Chronometers, charts, charisma: on histories of longitude

Charismatic megafauna are exotically impressive creatures guaranteed to attract immediate public fascination and sympathy. Their images and life stories provide indispensable resources for keen environmental campaign groups and publicists. The expression itself – charismatic megafauna – is barely a few decades old. Part of its point is to recall and contrast the hosts of apparently less alluring beings at least as crucial and fragile, possessed of their own cultures and needs, but who instead somehow have to rely for survival and support on the easier appeal of these larger and more compelling beasts. It is tempting to apply the term to less animate, but no less strangely charismatic, articles. In a host of salvage operations and museum collections, objects such as dinosaurs, Pharaonic mummies, totem poles and railway engines all play such roles. The charismatic megafauna of the National Maritime Museum include John Harrison’s astonishing 18th-century sea clocks, now widely reckoned the most important timekeepers ever constructed, not least because of their role in the determination of maritime longitude. Like so many of the artefacts currently held as part of the nation’s heritage, their highly troubled careers embody a remarkable range of themes in craftsmanship and science, conservation and administration, repute and controversy.