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The Encyclopedia of Horology

Tool · Italian horizontal dial

Horizontal Dial by Carlo Plato

Partially verified

This horizontal dial is a circular brass instrument, 75 mm in diameter, attributed to the maker Carlo Plato of Rome and dated 1588. The device features a central aperture for a pivoted compass, though the magnetic needle is currently missing. The instrument is designed for use on either side of the brass plate. One face contains two pin-gnomon dials calibrated for Italian hours across latitudes 42° and 45°, supplemented by inscriptions designating the location as Rome and listing wind directions in Italian around the border. The reverse side holds four additional pin-gnomon dials configured for various latitudes, including 36° and 48°, and incorporates both Italian and common hour markings.

Horizontal dial, brass, dated 1588, attributed to Carlo Plato of Rome.
Horizontal dial, brass, dated 1588, attributed to Carlo Plato of Rome. — 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 · Italian horizontal dial
Maker / attribution
Carlo Plato
Reference
Not recorded
Catalogue / lot identifier
46744
Source-reported date
1588
Source-reported place
Italy

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 Design

The instrument is a circular brass plate measuring 75 mm in diameter. It is designed to be used on either side, featuring a central void which originally housed a pivoted compass, though the needle is now lost.

The plate is densely engraved with multiple pin-gnomon dials, allowing for time calculation across varying latitudes. The borders of both sides are annotated with the names of winds, including 'Lev ate', 'Si rocco', and 'Tramo tana', providing orientation data for the user.

Evidence for this section
  • “The dial consists of a circular brass plate with a pivoted compass (needle missing) in the centre.”
  • “on the border of the plate are engraved the names of the winds 'Lev ate', 'Si rocco', 'Os tro', 'Gar bino', 'Pon ete', 'Mae stro', 'Tramo tana', 'Gre co'.”

Dial Calibration and Usage

The dial is configured for diverse geographical applications. One side includes dials for latitudes 42° and 45°, specifically marked 'Polus 42 Gra duum' and 'Ad Latitudine Graduu 45', serving Italian hours ranging from 9 to 23.

The reverse side hosts four additional dials for latitudes 36° and 48°. These displays include markings for common hours as well as Italian hours, demonstrating the instrument's capacity to convert between different timekeeping systems depending on the user's location.

Evidence for this section
  • “On one side of the plate are two pin gnomon dials for Italian hours numbered from 9 to 23, for the latitudes 42? and 45?”
  • “The second dial marks Italian hours (marked from 9 to 19) and common hours (marked from 6 to 12) for the latitude 48?”

Attribution and Provenance

The dial is held by the Museum of the History of Science, Oxford, under inventory number 46744. It is formally attributed to the Roman maker Carlo Plato based on its similarity to other catalogued instruments in the museum's collection.

The specific inscription 'Roma anno 1588' provides a confirmed production date and suggests the location of the maker during the time of the instrument's manufacture.

Evidence for this section
  • “This dial, which is very similar to Epact 37081, has been attributed to the same maker, Carlo Plato of Rome.”
  • “Another inscription reads 'Roma anno 1588'”

Open research questions

  • What is the specific functional purpose of the compass if it was designed to be pivoted on both sides?
  • Are the remaining pin-gnomons original to the plate's construction?

Source evidence

Recorded claims and source quotations for Horizontal Dial by Carlo Plato
FieldSource-reported valueSource quotation
Object typeHorizontal Dial“Horizontal Dial”
MakerCarlo Plato“Attributed to Carlo Plato”
Date1588“Dated 1588”
Dimensions75 mm diameter“75 mm in diameter”
OriginItaly“Italian”
Accession number46744“Inventory number: 46744”

Visible details

  • The central compass housing is present but lacks the magnetic needle.
  • Multiple pin-gnomon positions are visible on the plate surface for different latitudes.
  • Engraved wind names are located around the outer border of the plate.
  • The instrument is constructed from a thin circular brass plate.

Research qualifications

  • The magnetic compass needle is explicitly noted as missing.
  • The attribution to Carlo Plato is based on stylistic comparison to other instruments, not a signature on this specific piece.

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

Consulted source

Horizontal Dial

Reviewed 2026-10-26 · Record 764fd0e75b

Terms in this record

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

Other italian horizontal dial records