Years later, I now have the knowledge and the tools to do the calculations and see if it might be true. It isn’t; but there remain some fascinating questions. The sun does shine through the tunnel, but a few days earlier than Isambard’s birthday. Furthermore, if atmospheric refraction is ignored – this is the lensing effect of the atmosphere close to the horizon – the rising sun really does shine through the tunnel on the day in question.
I wanted to know when the story first came to light, as it were, and also what was the provenance of a Victorian lithograph reproduced by Beckett. It shows a train exciting the tunnel and has the legend:
It is a remarkable fact that annually on the morning of April 9th, the sun’s rays penetrate through the Great Box Tunnel of the Great Western Railway and on no other day in the year; The Daily Telegraph, April 12th 1859. Even more remarkable is the fact that April 9th is the birthday of Brunel.
Even more remarkable still, the Daily Telegraph of April 12th 1859 makes no mention of the Box Tunnel whatsoever… This last fact has troubled me for years, but the new newsroom at the British Library has the latest microfilm viewers installed, and using one of these I was able to establish this week that the story was run in the Daily Telegraph, not on 12th April, but the previous day.
Scrutiny of other newspapers of the period indicates that the legend was repeated many times between 1842, the year after the tunnel was finished, and 1859, the year Brunel died, but with the exception of the above mentioned lithograph, no mention was made that April 9th was Brunel’s birthday. Was it a conspiracy of silence to protect the reputation of the great man? I need to track down that lithograph and find out when it was published. Aggravatingly, Beckett does not record its provenance, and an enquiry to his publisher received no answer.