As many of you will know, Alex Moulton shared his birthday with one of the greatest Victorian engineers, Isambard Kingdom Brunel. There is also a more direct link in that Brunel was a customer of Stephen Moulton, Alex Moulton’s great-grandfather. Stephen Moulton had, of course, founded the Moulton Rubber Co. in Bradford on Avon in 1848. Aside from the rubber requirements of the Great Western Railway, when Brunel was specifying the resilient rubber mast mounts for the Great Eastern steamship he wrote directly to Stephen Moulton at The Hall. He noted in his diary that “I know of none other than Moulton of Bradford on Avon, Wiltshire, who can make the right sort of material.”

Brunel’s great Box Tunnel - the longest in the world at the time - was completed in 1841. Just one year later the Devizes Gazette reported on the rumour that on April 9th - Brunel’s birthday - the sun could be seen shining directly through the nearly two-mile length of the tunnel. This hypothesis was never directly tested but many thought that Brunel had put his engineering and mathematical skill, and his mischievous sense of humour, to good use.  The Box Tunnel was believed to be aligned with the stars in the manner of the Pyramids, Stonehenge and Newgrange.

One Wednesday afternoon working with Alex Moulton led to a discussion about the Box Tunnel and the rising of the sun on April 9th.  The suggestion was made that perhaps if a visit to prove (or disprove) this possibility could be arranged, it would be a terrific and fascinating adventure.  I forget the year of this conversation, but deduction would indicate that it was in 2009.  The response to my enquiry from Network Rail was predictably negative, and I was left with the feeling that even Isambard himself would have had no luck with a similar request.

It was not until 2017 that Great Western Railway and Network Rail engineers had the opportunity to observe what really happens in the Box Tunnel on April 9th.  With the line closed for electrification and engineers in total occupation of the track bed, the GWR finally had their chance.  The sun rose and revealed that the tunnel does indeed almost magically align with the rising sun, although not perfectly enough to shine all the way through to the western portal.  So one mystery of the Box Tunnel is at least partly solved, whilst the underground areas to the north and the south of the tunnel remain shrouded in secrecy.

Happy Birthday, Alexander Eric Moulton and Isambard Kingdom Brunel.  We raise a toast to the great engineers who make the modern world what it is.

Click here to read more about Alex Moulton’s birthday.