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Light Through Box Tunnel
Alan Payne May 2017 Most villagers have heard the claim that light can be seen through the tunnel at dawn on Brunel's birthday (9 April). This is far from a recent claim because it was first mentioned in April 1842 with a report that Box Tunnel presented a most splendid appearance ... on Saturday last (16 April) caused by the shining of the sun directly through it and giving the walls a brilliancy ... as though the whole tunnel had been gilt.[1] This story was repeated in May 1842 when passengers could see that the light at the other end was very perceptible.[2] Since then the claim has been made by many authors without any evidence. But is the claim true or just a marketing tool for Box Tunnel and Brunel? Right: Frontispiece referrring to the light (unknown source) |
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Gathering Evidence
British Rail engineers made observations through the tunnel in 1988 and concluded that it was perfectly straight and that light comes through on 6 and 7 April.[3] A detailed, mathematical analysis of the gradient showed that it was not a deliberate construction by Brunel because the sun only shines through when its angle is absolutely in line, which would not have been the case in the years after it was constructed until 1843.[4]
Apart from this rare occasion, lighting inside the tunnel was a problem because of the disconcerting effect it had on passengers and the inability of drivers to see obstructions on the line. In March 1842 it was proposed to install a Bude Light (very bright oxygen lamp) but cost prevented this.[5]
Proof of the Theory?
Below is the photo taken on 6 April 1985 at sun rise through Box Tunnel. QED? It seems that light does come through about, but not on, Brunel's birthday and we should accept the words of Wikipedia: it has been asserted that it is impossible to guarantee the effect on a particular calendar day, because the angle at which the sun rises on a given date varies slightly with the cycle of leap years ?
British Rail engineers made observations through the tunnel in 1988 and concluded that it was perfectly straight and that light comes through on 6 and 7 April.[3] A detailed, mathematical analysis of the gradient showed that it was not a deliberate construction by Brunel because the sun only shines through when its angle is absolutely in line, which would not have been the case in the years after it was constructed until 1843.[4]
Apart from this rare occasion, lighting inside the tunnel was a problem because of the disconcerting effect it had on passengers and the inability of drivers to see obstructions on the line. In March 1842 it was proposed to install a Bude Light (very bright oxygen lamp) but cost prevented this.[5]
Proof of the Theory?
Below is the photo taken on 6 April 1985 at sun rise through Box Tunnel. QED? It seems that light does come through about, but not on, Brunel's birthday and we should accept the words of Wikipedia: it has been asserted that it is impossible to guarantee the effect on a particular calendar day, because the angle at which the sun rises on a given date varies slightly with the cycle of leap years ?
References
[1] The Bath Chronicle, 21 April 1842
[2] The Bath Chronicle, 5 May 1842
[3] Colin G Maggs, The GWR Swindon to Bath Line, p.77
[4] New Civil Engineer, 4 April 1985, p.29-31
[5] Colin G Maggs, The GWR Swindon to Bath Line, p.32
[1] The Bath Chronicle, 21 April 1842
[2] The Bath Chronicle, 5 May 1842
[3] Colin G Maggs, The GWR Swindon to Bath Line, p.77
[4] New Civil Engineer, 4 April 1985, p.29-31
[5] Colin G Maggs, The GWR Swindon to Bath Line, p.32