Description

Theodolite signed “L. Damerÿ A Bruxelles“.

Dimensions : diameter 18,8 cm x height 24,9 cm. 

Provenance: Antiquités Scientifiques Marc-André & Marlyse Perret, Geneva.

In the form of a Greek cross inscribed in a circle, with four fixed pinnules. On this face, three scales (from outside to inside): for degrees (360°), clockwise starting from the right, numbered every 10°; a shadow square, inscribed VMBRA VERSA twice, and a third scale to construct regular polygons: Polÿgons Interns, Polÿgons Externs, and the signature: L. Damerÿ A Bruxelles.

The inner circle, also inscribed: VMBRA VERSA twice, MEDIA twice and VMBRA RESTA (sic) twice. In the four starts of the cross, the four cardinal points: SEPTEMTRIO, ORIENS, MERIDIES and OCCIDENS. The alidade, with two pinnules, attached to the instrument by a nut in the shape of a Greek cross that is typical of the Coignet workshop in Antwerp. The theodolite is mounted on its fixing ball.

Gemma Frisius was the inventor of this type of surveying instrument to measure horizontal and vertical angles. It is described in his Libellum locorum describandorum ratione (1553), which was included in the German edition of Peter Appian’s Cosmographiae (1^st ed., 1529). Michel Coignet* refined the method by adding a tangent rule.

There are other simple Damery theodolites in the Adler Planetarium in Chicago, one in the Musées Royaux d’Arts et d’Histoire in Brussels, one in the Roussel Collection, sold in Paris in 1911, and one in the Rosenheim Collection, sold at Sotheby’s (May 1923, current whereabouts unknown).

Made in Bruxelles circa 1610.