Clock · Pocket horizontal sundial

Ansonia Sunwatch (pocket compass dial)

Partially verified

According to the Science Museum Group, this pocket horizontal sundial known as the Sunwatch was manufactured between 1922 and 1939 in New York county by the Ansonia Clock Company. Built within a hinged rectangular metal pocket case, the instrument incorporates a folding metal gnomon, concentric hour scales calibrated for latitudes 51, 54, and 57, and an integrated magnetic compass. A reference card inside the upper lid provides latitude, longitude variation, and equation of time adjustments for numerous locations across the British Isles.

Interior view of the opened Ansonia Sunwatch showing the sundial plate, compass, and reference table in the lid — Science Museum Group. Rights pending — permission not yet requested. Original source

Catalogue identity

Source: collection.sciencemuseumgroup.org.uk
Category: Clock · Pocket horizontal sundial
Maker / attribution: Ansonia Clock Company
Reference: Not recorded
Catalogue / lot identifier: 1974-100
Source-reported date: 1922-1939
Country: United States

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

Object Classification and Physical Case

According to the Science Museum Group, this instrument is catalogued under the category of Time Measurement as a pocket horizontal sundial under object number 1974-100. Recorded as having been made between 1922 and 1939 in New York county by the Ansonia Clock Company, the device is housed in a rectangular folding format.

Physical observation shows a hinged rectangular metal case opened to reveal an integrated printed paper chart inside the upper lid titled 'TABLES OF LATITUDES ETC. EQUATION'. In the supplied photograph, the exterior of the case is not visible, leaving any outer surface markings or finishes unrecorded.

Evidence for this section

“Category: Time Measurement”
“type: pocket horizontal sundial”
“Object Number: 1974-100”
“Made: 1922-1939 in New York county”
“maker: Ansonia Clock Company”
“Hinged rectangular metal case opened to reveal an integrated printed paper chart inside the upper lid titled 'TABLES OF LATITUDES ETC. EQUATION'.”

Dial Plate and Gnomon Construction

The dial plate inside the opened lower case features concentric hour tracks marked for latitudes 51, 54, and 57, an integrated circular magnetic compass, and a central folding metal gnomon. In the provided photograph, the gnomon is laid flat rather than erect.

The lower rim of the dial plate is stamped 'MANUFACTURED BY THE ANSONIA CLOCK CO. U.S.A. / PATENT SUNWATCH PENDING', identifying the maker and model name as well as indicating patent-pending status at the time of manufacture.

Evidence for this section

“Dial plate features concentric hour tracks marked for latitudes 51, 54, and 57, a central folding metal gnomon laid flat, and a circular magnetic compass.”
“The lower rim of the dial is stamped 'MANUFACTURED BY THE ANSONIA CLOCK CO. U.S.A. / PATENT SUNWATCH PENDING'.”

Museum Record and Provenance

The Science Museum Group records the acquisition credit for this object as 'Frye, I.' under object number 1974-100.

The museum record does not detail the physical condition of the compass pivot or the functional operation of the folding gnomon beyond what is visibly recorded in the photograph.

Evidence for this section

“credit: Frye, I.”
“Object Number: 1974-100”

Open research questions

What markings, case metal finish, or decorative elements are present on the exterior covers of case 1974-100?
Which specific patent was pending for the Sunwatch, and was a patent subsequently granted to the Ansonia Clock Company?
Does the magnetic compass needle retain free movement on its pivot when the case is held horizontally?

Source evidence

Recorded claims and source quotations for Ansonia Sunwatch (pocket compass dial)
Field	Source-reported value	Source quotation
Maker	Ansonia Clock Company	“maker: Ansonia Clock Company”
Date	1922-1939	“Made: 1922-1939”
Place Made	New York county	“in New York county”
Object Number	1974-100	“Object Number: 1974-100”
Type	pocket horizontal sundial	“type: pocket horizontal sundial”
Museum Credit	Frye, I.	“credit: Frye, I.”
Museum Category	Time Measurement	“Category: Time Measurement”

Visible details

Hinged rectangular metal case opened to reveal an integrated printed paper chart inside the upper lid titled 'TABLES OF LATITUDES ETC. EQUATION'.
Dial plate features concentric hour tracks marked for latitudes 51, 54, and 57, a central folding metal gnomon laid flat, and a circular magnetic compass.
The lower rim of the dial is stamped 'MANUFACTURED BY THE ANSONIA CLOCK CO. U.S.A. / PATENT SUNWATCH PENDING'.

Research qualifications

The exterior of the case is not visible in the supplied photograph.
The central gnomon is shown in its folded position rather than erect.

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

Consulted source

Ansonia Sunwatch (pocket compass dial) | Science Museum Group Collection

Reviewed 2026-10-21 · Record bcba62ff6b

Terms in this record

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