About the question how a person can be used as gnomon in a sundial. One solution is the already mentioned analemmatic sundial. The hourpoints lay on an ellips and in the middle there is a scale for the date. A person places himself on the correct date of that scale and his shadow is pointing to the correct hour (of suntime).
Also a discussion was held about a sundial with a person of a certain length. This idea isn't so bad. In Germany I once saw a dial with a scale for persons of different lenghts. They have to stand on a mark of their length and then their head (or the top of their head) is just on the place of a normal style, parallel to the earthaxis. But the style itself isn't there. It is just a matter of easy mathematics to make such a scale. The dial itself then is an 'ordinary' horizontal dial and it will work correct all over the year (in suntime). The reading is done at the point where the shadow of the persons head falls. A correction for longitude can be build in, but not the correction for the equation of time. Fer J. de Vries.
