Pocket watch · Verge calendar watch with sundial

Oval gilt-brass and silver cased verge watch with calendar dial and sundial

Partially verified

This early seventeenth-century oval watch is reported by the British Museum to have been made by Coenrad Jacobs in Leeuwarden between 1610 and 1620. Constructed with a gilt-brass case featuring an applied silver foliate band, the interior lid retains a removable horizontal sundial with a folding gnomon and central orientation compass. The gilt-brass dial plate exhibits foliate scroll engraving, an applied silver chapter ring with touch-pins, concentric rings for the date and moon's age, and a central aspectarium displaying lunar phase indications. The movement incorporates a fusee, three-wheel going train, and a pre-balance spring verge escapement.

Open view of the oval verge watch showing the dial indications and the internal sundial and compass mounted inside the lid — British Museum. Rights pending — permission not yet requested. Original source

Catalogue identity

Source: www.britishmuseum.org
Category: Pocket watch · Verge calendar watch with sundial
Maker / attribution: Coenrad Jacobs
Reference: 1888,1201.176
Catalogue / lot identifier: Source URL identifies the listing
Source-reported date: 1610-1620
Country: 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

Case and Integrated Sundial

The object is an oval gilt-brass case featuring an integral plain back and an applied silver band decorated with foliate scrolls.

The interior of the lid contains a removable horizontal sundial, which is equipped with a folding gnomon and a central compass for orientation.

Evidence for this section

“Oval gilt-brass case with integral plain back and an applied silver band decorated with foliate scrolls.”
“Inside the lid ia a removeable horizontal sundial with folding gnomon and a compass in the centre for orientation.”

Dial Configuration

The gilt-brass dial plate is decorated with foliate scroll engraving. It includes an applied silver chapter ring featuring Roman numerals (I-XII), star half-hour marks, and touch-pins at the hours.

The dial includes a gilt-brass ring calibrated 1-31 for the date and a silver ring calibrated 1-29½ for the moon's age, with a central aspectarium aperture to display lunar phases.

Evidence for this section

“Gilt-brass dial plate with foliate scroll engraved ornament around the outside. Applied silver chapter ring with hour I-XII, star half-hour marks and touch-pins at the hours.”
“Within the chapter ring a gilt-brass ring calibrated 1-31 for the date. Within this a silver ring calibrated 1-29½ for the moon's age. At the centre an engraved aspectarium with an aperture to show the phase of the moon.”

Movement and Mechanism

The movement features oval gilt-brass plates with four baluster pillars, a fusee with standard stop-work, a three-wheel going train, and a pre-balance spring verge escapement with a two-arm steel balance.

The motion work is driven by an integral pinion on the fusee/great-wheel arbor. The lunar disc and date-ring are friction-tight to allow for user adjustment.

Evidence for this section

“Oval gilt-brass plates with four baluster pillars.”
“Verge escapement with two-arm steel balance.”
“The moon's phase does not, of course, keep step with the months and so when setting the watch the user would first set the friction-tight date-ring correctly, and then the friction-tight lunar disc.”

Open research questions

What are the technical specifications for the 'three-wheel going train' used in early 17th-century verge watches?
How does the motion work on this specific movement compare to other examples of Coenrad Jacobs' work?

Source evidence

Recorded claims and source quotations for Oval gilt-brass and silver cased verge watch with calendar dial and sundial
Field	Source-reported value	Source quotation
Maker	Coenrad Jacobs	“Made by: Coenrad Jacobs”
Production Place	Leeuwarden	“Made in: Leeuwarden”
Production Date	1610-1620	“1610-1620”
Escapement	pre-balance spring verge	“pre-balance spring verge”
Museum Number	1888,1201.176	“1888,1201.176”
Maker	Coenrad Jacobs	“Made by: Coenrad Jacobs”
Production Place	Leeuwarden	“Made in: Leeuwarden”
Production Date	1610-1620	“1610-1620”

Visible details

Hinged lid opened to display an internal horizontal sundial with a central compass and folding gnomon.
Main dial plate features engraved scrolling foliage surrounding an applied silver Roman numeral chapter ring with star half-hour markers and touch-pins.
Inner dial contains calibrated concentric rings for dates 1 to 31 and moon's age 1 to 29½, enclosing a central aspectarium disc.
Visible case band shows an applied pierced or chased dark silver scrollwork band on the gilt-brass body.

Research qualifications

Source notes the sundial inside the lid is removable.
Country of origin is reported as Leeuwarden (modern-day Netherlands).

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

Consulted source

calendar watch; sundial watch; watch-case | British Museum

Reviewed 2026-10-25 · Record 9ca4329f1b

Terms in this record

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