Brunel’s birthday gift

05 April 2017


05 April 2017


Discover all about how Brunel may or may not have left himself a present hidden in the construction of one of his greatest projects.

I can’t remember ever buying myself a birthday gift. It’s not something that I’m against particularly, but I do find the idea a little odd. Not so for Isambard Kingdom Brunel, who may have left himself a present hidden in the construction of one of his greatest projects.

While conducting some research last week I went into the Brunel Institute and took a look at one of Brunel’s beautiful sketchbooks (acc no. DM162/8/1/3/GWR Sketchbook 11/folio 42, if you’re interested). While looking for details of his design of the Great Western Railway I came across his sketches for the infamous tunnel at Box. A controversial project, called ‘monstrous and extraordinary, most dangerous and impracticable’, Box Tunnel claimed an estimated one hundred lives in its construction. Yet it’s also the site of a great Brunel legend.

Allegedly the tunnel, which is almost two miles long, was constructed at the exact angle to allow the sun to align itself perfectly. This meant that light could shine down the entire tunnel and be seen from one end to the other. One historian has likened this to a giant gun barrel pointing at the sun. This phenomenon is said to occur only on one day a year: 9 April, Brunel’s birthday.

Could it be a present to himself? Most Brunel enthusiasts have refuted that this event occurs (it’s all about atmospheric refraction but between you and me, I had to take their word for it).  If you were to pitch up outside the tunnel on 9 April this year I’m afraid you would almost definitely be disappointed. So where did the myth come from?

A little digging showed that the very first recording of this event is from 16 April 1842, in the Devises Gazette.

“On Saturday the Box Tunnel presented a most splendid though singular appearance, caused by the shining of the sun directly through it, and giving the walls a brilliancy, to use the expression of an eye witness, “as though the whole tunnel had been gilt.”

So, the event did occur at least once in the year after the Box Tunnel opened, at least according to a local newspaper. A quick search online showed that 9 April fell on Saturday that year and it has also been suggested that Brunel made a change of travel plans on his birthday which would put him near Box at roughly the right time – perhaps to view his birthday gift? After checking Brunel’s diaries, I sadly found no comments from the great engineer.

It’s a hard myth to bust or to confirm, but it’s certainly nice to imagine Brunel standing at the west end of the tunnel on his birthday, bathed in sunlight and satisfaction for just a moment – even if it only occurred for one year.

More recently theories have suggested that the illumination occurs three out of every four leap years on 6 April, which coincides with the birthday of Brunel’s sister; Emma Joan. I’m yet to be convinced – it all seems a little desperate – but maybe an expert in ‘atmospheric refraction’ can shine a light (sorry!) on the subject… so long as they speak slowly.

And with that, I suppose all that remains to be said is:

Happy Birthday Brunel!

Updated 5 June 2017: Since writing this I’ve managed to debunk the theory that Brunel changed his plans to head past the tunnel. It was suggested that he travelled past Box on his way to Sardinia to advise the king there. However his friend wrote a very detailed account of himself and Brunel travelling from London, and makes no mention of Box at all.

Author: Luke Holmes, Interpretation Officer

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