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 ?
Like the Witness in Gnomon, the Social Credit System promises that "everyone is equally seen."
After mounting the gnomon near the peak of his roof, he started marking points on the solstice, June 21st.
This paper began with the evidence that da Vinci had a global conceptualization of the world in his youth, and would most likely have encountered Paolo Toscanelli in his role in the leading bottega in Florence working at the Duomo at the same time as Toscanelli's gnomon. Now, as a cartographer, Toscanelli was in communication with the authorities in Portugal and Spain, and was reputed to have developed the (erroneous) map that inspired Columbus to set out to discover the western route to the Indies (which were known from the overland route through Asia).
Eventually, the core of the enigma consisted in the shape of gnomon resides in the removed part--in its absence or, so to say, the invisible, always imagined presence.
"Charles Williams on Taliessin Through Logres." Gnomon. issue number one (Fall 1965).
It stands on a large threetiered stone base on top of which is a cylindrical pedestal with a sloped cap engraved with a time conversion table supporting a stone cube with cast-iron gnomons (the feature that casts the shadow) on each side.
"shiftiness" of the gnomon in the image from The Trumpet
Once the Vikings had determined the position of the hidden sun, they could have used a specially designed wooden slab called a shadow stick to simulate the shadow of the gnomon based on the angle at which the hidden sun would hit it.
3, in which the gnomon is once again pointing to the South Celestial pole, whose shadow is cast onto a plane inclined at 15 [degrees] to the horizon.
Association of Jewelers and Diamond Manufacturers of Armenia, Head of the Yerevan Jewelry Plant "Gnomon", at during the Dec 13