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The Encyclopedia of Horology

Tool · Flemish nocturnal and sundial

Nocturnal and Sundial by Michiel Coignet

Partially verified

This brass instrument, 108 mm in diameter, is signed by the mathematician and instrument maker Michiel Coignet and dated 1598. It is a dual-purpose tool featuring a nocturnal on one side and an 'organum Ptolemai' altitude sundial on the reverse. The nocturnal base-plate contains latitude correction scales, a zodiacal calendar, and a solar declination scale. Above this, volvelle plates facilitate the calculation of hours and the date of Easter, which is marked 'Epacte Anno. 98'. The index arm is engraved with 'Quadrang. vrse minoris'. The sundial side features a Rojas projection of the celestial sphere, set using a latitude scale and polar index points. The handle is engraved with various city names and their latitudes. The object was acquired as part of the Lewis Evans Collection by the Museum of the History of Science, Oxford.

A brass nocturnal and altitude sundial by Michiel Coignet, 1598, showing the volvelle plates, zodiacal calendar, and index arm.
A brass nocturnal and altitude sundial by Michiel Coignet, 1598, showing the volvelle plates, zodiacal calendar, and index arm. — Museum of the History of Science, Oxford. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.mhs.ox.ac.uk
Category
Tool · Flemish nocturnal and sundial
Maker / attribution
Michiel Coignet
Reference
Not recorded
Catalogue / lot identifier
44721
Source-reported date
1598
Source-reported place
Antwerp

Source-reported attribution and specifications are not independent authentication. A listing does not establish present ownership, current display, availability or permission to reproduce.

Object description

Construction and Nocturnal Function

The instrument is a brass disc measuring 108 mm in diameter. One side functions as a nocturnal, used for timekeeping at night. The base-plate includes an outermost scale with divisions for latitude corrections, used when the instrument is held vertically and the index arm is aligned with Ursa Minor.

Moving inward from the edge, the base-plate contains a zodiacal calendar with signs and symbols, and a solar declination scale. A series of volvelle plates are mounted above this, featuring an hour scale from 4 pm to 12 to 8 am. The hour plate includes a specific inscription for calculating the date of Easter.

Evidence for this section
  • “The outermost scale on the nocturnal base-plate has four divisions for each quadrant”
  • “the nocturnal held vertical and the index arm coinciding with Ursa Minor”
  • “inner scale of numbers marked 'Epacte Anno. 98' for calculating the date of Easter”

Sundial and Celestial Projection

The reverse side functions as an 'organum Ptolemai' altitude sundial. It incorporates a latitude scale marked 0 to 90 degrees twice. This side utilizes two polar index points, one designated 'Polus arcticus', which are connected by an 'Axis mundi' line.

A volvelle plate on this side features a Rojas projection of the celestial sphere. This grid contains parallel lines for solar declination and curved hour lines. A sighting rule and a right-angle index pivot around a central rivet to allow for solar time calculation.

Evidence for this section
  • “the 'organum Ptolemai' form of altitude sundial on the reverse”
  • “volvelle plate carrying a Rojas projection of the celestial sphere between the tropics”
  • “A sighting rule and right-angle index pivot together around the pierced rivet”

Provenance and Documentation

The instrument is signed 'Michael Coignet fe' on the reverse of the index. The handle of the instrument is engraved with various cities and their corresponding latitudes. These additions reflect Coignet's role as a mathematician in Antwerp.

The object is part of the Lewis Evans Collection, specifically catalogued as G. 78. It has been documented in scholarly literature, specifically in 'The Measurers: A Flemish Image of Mathematics in the 16th Century' by Jim Bennett.

Evidence for this section
  • “Each side of the handle is engraved with city names and latitudes”
  • “The instrument was acquired with the Lewis Evans Collection (Lewis Evans G. 78)”

Open research questions

  • What is the specific historical significance of the 'organum Ptolemai' design?
  • How do the engraved city latitudes compare to modern geographic coordinates?

Source evidence

Recorded claims and source quotations for Nocturnal and Sundial by Michiel Coignet
FieldSource-reported valueSource quotation
MakerMichiel Coignet“Signed by Michiel Coignet”
Date1598“Dated 1598”
LocationAntwerp“Antwerp”
Diameter108 mm“108 mm in diameter”
Inventory Number44721“Inventory number: 44721”
SignatureMichael Coignet fe“The instrument is signed on the reverse of the index 'Michael Coignet fe'.”

Visible details

  • Handle engraved with city names and associated latitudes
  • Nocturnal index arm engraved with 'Quadrang. vrse minoris'
  • Volvelle plate marked 'Epacte Anno. 98'
  • Constructed of brass with a 108 mm diameter

Research qualifications

  • Attribution to the Flemish school of the 16th century is context-based
  • Stylistic relationship to the workshop of Gualterus Arsenius is suggested but not definitively established by the source

Photograph identity and source facts were screened before import; rights clearance remains pending.

Consulted source

Nocturnal And Sundial

Reviewed 2026-10-26 · Record 9f7a5185ca

Terms in this record

Glossary explanations for terms named in this object’s record.