gnomon


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gnomon

(nō`mŏn): see sundialsundial,
instrument that indicates the time of day by the shadow, cast on a surface marked to show hours or fractions of hours, of an object on which the sun's rays fall.
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gnomon

(noh -mon) A device used in ancient times to measure the altitude of the Sun and hence to determine the time of day and time of year. It consisted of a vertical shaft of known height (such as an upright rod or pillar) that cast a shadow of measurable length and direction on a graduated horizontal base. The ratio of height to shadow length gave the tangent of the altitude angle. The term is also applied to the metal projection on a sundial, used for the same purpose.

Gnomon

 

an ancient astronomical instrument consisting of a vertical column on a horizontal platform. The altitude and azimuth of the sun can be determined from the length and direction of the column’s shadow. The shortest shadow during the day indicates the direction of the north line. In ancient times the gnomon was used to determine the inclination of the ecliptic to the equator and the geographical latitude of locations. In modern times the gnomon finds use only as a sundial.

gnomon

[′nō·mən]
(engineering)
On a sundial, the inclined plate or pin that casts a shadow. Also known as style.
(mathematics)
A geometric figure formed by removing from a parallelogram a similar parallelogram that contains one of its corners.
References in periodicals archive ?
this is reproduced almost verbatim in "Notes on the Arthurian Myth" 179 and in Gnomon 41-42)
Their location in a freely accessible public park dictated material choice to be as vandalproof as possible: Engraved polished granite for the sundial faces, gnomons as small as possible in stainless steel and explanatory plaques firmly epoxied onto a sandstone-dressed plinth that matches the style of the benches and other structures in the park.
A similar plot of the Yujitu vertical coordinate against the tangent of latitude does not fit quite as well, confirming that the angular altitudes of heavenly bodies, not gnomon shadow lengths, were used to position features in the north-south axis.
79 metres in height and weighing 230 tonnes, was placed as a gnomon or pointer in the Horologium Divi Augusti, the emperor's monumental sundial in the Campus Martius near the Ara Pacis and Mausoleum.
Occupation: Vice president, Gnomon Inc, 1999 to present.
It measures the time of day by the sun's altitude with a gnomon that fits into appropriately placed holes (Canterbury Cathedral).
Neither nostalgic for the past nor unduly confident that it may be understood, Stephen Greenblatt's sentence serves Pieters as a gnomon of New Historicist assumptions about interpretation.
Before clocks were invented, some people kept track of time by watching a shadow move across a carved piece of stone called a sundial A needle, or gnomon (NOH-mahn), cast a shadow that crossed the dial's marks one by one as the sun moved from east to west overhead.
Alleghany County Farmers' Market Intersection, NC 18N and Gnomon St, Sparta, NC sat 8am-12pm
With backgrounds in "fringe" photography, such as holography and photogrammetry, and in visual effects--the two met as instructors at the Gnomon School of Visual Effects in Hollywood, Calif.
If the gnomon is 20 m high (at 45[degrees] of latitude), the difference on the line is about 25 cm, this means that it is possible to know the moment of the equinox within half an our if the edge of the image is about 1 cm.
Toronto: Anansi; Frankfort, Kentucky: Gnomon, 2004.