Dear Jackie, You are right...
> I seem to remember hearing about a "sun well" > ... The sun only shone right down it at midday > when it was directly overhead. I once made a hunt-the-sub-solar-point trip to Hong Kong. I had been invited to give a course of lectures but I insisted on visiting at a time of year when the solar declination suited my ulterior motive! I also visited a friend who was chief engineer on a site where a massive pumping station was being built in a deep-water reservoir. At this stage the structure consisted of six huge vertical tubes, perhaps 3m in diameter and standing 40m high. When you looked down a tube you could normally see nothing beyond the top few metres. This site was five miles north of where I wanted to be but the sun's altitude would still be about 89 deg. 55'. While I was hunting the true sub-solar point my friend called the entire work-force together and told them all to look down these tubes. Spot on cue, the sun shone down the tubes and for a minute or so there was a blinding reflection from the pools of water at the bottoms of the tubes. Fast forward 10 years and I met another structural engineer at a wedding reception and he told me that he had worked on a number of projects in Hong Kong. It then turned out he had worked on this pumping station. One incident he remembered clearly... One day when it was fearfully hot, the chief engineer called everyone on site together and told us all that he had a mad friend who had calculated when the sun would shine directly down the tubes. We all had to lean over and look down and, sure enough, the holes suddenly went from deeply gloomy to blindingly bright. Hmmm. You never know where an understanding of the ways of the sun might lead you! All the best Frank --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
