Being Distracted in Paris

It’s not so long ago that I wrote about the lack of opportunity one typically has at conferences to appreciate the interesting places one gets to visit. As a counter to that slightly depressed commentary, I should add that I have specifically had some brilliant trips to Paris over the years, associated with work (as well as other trips such as my honeymoon!) although not, in most cases, actual conferences. Paris is in my view an amazing city; a good size to be able to walk all around – unlike London or New York – and I have always felt very safe there, although I’m sure there are bits that it might be less wise to visit. For the last few years – aside from a couple of wonderful trips courtesy of L’Oreal – ESPCI (which is one of the Grandes Ecoles in Paris) has been the excuse for an annual autumnal visit, as I serve on their International Steering Committee (ISC).  Previously, in the wake of my last 2 trips to ESPCI, I have talked about the situation for women in France and the rather special education that students receive at ESPCI, but this time I’d like to remark on the cultural side of my trip.

Each year, ESPCI not only works the ISC hard, but also ensures we get a bit of ‘play’ and some excellent meals in famous restaurants and even, one year, on a rather damp Bateau Mouche. These events tend to start late in the day after a hard day’s work and run long into the night, at least by my standards. It makes for lengthy and tiring if rewarding days. In previous years the ‘play’ component has consisted of trips to a couple of museums and a concert. This year we were treated to a guided tour of the Paris Observatory, where we were shown around personally by James Lequeux, described as ‘astronome émérite à l’Observatoire de Paris’ on the web (who also happens to be the father of the ESPCI’s Scientific Director François Lequeux and, for any neutron scatterers amongst my readers, the brother-in-law of Henri Benoit).

We got to clamber around on the roof – with fine views of the Eiffel Tower, the Pantheon and other notable churches extending as far as Sacré-Coeur on the distant horizon – and look at the impressively large Brunner refractor telescope housed in its purpose-built dome. The building itself predates the Greenwich Observatory by several years: the Paris Observatory was built in 1667-72 and is the oldest observatory in the world, built during the reign of the Sun King Louis XIV. Greenwich was not founded until 1675. It is an impressive structure with a wide range of interesting objects on display. Many of these are, as one would expect, directly relevant to the development of observational astronomy, but some also relate to terrestrial surveying. Triangulation neatly explained by triangles, for instance, in some early mapping studies, and a coloured map of France based on Cassini III’s measurements (1756) is also on display. In this context it should be noted that four successive generations of the Cassini family acted as the first four Directors of the Observatory: Cassini I (Giovanni Domenico) 1671-1712, Cassini II (Jacques) 1712-56 , Cassini III (de Thury) 1756-84 and Cassini IV (Compte de Cassini) 1784-93. These dates refer to the periods when they were Directors, not their lifetimes.


1810 sculpture of Cassini I (Jean Dominique Cassini) prominently displayed at the Paris Observatory.

Not having made a study of the history of astronomy, my knowledge was sketchy and, as I discovered, very Anglo-centric. It’s always good to be reminded that England, or in this case Greenwich, is not necessarily the centre of the universe: the French have their own meridian, a brass line reaching across the ‘Meridian Chamber’, whose position was first established in 1667 as the observatory was set up. And outside the north-facing window is a fine straight road continuing the line of the meridian for a fair distance. When I asked one of the other (French) members of the party about the meridian, he instantly got out his iPhone to check the web for more information and came back with the fact that the English and French worked out a compromise about the meridian to the effect that the English could ‘have’ zero longitude but would have to convert to meters. If true, I think devilish British cunning came into play here, as miles are still alive and well in much of our countryside, but I haven’t found this story myself so maybe I was being wound up. In fact it wasn’t till 1884 that the zero meridian was finally determined to be situated at Greenwich, after an international conference (largely swung, as far as I can find out, by the Americans who had already adopted the British rather than French meridian).

Most of the objects on display were down to one or other of the Cassini’s, with Cassini I’s map of the moon’s surface (including a non-existent heart-shaped feature and a moon maiden: these, we were told, may have been in tribute to his wife), many instruments and the later Cassinis’ work on surveying all on display. But the object which most took my fancy was a copy of Newton’s Principia given to him by Edmond Halley, and with a dedication from Halley to Cassini I (you can see this in Figure 1 here but we got to see the pages open in a display cabinet). What we were told by Lequeux was that this book was presented by Halley to Cassini I in gratitude for Cassini having given Halley the idea that comets might return, shortly before the comet that bears his name was discovered. When I tweeted this fact the next morning, historians of science were less convinced that what I was told was true, with a swift response coming that the idea was actually due to John Flamsteed, the first Astronomer Royal who was based at Greenwich; subsequently there was a hint of a retraction of this point of view.

I can’t comment further on this, as a quick search on the web does not substantiate the anecdote. What is well known is that Principia was not a book that made much of an inroad into French thinking until well into the 18th century, when it was translated into French by Emilie du Chatelet, who was Voltaire’s mistress and invited Voltaire to come and live with her and her husband in an aristocratic ménage-a-trois. She is one of those rather invisible women of science from the past who – like Mary Somerville  and Ada Lovelace – really came into her own when getting her teeth into a job of translation. Then she could take the original work and weave in more ideas of her own, as described in Patricia Fara’s book Pandora’s Breeches.

The presence of the Principia, and other notes on display nearby associated with the Dutch scientist Christiaan Hugyens, served to remind me just how international science was back during the 17th and 18th centuries, something at least briefly impeded later by the French Revolution and its aftermath but not as much deterred as one might have expected by the relative difficulties of travelling at the time. Young gentlemen like Halley were expected to go on a ‘Grand Tour’, and if he happened to drop in on the Paris Observatory, perhaps stay there for some weeks or months, that was regarded as absolutely fine. Hugyens, meanwhile, was an early FRS despite being based in Paris and The Hague and mainly simply in correspondence with Londoners like Hooke and Newton.

So, for once, my work-based trip gave me an opportunity to get to grips with some history of science, as well as fulfilling my main role for ESPCI. I got to see some fascinating objects, and learned how uncritical my thinking had been about Greenwich’s central role in our astronomical and nautical past. However, I appreciate by writing this as such a novice in the topics I touch upon, despite having tried to check my facts I am laying myself open to correction on many fronts from the historical perspective. Please take it simply as a homage to some amazing bygone scientists.

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4 Responses to Being Distracted in Paris

  1. beckyfh says:

    A couple of things to clarify on meridians. There were, of course, many meridians, not just Greenwich and Paris, marking ports or capitals as well as those determined by the positions of astronomical instruments. The Paris one was used in France and particularly the important series of surveys associated with the Observatory. The Greenwich one became significant as a result of the publication of the Greenwich Observations and the Nautical Almanac from 1760s onward and, via that, its use in British Admiralty surveys and maritime charts. The wide use of these publications meant that, for example, Holland began using the Greenwich meridian as a prime meridian in the 1830s.

    It was reckoned at the 1884 International Meridian Conference that some 72% of the world’s shipping in tonnage used the Greenwich meridian already. France protested most, because they were the most committed to a different reference point. The conference did recommend that Britain should join the Metric Convention of 1875, as a sort of quid pro quo, and it’s something that the majority of British scientists would have been more than happy to do. However, the Conference delegates could only recommend this action, and the choice of Greenwich as prime meridian, to their governments. The only government that took action on ANY of the recommendations as a direct result of the conference was Japan.

    Rather, the move to an international meridian was relatively slow, as individual nations opted to codify practice, or simplify communications through adopting time zones and the Greenwich meridian on maps. France, notably, held out until 1911, and even then initially adopted it as “Paris Time, retarded by 9 minutes and 21 seconds”.

    As for Halley and Cassini, I note from this lecture by Simon Schaffer that Halley was in Paris in early 1681, working closely with Cassini, “then much concerned with the great comet of 1680-1681 that Halley himself had first seen on the road to the French capital… Halley obtained from Cassini his crucial book on the comet, later of importance in Newton’s calculations”. Apparently Cassini was wrong in his estimate of the period of the comet, but it is clear that they (as well as Flamsteed) discussed cometary orbits. The dedication was presumably written in 1687, well in advance of the prediction of Halley’s Comet, in 1705.

    Sorry for the length of the comment!

  2. Steve Eichhorn says:

    Only a comment to say thankyou for a very interesting post. Jules Verne’s 20,000 Leagues Under the Sea was written before the meridian situation was resolved and so contains a number of references to measures that poke fun at the arguments that were ensuing – note the use of “Greenwich meridian” and metres!

    “A fortnight later, two thousand leagues from there, the Helvetia of the French Line and the Shannon of the Royal Mail,4 sailing on opposite tacks the Atlantic between the United States and Europe, signalled a sighting of the monster to each other at 42° 15′ N and 60° 35′ W of the Greenwich meridian. From these simultaneous observations, it was claimed that the mammal could reliably be estimated to be least 350 British feet long, since the Shannon and the Helvetia were both smaller than it, although measuring 100 m from stem to stern. Now the biggest whales, the kulammak and the umgullick frequenting the waters around the Aleutian Islands, have never exceeded 56 metres—or indeed possibly ever reached that length.

    These reports arriving hot on the heels of one other, fresh observations made on board the transatlantic liner Pereire, a collision between the monster and the Etna of the Inman line, an official memorandum drawn up by the officers of the French frigate Normandie, a very serious declaration obtained from Commodore Fitzjames’s senior staff on board the Lord Clyde—all this greatly thrilled public opinion. In the countries of a lighthearted mentality the phenomenon was joked about; in the serious, practical countries of Britain, America, and Germany, it was a matter for serious concern.”

  3. ac maggs says:

    Clicking back to your earlier remarks on access:

    The preparatory system has classes in most medium sized towns- there is no need for
    a student far from Paris to go there for the two years. Many of these schools are state boarding schools. The rooms are not always very comfortable but a good student
    from a tiny village can usually get a place no more than a couple of hours from home, and will
    normally be back with the family for weekends.

    That said, the final result is often a selection of middle class (but state educated) students

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