Hello! An interesting use for an analemmatic sundial which I have only recently read about involves measuring how many hours the sun potentially shines on a given vertical wall. First you draw the analemmatic sundial on paper according to your geographic location. Then you place a ruler on the particular spot of the date line you are interested in. Then you rotate the ruler around that point by the measured declination of your wall. The ends of the ruler give you the first and last hours of wall illumination, provided the sun is still over the horizon (sunrise and sunset times have to be considered).
Also, if you stretch your arms 180 degrees apart pointing one arm to the sunrise/sunset time for that particular date, the other arm will show you the direction of sunrise/sunset. These are from Heinz Schumacher's book "Sonnenuhren vol. 1". Regards, Dan Uza
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