Theodolite and sundial
Record status
Individual type · partial
Period
circa 1570
This 364 mm square brass instrument consists of a square base plate with a revolving disc containing an integrated sundial and theodolite. It is attributed to the maker Gualterus Arsenius, working in Louvain around 1570.
The plate features a shadow square marked 'VMBRA RECTA' and 'VMBRA VERSA', a scale of degrees from 0 to 360, and a wind rose with 32 directions named in Dutch. The revolving disc, which includes an open quadrant, incorporates hour lines for a horizontal dial adaptable for latitudes 30 to 63 degrees. A central compass bowl, currently lacking its needle and glass, includes a degree scale and Italian wind labels. The reverse side features a cylindrical mounting socket, two suspension rings, and an earlier, now unusable, quadrant graduation.
This object is one of several instruments associated with this specific technical design, mirroring features found on other tools of the period.
Evidence at a glance
- Linked sources
- 1
- Photograph views
- 1
- Catalogue references
- 0
Counts describe this entry’s documentation, not authenticity, rarity or completeness. Photographs may show one specimen; check each caption and licence.
Technical characteristics
- Date
- circa 1570
- Type
- Other scientific instrument
- Maker
- Attributed to Gualterus Arsenius
- Compass
- 73 mm in diameter
- Location
- Louvain
- Wind Rose
- 32 directions named in Dutch
- Dimensions
- 364 mm square
- Place recorded
- Louvain
- Maker / attribution
- Attributed to Gualterus Arsenius
Design
- Visible features
- • Square brass plate marked with corner letters A, B, C, and D • Central circular compass bowl with a 73 mm diameter • Revolving disc with an open quadrant and hour line markings • Two suspension rings fixed to the edges of the plate
- Sundial and Compass Features
- The revolving disc provides the functionality for a horizontal sundial, with hour lines calibrated for latitudes between 30 and 63 degrees. Declination lines are provided for each degree of latitude. The hours are divided into morning and afternoon sections, with quarter-hour incisions marked on every third declination line. Although the exact construction of the gnomon is not fully determined, a string-based design is proposed. Located in the center of the disc is a compass bowl, 73 mm in diameter. It includes a degree scale from 0 to 90 and indicates the principal Italian winds. A magnetic variation of approximately 9 degrees east is noted on the instrument. The needle and protective glass are currently absent from the assembly.
- Construction and Plate Layout
- The instrument is composed of a 364 mm square brass plate, designed with a revolving disc mechanism. Each corner is marked with the letters A, B, C, and D. The plate contains four circular scales, including an outer shadow square labeled 'VMBRA RECTA' and 'VMBRA VERSA' in each corner, alongside a 0-360 degree scale. The plate also incorporates a wind rose featuring 32 directions labeled in Dutch, with cardinal points marked in Latin. A corresponding scale of 0-32 surrounds this, complemented by a simpler, ungraduated 32-part inner scale. The reverse side contains a cylindrical socket intended for post mounting and two suspension rings, as well as an earlier quadrant scale that can no longer be used due to subsequent modifications.
- Attribution and Comparative Context
- The instrument is unsigned, but scholars have attributed it to Gualterus Arsenius, active in Louvain circa 1570. The design, which combines a square theodolite with a revolving sundial disc, shares characteristics with a signed example currently held in the Württembergisches Landesmuseum in Stuttgart. The instrument's design philosophy is similar to work by other Flemish makers, such as Petrus ab Aggere, who produced theodolites of a comparable type, though without the integrated sundial feature. The inclusion of an abandoned quadrant on the reverse suggests that the object underwent modifications, such as the addition of the socket and suspension rings, after its initial production.
Identification
- Inventory Number
- 86082
- Source note
- Facts transcribed from the linked source listing or collection record. Attribution and specifications are source-reported and have not been independently authenticated.
Catalogue references
No catalogue numbers recorded. Numbers are only published once transcribed from a verified edition of a standard catalogue — they are never inferred.
Research required
- Research required: The exact type of gnomon and its mounting method remain unclear
- Research required: The magnetic needle and compass glass are missing from the central bowl