Nocturnal and Quadrant

Technical characteristics

Date

1543

Type

French nocturnal and quadrant

Origin

French

Dimensions

71 mm

Place recorded

France

Quadrant Markings

Shadow square marked with French labels

Moon Phase Function

A circular aperture reveals the phase of the moon.

Design

Visible features

• Pinhole sights on quadrant side • Moveable volvelle with circular aperture for moon phase • Signs of Ptolemaic planets on rotating disc • Engraved scrolls with 1543 date

Nocturnal Functionality

The nocturnal side of the brass instrument is configured to determine the time at night based on stellar positioning. It utilizes a zodiac scale that displays the names of constellations, each further divided into segments of 1/6 and 1/30. An interior scale numbered 1 to 28 complements the zodiac markings. To facilitate the calculation of time and lunar cycles, the instrument features a moveable volvelle disc. This disc carries an index arm that extends across the zodiac scale and provides a dual-12 hour scale, with night hours specifically indicated by points. Furthermore, a moon-age scale, divided from 1 to 20, is integrated onto the component. A second disc, marked with the signs of the Ptolemaic planets, features a circular aperture designed to reveal the current phase of the moon.

Condition and Identification

The instrument is catalogued by the Museum of the History of Science in Oxford under inventory number 55203. It is currently unsigned by any maker. The attribution of the object as French and the date of 1543 are provided by the museum's documentation of the piece. The physical condition of the object is noted by the museum, specifically identifying the absence of the plumb-line weight. Despite the small diameter of 71 mm, the instrument is densely packed with multiple overlapping scales, lines, and functions, including various zodiac scales and hour markers intended for different astronomical applications.

Quadrant and Horary Functions

The reverse of the instrument functions as a multifaceted horary quadrant. It is equipped with two pinhole sights and a plumb-line, though the weight originally associated with the latter is currently missing. The quadrant incorporates a degree scale from 0 to 90 and a shadow square numbered 0 to 12. The instrument also features the lines of the quadrans vetus and a separate set of ordinary hour lines. These functions are used in conjunction with a solar declination scale marked with zodiac signs. A specific line designated as 'LORIZON DE SOLEIL LEVANT' indicates sunrise and sunset, while three engraved scrolls are present on the device, one of which contains the inscribed date of 1543.

Identification

Inventory Number

55203

Source note

Facts transcribed from the linked source listing or collection record. Attribution and specifications are source-reported and have not been independently authenticated.

Catalogue references

No catalogue numbers recorded. Numbers are only published once transcribed from a verified edition of a standard catalogue — they are never inferred.