Vol 458|16 April 2009 BOOKS & ARTS A measure of importance Astronomer François Arago of the Observatory defied war, disease and death to survey the running through his city — and helped define the we use today, explains Andrew Robinson.

Full Meridian of Glory: Perilous Adventures drinking brandy”. And when Murdin includes Fortunately, Arago, clearly a hero to Murdin, in the Competition to Measure the Earth a full-page photograph of NASA’s notorious gets a lively chapter of his own. Arago became by Paul Murdin Mars Climate Orbiter — lost in space in 1999 director of the in 1843. In Springer: 2009. 187 pp. £15.99 as a result of a muddle between the imperial 1848, he was briefly the minister of war and of units used in its design and the metric units the navy, and even the head of state for 46 days used in its operation — the past and present during that Revolutionary year. He is known Astronomer Paul Murdin began his career in are seamlessly integrated. for applying the wave theory of light — pro- 1963 at the ’s Royal Greenwich The same cannot be said for the main text. posed by his friend Thomas Young — to stellar Observatory. Proud of his employer’s history, Murdin draws on an extensive and distin- aberration, and for suggesting the crucial test going back to the observatory’s foundation guished cast of scientists, including the four between wave and particle theory by comparing by King Charles II in 1675, Murdin became key figures of the Cassini dynasty and their the speed of light in water and air. But Arago’s curious about the running nemesis , whose theory on journey to survey the mountains of through Greenwich that, in 1884, came to during the war with in 1806–09, define Greenwich Mean Time. He learned, following the death of Méchain from however, that its roots lay not in Britain but malaria, was both significant science and in seventeenth- and eighteenth-century colourful adventure. Running the gauntlet France, intertwined with the French Revo- of isolation, bad weather, equipment fail- lution. The accurate scientific measurement ure, brigands, homicidal Spanish mobs and of the Paris meridian also formed the basis a British blockade of French ports, Arago of the nineteenth-century metric system and completed his measurement of the meridian its modern form, the Système International at Majorca in the Balearic Islands. At one (SI). Murdin’s book Full Meridian of Glory, point, he had the strange experience of read- DE PARIS C. STEUBEN/OBSERVATOIRE its title taken from Shakespeare’s Henry VIII, ing in a newspaper about his own execution is the outcome of his long fascination with by hanging, in which he had apparently met the Paris Observatory, founded by Louis death heroically. XIV in the late 1660s. Murdin’s interest is In an unusual final chapter, Arago returns reinforced by his regular professional visits as Murdin gives a guided walk through to the Paris headquarters of the European Paris following the trail of more than Space Agency. 100 bronze discs set into the pavement, Others have trodden this path before, which carry merely the inscription ‘ARAGO’ notably Ken Alder in his prizewinning The and the compass direction letters N and S. Measure of All Things (Little, Brown; 2002), a They mark the line of the Paris meridian. historian of science mentioned only once by The discs were created by a Dutch concep- Murdin. Although a better narrative writer tual artist, Jan Dibbets, winner of an open than Murdin, Alder focuses on the 1790s, competition to honour Arago on the bicen- whereas Murdin ably covers four centuries. tenary of his birth in 1986. “The idea was that Alder also lacks the enthusiasm and knowl- the people of Paris would accidentally come edge of a working scientist. François Arago was influential in both science and politics. across the medallions, wonder about them Murdin knows what it is like to make and thus discover Arago,” Murdin explains. night-time observations in sub-zero condi- was opposed by the elder Cassinis. The Cassini At the Louvre, three Arago medallions traverse tions. He would empathize with the French family reigned at the Paris Observatory for more the Denon Wing, and five others run across the savants who, in 1734–44, laboriously surveyed than a century, and mapped France through Cour Carrée behind the glass pyramid. In Dan and compared the length of a degree of their combined efforts. Also mentioned are Brown’s The Da Vinci Code, Murdin informs in polar Lapland with that in the equatorial the scientists who surveyed the Paris meridian us, the novel’s hero is drawn to the pyramid by Andes, to prove whether Earth was flattened at the turn of the nineteenth century — in par- the discs. Yet as this quirky book demonstrates, or elongated at the poles. “I can speak of the ticular, Jean-Baptiste-Joseph Delambre, Pierre the discs are not mysterious markers but a pain from personal experience, having left a Méchain and François Arago. Instead of weav- celebration of French science at its most ring of skin from around my right eye frozen ing them into the main text, Murdin mostly rational, symbolized by Arago. ■ to an eyepiece when I withdrew my head from discusses their lives in numerous thumbnail Andrew Robinson is a visiting fellow at Wolfson a telescope in an upstate New York observa- sketches set apart in paragraphs of small type. College, Cambridge CB3 9BB, UK. He is the tory,” Murdin writes. He recounts how French This typographical separation of the biographi- author of The Story of Measurement and The astronomer Pierre Charles Le Monnier “had cal from the scientific makes for an indigestible Last Man Who Knew Everything, a biography of a similar experience in Lapland when his and sometimes confusing read, even though the Thomas Young. tongue froze to a silver cup from which he was sketches are informative and often enjoyable. e-mail: [email protected]

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