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.’
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.
 John Harrison, Remarks on a Pamphlet lately published by the Rev. Mr Maskelyne, under the Authority of the Board of Longitude (London, 1767), pp.22-3