"Sungames" in Sestri Levante (Genova) - Part 1
Latitude 44° 16' 17" N - Longitude 9° 24' 23" E
Hindu Circles (equal altitude sundial)
This simple astronomical instrument is a sundial that allows to identify the meridian line with a good approximation. On the floor there are six concentric circles of gradually increasing radius which delimit five circular sectors of different colors; in the circle common center there is a vertical rod steel: the gnomon. This sundial requires a sunny day and plenty of time; in a sunny morning (one or two hours before noon) when the shadow cast by the gnomon touches one of the circles, we immediately lean an object that can serve as a marker (i.e. a pebble) at the point of tangency. After solar noon we wait until the gnomon shadow will touch the same circle on the opposite side and mark this point with a second pebble. As the Sun passes through the same circle in the morning and afternoon it will be at the same altitude. To identify the true North-South (meridian) line we locate the angle bisector between the rays that connect the two mark points found with the circle center. For a better determination we can take measurements on different days or, in the same day, take note of mark points of more than one circle. At solar noon the shadow of the gnomon is in the direction of the meridian line.
Horizontal Sundial (Cord sundial)
In this sundial the gnomon, a movable nylon cord, is set by the observer so that it, and its shadow, lie in the Sun's hour plane. This sundial recalls the link between Sestri Levante and the sea: a bollard, used for mooring ships, anchored to the pylon of a jetty, and a Dawn Treader in the middle of the dial, that has also sixteen red painted hour points. To read local apparent time on this sundial, the user must hold the free end of the gnomon cord taut and move it until its shadow falls across the center of the dial: the yellow circle in the center with the Dawn Treader.
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