Glossary · Mechanism
Gnomon
The fixed projecting element of a sundial whose shadow indicates the time.
Explanation
The gnomon is the part of a sundial that casts the shadow. On an accurate sundial its shadow-casting edge (the style) is parallel to the Earth's axis, so it is set at an angle equal to the local latitude. Sundials show apparent solar time, which differs from mean clock time by the equation of time and from civil time by longitude and time-zone offset.
In the object catalogue
Catalogued objects whose own source record mentions “Gnomon”. The quoted line shows where; it is the seller’s or museum’s wording, not independent verification.
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Ansonia Sunwatch (pocket compass dial)
“According to the Science Museum Group, this pocket horizontal sundial known as the Sunwatch was manufactured between 1922 and 1939 in New York county by the Ansonia Clock Compan…”
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Diptych sundial for latitude 47 degrees
“This ivory diptych sundial was made by Hanns Troschel in Nuremberg between 1623 and 1628 for use at latitude 47 degrees, as recorded by the Science Museum Group. The instrument …”
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Portland Stone Sundial
“This early 19th-century garden sundial consists of an inscribed dial plate mounted upon a baluster-form Portland stone pedestal. According to the auction catalogue, the dial pla…”
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Beringer and Seyfried Polyhedral Sundial
“The National Museum of American History preserves this wooden polyhedral cube dial, attributed by the source to David Beringer and Georg Paulus Seyfried in Nuremberg, Germany, d…”
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Parisian silver Butterfield travel sundial
“This lot features an octagonal Parisian silver travel sundial signed 'Butterfield AParis' on the plaque, dated by the auction house to the last quarter of the 18th century. Name…”
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David Beringer single-latitude sundial, circa 1780
“The source reports that this engraved brass single-latitude sundial dates to circa 1780 and is attributed to David Beringer based on an engraved 'B' mark. The dial is mounted on…”