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The Encyclopedia of Horology

Tool · Horizontal dial

Horizontal Dial

Partially verified

This unsigned horizontal dial, attributed to the late 16th century, is constructed of gilt copper and measures 110 x 72 x 85 mm. The object is designed in the shape of a casket with a hinged lid, supported by four bun feet. The main body of the instrument features various engraved tables and dials on its sides, including planetary and hour conversion scales. The top surface contains a central compartment housing a compass, surrounded by hour lines for a string gnomon dial. A second, smaller compartment is positioned on the lid. The interior of the lid is engraved with a 'CALENDARIVM PERPETVVM'. The instrument appears to have been part of a larger assembly, as the interior of the box contains rails for drawers, and other associated parts are currently lost. It was presented to the British Museum by A.W. Franks in 1871.

A horizontal dial casket of gilt copper with a hinged lid, featuring a compass, string gnomon dial, and various astronomical tables.
A horizontal dial casket of gilt copper with a hinged lid, featuring a compass, string gnomon dial, and various astronomical tables. — British Museum, London. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.mhs.ox.ac.uk
Category
Tool · Horizontal dial
Maker / attribution
Not established
Reference
MLA 1871, 11-15.5
Catalogue / lot identifier
MLA 1871, 11-15.5
Source-reported date
Late 16th century ?
Source-reported place
Netherlands

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 Exterior Form

The horizontal dial is manufactured from gilt copper and is formed as a rectangular casket, measuring 110 x 72 x 85 mm. The base of the casket rests upon four bun feet. The exterior surfaces are extensively utilized for horological and mathematical data.

The main lid features two supplementary compartments. The central compartment contains a compass and the markings for a string gnomon dial. The surface of the lid also includes latitude adjustment holes and various scales, including a calendar and degree markings.

Evidence for this section
  • “This brass dial is in the shape of a casket, with two supplementary compartments on the top.”
  • “The main part of the box stands on four bun feet, and is at present empty but has inside rails for drawers.”
  • “At the centre of the lid plate is a compartment, with linear decoration on the sides, with a compass in the centre.”

Tables and Astronomical Data

The sides of the box are engraved with a series of tables for planetary calculations and the conversion of various hour systems. These include a 'Tabula Planetarii' on the north side, which lists planetary symbols and names, and the hours of the day and night.

The east and west sides contain complex conversion tables. These allow for the conversion of common hours into Italian hours or unequal planetary hours based on the time of sunset, identified as 'Occasus'. Additionally, the south side of the instrument bears a multiplication table.

Evidence for this section
  • “The sides of the box are engraved with dials and tables.”
  • “On the north side is a table inscribed 'Tabula Planetarii', 'Hora<e> diei', 'Hora<e> noctis'.”
  • “The east side of the box has a table, inscribed 'maius et minus Horologium Oppositum et ad aequatium', for converting common hours into Italian hours, according to the time of sunset.”
  • “The south side of the box has a table of multiplication of the numbers from 1 to 10.”

Internal Features and Provenance

The inside of the lid is engraved with a perpetual calendar listing specific saints' and holy days throughout the year. The lid also incorporates brass bands and scales for determining day length and solar rise or set times.

The object is currently housed at the British Museum and was donated by A.W. Franks in 1871. The interior of the main box is currently empty, though it retains rails originally designed to accommodate sliding drawers.

Evidence for this section
  • “The inner part of the lid is engraved with a 'CALENDARIVM PERPETVVM' in the central part, indicating some saint's and holy days' dates.”
  • “The instrument was presented by A.W. Franks in 1871”
  • “The main part of the box stands on four bun feet, and is at present empty but has inside rails for drawers.”

Open research questions

  • What was the specific function of the empty internal rails and the missing drawer components?
  • Can the origin of the latitude settings 49, 50, and 51 be reconciled with the attributed Dutch provenance?
  • What is the identity of the monogram engraved beneath the latitude adjustment holes?

Source evidence

Recorded claims and source quotations for Horizontal Dial
FieldSource-reported valueSource quotation
MaterialGilt copper“Gilt copper”
Dimensions110 x 72 x 85 mm“110 x 72 x 85 mm”
AttributionUnsigned; Dutch; Late 16th century“Unsigned Late 16th century ?; Dutch”
Inventory NumberMLA 1871, 11-15.5“MLA 1871, 11-15.5”
ProvenancePresented by A.W. Franks in 1871“The instrument was presented by A.W. Franks in 1871”
Calendar FeatureInternal lid engraved with 'CALENDARIVM PERPETVVM'“The inner part of the lid is engraved with a 'CALENDARIVM PERPETVVM' in the central part”

Visible details

  • The instrument is shaped like a casket standing on four bun feet.
  • The interior of the lid is engraved with a perpetual calendar.
  • The sides are densely engraved with conversion tables, including multiplication tables and hour-system converters.
  • The top surface includes a compass and hour markings for a string gnomon dial.

Research qualifications

  • The date is qualified with a question mark by the source.
  • The function of one of the supplementary lid compartments is described as not clear.
  • The string gnomon for the dial is missing.

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

Consulted source

Horizontal Dial

Reviewed 2026-10-26 · Record 92c5f5f90f

Terms in this record

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

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