Random thoughts / Weird and Wonderful

Numa Pompilius and the Mathematical Bridge

mathematical bridge

The Mathematical Bridge at Queens’ College

The famous wooden Mathematical Bridge at Queens’ College is a highlight of the Cam punt tour. It bridges the river to connect the two parts of Queens’. The story goes something like this:  “It was designed by Sir Isaac Newton  – and put together without any nails or bolts. When they had to take it down to repair it they couldn’t figure out how to put it back together again, and that’s why the bridge you see now is bolted together.”

Now, the Mathematical Bridge actually has nothing to do with Newton, and has certainly always been held together by more than just the gravity-defying Power of Maths (the original was built in 1749). But the story of a wooden bridge with no nails actually has a much longer pedigree.

Plutarch tells us in his Life of Numa (IX.3-4) that the first bridge ever built in Rome (known as the Pons Sublicius, or bridge of piles, presumably because of the way it was constructed) was also a wooden bridge, with no iron nails. “The Romans held the demolition of the wooden bridge to be not only unlawful, but actually sacrilegious. It is also said that it was built entirely without iron and fastened together with wooden pins in obedience to an oracle.” Whenever the bridge was destroyed by the Tiber flooding or other disasters (always a bad omen) it would be piously rebuilt in the same form.

The similarities between the two stories are pretty striking. Both try to explain the anomaly of a lone wooden bridge on a river bridged by stone – an antique curiosity in both cases. Just as the Mathematical Bridge legend links its creation to a sage of the past (Newton), the Pons Sublicius is connected with Rome’s farsighted second king, Numa Pompilius (or his grandson, Ancus Marcius). The continuity of form is emphasised – the Mathematical Bridge has also been substantially rebuilt twice but maintained the same design. Both are linked with supernatural knowledge – whether that’s oracular or mathematical!

Coincidence? A quick google has revealed the existence of other wooden bridges without nails, the Kintai Bridge in Japan, or example. Or is it possible that the Queens’ legend was originally influenced by scholars’ knowledge of the Pons Sublicius (which is the bridge destroyed in the famous story of Horatius Cocles)?

8 thoughts on “Numa Pompilius and the Mathematical Bridge

  1. Nice article, Hannah! The usual version of the story I’ve heard around Queens’ is that it wasn’t dismantled for repairs but by engineering/maths students (delete according to preference) eager to discover how it stayed up. Which I guess sort of parallels the idea that taking it apart is in some way unsanctioned. On supernatural connections, Newton was, of course, not just a mathematician but an alchemist obsessed with the occult, who wasn’t above a bit of oracular divination himself.

    The role of pedantry in all this is fun. As is repeatedly drummed into all Queens’ students along with the correct positioning of the apostrophe in the college name, it’s not really called the Mathematical Bridge: the correct name is the Wooden Bridge. Arguably the most interesting thing about it’s not the engineering at all, but how almost every aspect of it is elaborately mythologised and flagged with various degrees of falseness. The extent to which you can point out which bits are untrue, which bits are *really* untrue and which bits are completely bonkers becomes a shibboleth for dividing us (Queens’ students) from them (other Cambridge students) and *them* (punt tours). An interesting development since I first came to Cambridge is that punt tour guides have increasingly moved from straightforwardly telling the Newton story to saying ‘People say this; it’s not true’ and then telling it anyway. I’m not quite sure what my point was, but I guess it’s a nice example of how important folk-histories and social context are to the function and meaning of architecture and material culture more broadly.

    • Thanks! I’ve often thought a really interesting article could be written about the stories tour guides tell – because ultimately, in some ways, they have more impact and reach a much wider audience than anything more academic even if more true.

  2. My favourite version of the Mathematical Bridge story is the one in which Newton builds the bridge without nails, then several years later he discovers gravity and realises his bridge is physically impossible. So comes back and rebuilds it with nails himself.

    • I’ve never heard that one around Queens’. I’m really curious now to know how different versions of the story correlate with different colleges, departments and age-groups. My suspicion is that Queens’ versions would be quite conservative except when they respond to innovations by punt tour guides, whereas further away more innovation ought to be prevalent.

      • I think it was Rupert who told me that one, so for all I know he made it up himself. Surely somebody ought to have done a sort of folklore study of the dissemination of Cambridge myths…If not, maybe you ought to change your post-doc proposals!

  3. By the way, entirely off-topic, I just noticed that ‘Res Gerendae’ is an anagram of ‘Earn Degrees’. I wonder if that’s trying to tell us something. But then it’s also an anagram of ‘Renegade Seer’.

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