Coenraad Metz (Danzig 1643-65, Amsterdam 1665-1711).

18th century Dutch land-surveyor with a Holland Circle.
18th century Dutch land-surveyor with a Holland Circle.
The Metz family members with their known relationships. [Rooseboom 1950].
The Metz family members with their known relationships. [Rooseboom 1950].

Metz, Amsterdam

Instrument maker family with many members. Since the instruments are not dated and not always signed with the initials, it is often not possible to accurately determine the maker, especially since two genera bore the same name. The family members with their known relationships is shown schematically on the left.

 

Fig.1. Magnificent little silver half-circle protractor, graduated into half-degrees intervals, and marked by 10s moving in both directions from 0 to 180. The inner scale, indicated in Latin Anguli Poliigonorem Regular, is marked with positions for regular polygons from 3 to 12 sides. The unusual spelling of Poliigonorem is also engraved on a Holland Circle by Coenraad Metz at the now defunct Time Museum in Rockford, Ill. Base 85mm, 55mm from the base to the apex.  

Fig.2. Small brass half-circle protractor graduated in degrees with hand-engraved numbering. The inner scale, indicated in Latin Anguli Polygonorem Regular, is marked with positions for regular polygons of between 3 and 12 sides. Base measures 68mm, height 45mm.   

Fig.3. Holland Circle, unsigned, possibly by Metz, uncertain dating 1650-1750. The compass needle and glass cover is missing. Diameter is 154mm.

In the late 16th century, a Dutch scholar and instrument maker named Gemma Frisius suggested that a good surveying instrument could be made by attaching a magnetic compass to the back of an astrolabe. Building on this idea, Jan Dou designed an instrument with two pairs of fixed sights attached to a graduated circle, and another pair of sights attached to either end of a movable alidade. Dou published an account of this instrument in Dutch in 1612, and the form became popular with surveyors in the Netherlands. The name Holland Circle was coined in the 19th century. The Holland Circle is similar to but easily distinguishable from the common theodolite. 

Fig. 4. to 5. Semi-circular brass protractor with on its base a scale of 3 Rheinland inches (scale length is 78.5mm) and transversal reading to 1/10ths and marked 3/12 Pedis Rhenolandici. A Dutch Rheinland inch equals 2.61cm and is 1/12 of a Rheinland foot. The protractor has two scales running from 0 to 180 degrees in opposite directions, and subdivided to 1/4th degrees. The inner scale of the protractor is marked Anguli Polygonorum Regular and indicates the angles of regular polygons from 3 to 12. The protractor measures 154.5mm at its base and from the base to the apex 105mm. Except for a lacking signature, this protractor is virtually identical to the Metz protractor V09806 at the Boerhaave Museum in Leiden [1]. Probably early 1700s.

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NOTES / REFERENCES

[1] The silver protractor, although much smaller, is similar to the protractor attributed to Coenraad Metz in Museum Boerhaave. 

[2] The brass protractor is similar to the one in a set of drawing instruments attributed to Coenraad Metz at the Fries Scheepvaart Museum in Sneek. 

[3] ROOSEBOOM, M. 1950. Bijdrage tot de Geschiedenis der Instrumentmakerskunst in de Noorderlijke Nederlanden tot omstreeks 1840. p. 97-100.

[4] DAUMAS, M. 1972. Scientific Instruments of the 17th & 18th Centuries and their Makers. p. 87, 249.

...Coenraad Metz (the elder) was born in Danzig in 1643 and settles in Amsterdam in 1665. He worked for de Volder and made a sextant on the model of that of Tycho Brahe for the sum of 1,050 florins, as well as mathematical instruments for the observatory in Leiden. He is well known and highly esteemed by Dutch scolars. He died in about 1711, his workshop being taken over several years later by his grandson, Coenraad Fibus Metz.

[5] POULS, H.C. 2004: De landmeter Jan Pietersz. Dou en de Hollandse Cirkel, Delft. p. 71.

[6] VAN CITTERT, P.H.,1954; Astrolabes, a critical description of the astrolabes and quadrants in care of the Utrecht University Museum, Leiden. plates XXII and XXIII.

[7] ZUIDERVAART, Huib J. 2007; Telescopes from Leiden Observatory and other Collections 1656-1859 A Descriptive Catalogue.

[8] POULS, H.C.; Een nuttig en profijtelijk boekje voor alle geografen. Gemma Frisius. Nederlandse Commisiie voor Geodesie - Stichting De Hollandse Cirkel, 1999.