring) of a rope attached to a chip-log trailed behind the ship.

What’s nice is that we can link this instrument to a proposal from 1828 that survives in the Board of Longitude archive. The proposer, Francis Higginson, describes himself as the ‘inventor of a variety of instruments and the author of Manderville, Moubray, Waterloo etc.’.  Of these, the only one I’ve identified so far is Manderville; or, The Hibernian Chiliarch, on the title page of which he also describes himself as ‘Late Commander of His Majesty’s Cutter Lynx’. This also tells us that he had been an insolvent debtor in 1825, when his petition was heard at the Court for Insolvent Debtors in Lincoln’s Inn Fields, London on 29 July.

Novelist he may have been, but I have to say that his proposal to the Board of Longitude manages to be both cryptic and tediously long-winded – in part, I think, in his attempt to intrigue the Board without giving his secrets away. What he wants, he says, is to show his device in person. The one bit I did rather like was his point that dead reckoning is essential around the British coast, ‘considering, the nature of our climate; as in fact, cloudy weather, accompanied by dense fogs, may almost be deemed, one of the prognostics attending, an approach, to the British Channel, during the winter season’. It’s the sort of weather in which observations to determine local time from the sun (which you need to do even with a chronometer) would be impossible, and so an additional way of determining one’s position would be essential.

Sadly, the Board was not impressed enough to take Higginson’s ideas further and (coincidentally) was wound up the same year.

Yesterday I had the unexpected pleasure of seeing some of our work make its way onto the stage. Some time ago, a couple of us from the Museum were asked for some advice by the Waxwings Theatre Company for a play called Tangent in which mathematics – including the problems of learning navigation in Nelson’s navy – is the focus.

I was impressed by how much they managed to work into the show, including lunar-distance theory, as well as the imaginative ways in which an early 19th-century naval vessel was evoked, in particular a pair of dividers standing in as a sextant. And you’ll be glad to hear that the midshipman’s use of lunars saves the day as his ship tries to get home from the Baltic.

There’s a couple of days left so do go and see it – you’ll believe trigonometry can be poetic!

I have recently been working on a small display at the Royal Observatory (opening next month) called Measuring the Universe. Despite being small-scale the topic is – in every sense – vast. The Observatory’s Public Astronomer, Marek Kukula, and I are trying to cover the history of measurements of the scale of the solar system, the distance to the nearest stars, the space between galaxies and to the Cosmic Microwave Background. This takes us from the Earth to the edge of the known universe, and from Greeks to researchers today.

I have been focusing on the story of measuring the Astronomical Unit, that is the distance between the Earth and the Sun, and mainly on the use of the rare astronomical phenomenon of the transit of Venus to measure solar parallax. In 1761, 1769, 1874 and 1882 there were a huge number of observations made, across the world, motivated by the hope of establishing a scale for the workings of the Newtonian solar system, thereby improving astronomical theory and predictions, but also by a range of practical, geographical, national and imperial interests. A useful list of historic transit observations can be found here.

There are three good reasons for turning over half of the exhibition to this story: 1) there is a transit of Venus happening this June, probably the last opportunity to see it in any of our lifetimes 2) the Royal Observatory and its staff were much involved in the effort of organising expeditions, observing transits and reducing the data to produce results and 3) transit observations required overseas expeditions, as measuring solar parallax required observations from different latitudes, which involved maritime navigation, exploration and a host of themes of interest to the ROG, the NMM and me, as curator and a member of the Longitude project team.

Distilling down a story that includes Edmond Halley, Nevil Maskelyne, James Cook, George Airy and a host of the ROG’s assistants – to indicate just a few on the British side – has been challenging, to say the least! The main mission is to convey an idea of the method, the amount of organisation and effort required, the international nature of the enterprise, and the wide interest that it evoked, well beyond the scientific world. With the international story, I have tried to show that the co-operation that took place with regard to promoting expeditions and collating results was probably less significant than the national rivalries, the dangers of travelling during the war, and the selection of locations for observing that related directly to imperial and trading interests.

There are so many fascinating stories to which we cannot do justice in the available space. I am hoping to include one of the best – the sad tale of Guillaume Le Gentil – but it is impossible to explore the background fully. This includes the Seven Years’ War and, specifically, the French/British rivalry in the Indian Ocean and desire for access to India and trade routes. This military and geopolitical history does not always get enough attention in the story of longitude. Not only did overseas trade and competition provide a spur to finding a solution, the process of finding one was sometimes impeded by war (for example, when Harrison’s first timekeeper was to be tested, they were unable initially to make the journey to the West Indies required by the 1714 Act), and sometimes , of course, contributed to the extension of imperial interests – as in the voyages of Cook and those who followed.

Because the history of transit observations is wound up with that of Cook (his first voyage was a transit expedition, as well as a testing ground for the new Nautical Almanac and a mission to locate and claim the southern continent), the current interest surrounding the 2012 transit has encouraged some to think about longitude and navigation. I spotted, on The Transit of Venus site blog, a post by Nick Lomb on How Cook navigated to Tahiti. This includes a discussion of the extent to which Cook knew “his position at all times” as a result of having access to the first edition of the Nautical Almanac. This mainly focuses on the point that lunar distances won’t work in cloudy skies, but misses the fact that Cook and Charles Green (the official astronomer, and former ROG assistant) ran out of Nautical Almanac predictions over the course of the voyage and that the length of time it took to calculate position by lunar distance usually meant that the navigator would only know where he had been rather than where he currently was. Precise position for charting and, especially, for locating observers of the transit of Venus would have been carried out by observing transits of Jupiter’s satellites rather than, or as well as, lunar distances.

Readers of this blog might also be interested in the current voyage of the replica of Cook’s ship, HMB Endeavour, owned by the Australian National Maritime Museum. The crew is currently cirumnavigating Australia and will stop at Lord Howe Island (named after Richard Howe, a regular attendee of Board of Longitude meetings in the 1760s, as Treasurer of the Navy, and in the 1780s, as First Lord of the Admiralty) to observe the transit of Venus. Those on board, either for the whole circumnavigation or for the transit of Venus leg, will be learning and using 18th-century sailing and navigation techniques. I am assuming that they have 21st-century backup!

Katy’s recent blog on clocks in novels reminded me of Laurence Sterne’s The Life and Opinions of Tristram Shandy, Gentleman, published in several parts between 1759 and 1767. Sterne’s novel also appeared in a recent Guardian list of clocks in books, which succinctly explains the timekeeper’s role in nearly preventing Tristram’s conception.

Referring to Tristram Shandy gives me an excuse to mention a couple of other quotes from this extraordinary work, which manages to refer to a bewildering array of topics, longitude included.

What’s interesting is that the novel’s publication dates span the various developments leading to the 1765 Longitude Act, which arose from the (largely) successful testing of two methods for finding longitude at sea – lunar distances and Harrison’s timekeeper (H4). Sterne’s brief references seem, however, to stem from an earlier period when the quest for longitude was considered one of the great imponderables.

In the first, Tristram’s uncle is in a quandary in his attempts to offer sympathy:

Before an affliction is digested – consolation ever comes too soon; – after it is digested – it comes too late: so that you see, madam, there is but a mark between these two, as fine almost as a a hair, for a comforter to take aim at: my uncle Toby was always either on this side, or on that of it, and would often say, he believed in his heart he could as soon hit the longitude…

The second is from Parson Yorick and needs little in the way of comment:

I think the procreation of children as beneficial to the world… as the finding out the longitude.

It’s easy to assume (or so I’d always assumed) that the adoption of new technologies is largely down to some assessment of the inherent qualities of the proposed innovations, so I always find it intriguing to come across instances where other factors are at work. I came across one example in writing a paper I gave about Tobias Mayer a few months ago.

It centres around the trials and adaptation of a circular instrument (a repeating circle) designed by Mayer and of which he sent a wooden model to London in 1755. The circularity of the instrument was crucial to Mayer’s claims that it could be used for accurate observations of lunar distances at sea, since by making repeated observations around the circle and then averaging them, you are taking advantage of the fact that a circle is always 360 degrees, so that even if you haven’t divided its scale evenly the differences cancel out. The circle by its nature guarantees the instrument’s accuracy.

But this principle was abandoned when the prototype came to Britain, where a brass version was made by one of London’s most trusted instrument makers, John Bird. Sea trials by Captain John Campbell showed the new instrument to be cumbersome, however, with only a third of the scale usable. The solution, James Bradley, the Astronomer Royal, later wrote, was that,

as the principal use of this [circular] construction is to obviate the inconvenience proceeding from the inaccurate division of instruments and as that might be sufficiently removed by the care and exactness with which Mr. Bird is known to execute those that he undertakes to make; a sextant of a radius, twice as long as that of the circular instrument, was made by him, and afterwards used by Capt. Campbell in taking several observations on board the Royal George in different cruises near Ushant in 1758 and 1759

This translation from circle to sextant meant discarding the mathematical certainty of the circle for the contingent guarantee of accuracy provided by the craftsmanship of one man, John Bird. To Bradley, Bird was so good that his name on the instrument was guarantee enough.

In later years Bird received a reward from the Board of Longitude for publishing an account of his method of dividing arcs by hand. Valuable hands indeed.

Images

Portrait of John Bird (National Maritime Museum, Greenwich, neg. PW3435)

Bird’s signature on an early marine sextant, c.1758 (National Maritime Museum, Greenwich, museum no. NAV1177)

To put your minds at rest, I have been attempting to do a bit of research on this trip too. This has included going to archives in Göttingen and Hannover to look at letters relating to the years of lobbying and negotiation – between Göttingen and London - that had to happen before Tobias Mayer, or rather his widow, was finally awarded £3,000 for his contribution towards making the lunar distance method possible at sea.

Funnily enough, most of the stuff I looked at was in German and pretty indecipherable (to me) due to the handwriting and my own lack of German skills, although I did come across some letters in English, French and Latin as well. I’ve ordered lots of copies, so we’ll have plenty to work on, but a couple of things caught my attention immediately.

One thing I’m still trying to piece together a bit more, for instance, is Christopher Irwin’s marine chair, and I’m pretty sure I saw it described in one letter as ‘Erwin’s Easy Chair’, which makes it sound even more marvelous. I hope I’m not disappointed when I look at the copy again.

Another letter (in French) was from Mayer’s widow, Marie Victoire, to Lord Grenville. It’s an attempt to persuade Grenville to help her get the reward her late husband’s work merited. The bit that caught my attention was a passage that seems to claim that a repeating circle of Mayer’s design was used for longitude determinations by lunar distance on a voyage to ‘Arabia’ begun in 1761 by Carsten Niebuhr. It is well known that Niebuhr carried out lunar distances, but the other evidence suggests that this was with an octant. It may well be that she was wrong about the instrument used. It is more likely, for instance, that she was thinking of the ‘astrolabium’, a circular surveying instrument based on Mayer’s repeating principle, with which Niebuhr made a few measurements (which was something Ivan Tafteberg Jakobsen talked about at the conference in Kassel). In any case, it’s got me wanting to check things out a bit more.

More on Nevil Maskelyne, I’m afraid. Because I was doing another talk recently, I was looking again at one of the images we have of him, which was among some manuscripts that came to the Museum a couple of years ago.

The image appears to be for a medallion commemorating Maskelyne, although I’m not aware of one being produced. I’d love to hear of any that are known. Anyway, the moon appearing in the background seems fairly straightforward, given Maskelyne’s role in proving and promoting the lunar distance method, but I wasn’t so sure about the inscription – ‘MARE PRÆSTAT EUNTI’.

After some hunting (well, Google searches), I decided that it appears to be from Ovid’s Heroides (The Heroines), no. 15, Sapho to Phaon. This has the line, ‘Venus, orta mari, mare praestat eunti.’

The next problem was to come up with a good (or at least effective) translation. That’s one of the things I hate about Latin – too many possible meanings.

Looking at some previous attempts, I found Alexander Pope‘s version of 1717, which was reprinted into the 19th century, and runs, ‘Venus for thee shall smooth her native main’. A more modern translation by Florence Verducci in 1985 offers, ‘Venus, born from the sea, smoothes the waves for a lover’.

So I’d say the three words of the inscription could translate as something like ‘he smoothes the waves for them’, or ‘he smoothes the oceans’, again referring to Maskelyne’s navigational work. Given that it’s Latin, I’d be prepared to push it a bit further and exploit the ambiguity as to whether Maskelyne or the moon is the subject and say, ‘they guide them [i.e. sailors] across the oceans’. But if anyone’s got any better ideas, I’d love to hear some suggestions.

Incidentally, I also found Horace Walpole using the whole line in a letter to Mary Berry in 1796:

I rejoice at your bathing promising so well. If the beautiful fugitive from Brighthelmstone dips too, the waves will be still more salutary;–