By eyeballing the center of the shadow of the gnomon as it creeps across the time hashes cut through the equinox disk, one gets a fair indication of clock time. Sometimes it helps to hold a pointer, like a key or a pencil, in the middle of the shadow when orienting to the time tic five minute intervals and the direction they go. A pointer can help your eye balance both sides of the shadow and accurately clarify the middle. The eye can establish the center of a shadow as well as it can discern its slightly fuzzy edge. This is not digital.
Time read off this dial is within about seven minutes of clock time during the spring and summer, top of the disk, and can be different by up to 17 minutes in the fall and winter. The chart below tells the conversion to be added or subtracted. Take your time, and it will give you the time of your life and also confirm that your smart phone still has its charge.
Graph showing the 'Equation of Time'
This final addend brings longitude adjusted sun time to clock time.
Solstice and Equinox Shadows
The dial itself casts unique shadows on the solstices and equinoxes. On the solstices, the shadows of the equinox disk and the solstice ribbons of cones form a pattern of three ellipses. On the solstices, the top and bottom ellipses just kiss in the center. At local noon on the summer solstice, the solstice shadow cast by the dial crosses the shadow shape embedded in the sundial foundation.
During the winter solstice, a similar shadow is cast on the vegetation north of the dial.
On the equinoxes, the shadow cast by the dial consists of three parallel lines with the gnomon connecting them as shown below.
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