The top of each column has a hole for inserting the shadow-casting gnomon, a peg.
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According to the Zhouli the original feng shui instrument may have been a gnomon.
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The point where the style intersects the dial plate is called the gnomon root.
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As with the gnomon, the hour-lines are all aligned with the Earth's rotational axis.
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The ends of the gnomon bar may be used as the nodus, or some feature along its length.
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Other non-planar surfaces may be used to receive the shadow of the gnomon.
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The folding triangular gnomon is supported by a decorative open-work motif.
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The art of constructing a gnomon sundial is sometimes termed gnomonics.
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Shepherd's dials are sometimes hollow, so that the gnomon can fold within when not in use.
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More examples
Indicator provided by the stationary arm whose shadow indicates the time on the sundial
A gnomon (, from Greek u03B3u03BDu03CEu03BCu03C9u03BD, gnu014Dmu014Dn, literally: "one that knows or examines") is the part of a sundial that casts a shadow.
In geometry, a gnomon is a plane figure formed by removing a similar parallelogram from a corner of a larger parallelogram. More generically, the term gnomon denotes the form that is to be added to a figure to produce a larger figure of the same shape.
Tool consists of a weighted staff suspended on a two-ring gimbal and supported by a tripod. The staff extends 12 inches above the gimbal and is painted with a gray scale. The gnomon is used as a photographic reference to indicate local vertical, sun angle, and scale
The pointer (stick) on a sundial, which by its shadow, shows the hour of the day. It is usually set parallel to the earth's axis.
A column that can indicate the time of day by the shadow that it casts on a marked surface. On a sundial, the pin or vertical triangular plate that casts the shadow is called a gnomon. More information can be found at Design of the Richard D. ...
Vane or indicator casting a shadow onto a sundial.