Dear John, You are not wandering too far off topic...
> I used to train architectural students to > pace a metre accurately. When I take a party on a local Sundial Walk I always start off by congratulating them on each bringing along their own sundials. I ignore their blank looks and explain that every individual is a self-contained altitude dial. By pacing out the length of your own shadow you can determine the time. I then pick someone who looks psychologically robust and stand him with his back to the sun. I point to the shadow of the top of his head and ask him to see how many steps it takes to walk that far. The whole party instantly sees the problem. It is not only rainbows that are difficult to get hold of :-) I expect this practice counts as treating an individual as an experimental subject and I should ask for written consent and evidence that it is "informed consent". No doubt shadows have rights too especially if they are human! All the best Frank --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
