SUNDIAL

SUNDIAL
Although sundials can be traced back to earlier periods in Egypt and Mesopotamia, the earliest textual reference to a sundial appears to be II Kings 20:8–11 (cf. Isa. 38:7–8). There a shadow-tracking device, ascribed to Ahaz, is used for a sign that Hezekiah would be healed. The Masoretic Text speaks of ma'alot ahaz, literally "the steps of Ahaz." Various ancient versions and commentators disagree over whether the device is an actual sundial or a set of stairs attached to Ahaz's palace. Unfortunately, 1QIsaa, which contains the variant ma'alot 'lyt, does not resolve this question. A fragment of a portable, disk-shaped sundial excavated at Tel Gezer has been dated to the reign of Merneptah (1225–1215 B.C.E.) whose cartouches were inscribed on its back. Earlier representations of this type were found on the ceilings of the early 15th century tombs of Amenhotep I and Serenmuth. These appear as a circle subdivided by radiating lines into 24 equiangular sections. A later development, the sundial found at Qumran, was shaped like a shallow bowl with three circular dials and a small vertical gnomon in its center. The upper dial was divided into approximately 90 sections. The middle dial resembled those known from I Enoch 72, with 18 equiangular 20° "parts." This appears to be a shallow form of the hemisphaericum of Aristarchus described by Vitruvius (end first cent. B.C.E.). For the preceding two dials, since the increments were represented by equally spaced "steps" on each dial, and since the movement of the shadow of the gnomon travels faster at midday and slower at the day's beginning or end, the actual time that the shadow spent within each step varied accordingly. Also, the number of steps through which the shadow passed each day either increased or decreased depending on the season. The solstices, equinoxes, and months (or "gates") were tracked by noting where the first shadow of the gnomon became visible on the dial or by the rising of certain constellations at night. The latest and most common sundials were the typical Greco-Roman, quarter-spherical hemicyclium, and the "conical" conicum. Twelve equiangular sections on these dials measured hours which in real time varied both according to the time of the day and season. Three concentric circles, running perpendicular to the hour lines, marked the full extent of the shadow at the four cardinal points of the year. -BIBLIOGRAPHY: S. Adam, "Ancient Sundials of Israel," in: BSS Bulletin 14 (2002), 52–57, 109–114; Y. Yadin, "Ma'alot Ahaz," in: Eretz Israel 5 (1959), 91–96; pl. 10 (Heb.). (Stephen Pfann (2nd ed.)

Encyclopedia Judaica. 1971.

Look at other dictionaries:

  • Sundial — Sun di al, n. An instrument to show the time of day by means of the shadow of a gnomon, or style, on a plate. [1913 Webster] {Sundial shell} (Zo[ o]l.), any shell of the genus Solarium. See {Solarium}. [1913 Webster] …   The Collaborative International Dictionary of English

  • sundial — 1590s, from SUN (Cf. sun) + DIAL (Cf. dial) …   Etymology dictionary

  • sundial — ► NOUN ▪ an instrument showing the time by the shadow cast by a pointer …   English terms dictionary

  • sundial — [sun′dī΄əl] n. an instrument that indicates time by the position of a gnomon s shadow cast by the sun on the face of a dial marked in hours …   English World dictionary

  • Sundial — A sundial is a device that measures time by the position of the Sun. In common designs such as the horizontal sundial, the sun casts a shadow from its style (a thin rod or a sharp, straight edge) onto a flat surface marked with lines indicating… …   Wikipedia

  • sundial — /sun duy euhl, duyl /, n. an instrument that indicates the time of day by means of the position, on a graduated plate or surface, of the shadow of the gnomon as it is cast by the sun. [1570 80; SUN + DIAL] * * * ▪ timekeeping device  the earliest …   Universalium

  • sundial — UK [ˈsʌnˌdaɪəl] / US noun [countable] Word forms sundial : singular sundial plural sundials an object that measures time by the position of a shadow made in sunny weather, consisting of a pointed metal piece on top of a flat piece of stone …   English dictionary

  • sundial — [[t]sʌ̱ndaɪəl[/t]] sundials N COUNT A sundial is a device used for telling the time when the sun is shining. The shadow of an upright rod falls onto a flat surface that is marked with the hours, and points to the correct hour …   English dictionary

  • sundial — saulės laikrodis statusas T sritis Standartizacija ir metrologija apibrėžtis Tikrojo saulinio laiko matuoklis. Jį sudaro plokštuma su ciferblatu ir strypas arba plokštelė, kurių šešėlis krinta ant ciferblato. atitikmenys: angl. sundial vok.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • sundial — noun Date: 1599 an instrument to show the time of day by the shadow of a gnomon on a usually horizontal plate or on a cylindrical surface …   New Collegiate Dictionary

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