RMweb Gold Metr0Land Posted December 11, 2017 RMweb Gold Share Posted December 11, 2017 I grew up believing that the sun shone directly through Box tunnel at dawn on Brunel's birthday which I'm sure even the MiM know is 9th April. At some stage I recall hearing it was an urban myth and so decided to use one of the online tools like Suncalc. For 2018 it looks to me like it shines directly through at dawn on 04April so it looks to me to be substantially but not 100pct true? Has anyone else checked this? Link to post Share on other sites More sharing options...
St. Simon Posted December 11, 2017 Share Posted December 11, 2017 I grew up believing that the sun shone directly through Box tunnel at dawn on Brunel's birthday which I'm sure even the MiM know is 9th April. At some stage I recall hearing it was an urban myth and so decided to use one of the online tools like Suncalc. For 2018 it looks to me like it shines directly through at dawn on 04April so it looks to me to be substantially but not 100pct true? Has anyone else checked this? Network Rail did a check, and took a photo, during the blockade of the tunnel a couple of years ago, but I'm not sure whether it was actually Brunels birthday. Simon Link to post Share on other sites More sharing options...
mike hughes Posted December 11, 2017 Share Posted December 11, 2017 Wasn't there something on TV about this? Sorry can't remember which programme Michael Link to post Share on other sites More sharing options...
RMweb Gold teaky Posted December 12, 2017 RMweb Gold Share Posted December 12, 2017 Fred Dibnah mentioned it in his book so it may also have featured in his "Age of Steam" TV series. Link to post Share on other sites More sharing options...
RMweb Gold stovepipe Posted December 12, 2017 RMweb Gold Share Posted December 12, 2017 Wasn't there something on TV about this? Sorry can't remember which programme Michael I think I saw this. The conclusion was on the lines of it can happen but usually not, something to do with a slight wobble in the tilt of the earth? Link to post Share on other sites More sharing options...
Guy Rixon Posted December 12, 2017 Share Posted December 12, 2017 The Earth's axis has two significant motions. Precession makes the axis move slowly in a circle on the sky. The radius of the circle is the Earth's axial tilt, ~23 degrees and the axis goes once round the precessional circle in about 26,000 years. Nutation adds a smaller wobble on the precessional path with a period of 18.6 years. Without working out the numbers, I would guess that the precessional shift over a couple of hundred years is negligible, but the nutation changes the day of alignment at Box. Link to post Share on other sites More sharing options...
APOLLO Posted December 12, 2017 Share Posted December 12, 2017 And I always thought the universe revolved around Swindon, centre of God's Wonderful Railway !!! Brit15 1 Link to post Share on other sites More sharing options...
JimC Posted December 12, 2017 Share Posted December 12, 2017 (edited) The conclusion this year, when they looked, was that it doesn't, although you have to read hard to find it and ignore the headline! e.g. https://www.theguardian.com/technology/2017/apr/10/isambard-kingdom-brunel-birthday-box-tunnel-bath-sun To repeat what I said elsewhere on the forum, its worth noting that if you have a straight tunnel on a gradient so that it points above the horizon, and its aimed vaguely south of east or vaguely south of west, then its very unlikely that the sun won't shine straight through on one day or another. The sun crosses an awful lot of sky in the course of a year! Edited December 12, 2017 by JimC 1 Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted December 12, 2017 RMweb Gold Share Posted December 12, 2017 There are a lot of variables to take into account when making an observation of this sort, and not actually seeing the tiny dot of light that would be visible from the western portal does not mean that there is no alignment allowing it on Brunel's birthday; it is known to be pretty close! The air in this very long tunnel would have to be completely clear of fumes, mist, or atmospheric pollution, and the pin prick of light would be tiny. I was once on the first (05.20 IIRC) Cardiff-Bristol dmu in the 70s, sitting in the cab with the driver partaking of a can of tea, when, following a weekend possession in Severn Tunnel which we were the first up train through after, and just having begun the climb from the bottom, he pointed out a very small dot of light ahead and said it was the English portal, and that in 20 odd year on the job he'd never seen it before. I had my doubts, but it very slowly got bigger and eventually became large enough to let the train out of the tunnel; he was right! This was not a direct sunrise alignment, but a very bright eastern morning sky. Seen from the bottom, the tiny dot of light was very hard to see from 2 and half miles away, a similar distance to Box, and I probably would not have noticed it until the last mile or so. Brunel's father Marc was known to be fascinated by the French discoveries that followed Napoleon's occupation of Egypt, and this sort of pyramid trickery sounds very much like the sort of stunt Ismbard might have attempted; I am inclined (at 1 in 100 in a dead straight line) to believe it! 2 Link to post Share on other sites More sharing options...
APOLLO Posted December 12, 2017 Share Posted December 12, 2017 Interesting subject - Found these on the web. https://www.pressreader.com/uk/rail-uk/20170426/282969629956981 https://www.theguardian.com/technology/2017/apr/10/isambard-kingdom-brunel-birthday-box-tunnel-bath-sun http://www.dailymail.co.uk/sciencetech/article-4397442/Brunel-s-Box-Tunnel-catches-sunlight-birthday.html http://www.adamscottimages.com/blog/ Seems the old current bun does shine through !!! Brit15 Link to post Share on other sites More sharing options...
NittenDormer Posted December 12, 2017 Share Posted December 12, 2017 I hope Brunel saw this as a metaphor. Link to post Share on other sites More sharing options...
Guy Rixon Posted December 12, 2017 Share Posted December 12, 2017 ... the pin prick of light would be tiny. The tunnel is 2350m long. Assuming that it's 10m wide, one portal subtends 0.24 degrees when seen from the other. That's half the angular diameter of the sun (or the full moon, which is the same size). It's not vast, but I wouldn't call it tiny. It follows that the image of the sun will fill the far portal if one looks through the tunnel at the right moment. Link to post Share on other sites More sharing options...
APOLLO Posted December 12, 2017 Share Posted December 12, 2017 Back in the 60's when we switched our telly off we would slowly watch the "end of the tunnel disappear" !!!!! Anyone remember the old 405 lines valve TV's ? Brit15 Link to post Share on other sites More sharing options...
RMweb Premium jjb1970 Posted December 12, 2017 RMweb Premium Share Posted December 12, 2017 And I always thought the universe revolved around Swindon, centre of God's Wonderful Railway !!! Brit15 GOD was asked to change his name as he was tarnishing the image of the GWR by his fraudulent attempt to be associated with them. 1 Link to post Share on other sites More sharing options...
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