The first device for indicating the time of day was probably the gnomon, dating from about 3500 bce. It consisted of a vertical stick or pillar, and the length of the. A horizontal sundial consists of the dial plate, marked off in hours, and the gnomon which sits on the noon line and projects out from the. These were usually used in former times for observing the altitude of the sun, especially when on the meridian. The angle of the gnomon corresponds to the latitude at which the sundial is sited. For example if the sundial was to be sited at greenwhich london that has a. The gnomon is a scientific instrument that can be used for finding the declination of the sun through the year, among other things.
This month i discuss the subtle difference in meaning between gnomon and style. Figure 1 shows a side view of the essential parts of a horizontal sundial, for a. Description the simplest sundial consists of two parts a flat plate and a gnomon (or stick) that casts a shadow on the. Set the gnomon (thats fancy for the part that sticks up), so that its facing true north. If youve set your sundial correctly (and its noon100. We consider here the analemmatic sundial with a gnomon that moves on a calendar line (or zodiac walkway) while remaining perpendicular to. .