Images(5)

sundial

Object NameGrand Universal Equinoctial Dial with Precision Oculus

Maker Pierre Mégnié (French, fl. 1751-1807)

Made FromBrass, Glass

Dateabout 1790

TechniqueRolled, ground, polished

SizeClosed H: 4.6 cm, W: 21.5 cm, D: 21 cm; Open H: 14. 5

Accession Number2018.8.2

Curatorial Area(s)

Place Made

Spain, Madrid

Physical DescriptionGrand Universal Equinoctial Dial with Precision Oculus. Rolled brass, ground and polished glass lens. Brass horizontal sundial with main plate measuring 19.5 x 21 cm, set with three leveling screws, crossed spirit levels, and freely rotatable central circular dial plate. The latter is set with a large hinged chapter ring engraved with scales in both Roman and Arabic numerals, divided every five minutes from 4 am to 8 pm. This equinoctial ring is inclined against a hinged latitude arc divided every half-degree 0° to 70°. The hour ring has a crossbar carrying the gnomon, which swivels flat for stowage, upwards for summer when the sun is above the celestial equator, and downwards for winter. Rather than the typical needle gnomon, there is an oculus with a tiny lens, swiveling and adjustable vertically for solar declination from 0° to 23-1/2°, with readout by a grid of transversals to five arcminutes.
Provenance

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