Digging wells

Back in August 2008 I published a photo of a deep well in France and asked how on earth it could have been dug. The best suggestions I have had were from Scott George in the USA.

On the subject of drystone well construction, when I was much younger, a friend of my grandfather told me they used to dig down a couple of feet and place a large metal ring at the bottom of the hole. They would then lay up there stone to the surface and then dig under the ring to slowly lower it and then add more stone to the top. He said the kept doing this deeper and deeper. I have no idea if this is possible or accurate. Either way, it sounds dangerous. I also have heard that they would excavate the hole, so that the holes depth and width at the top were the same. So a hole 10 feet deep would have a width of 10 feet at the top in the shape of an inverted cone. They would then lay up the well wall and backfill as they went along. This sounds more plausible to me, but that is a tremendous amount of earth being excavated. Where I live many of the wells are around 10 to 20 feet deep and the walls are mortared. I don't think I have ever seen a drylaid well around here. Scott