Brass graphometer signed "Petrus Jermanini f. Mutinae".
It features an openwork main plate engraved with three scales: the first from 0 to 180 degrees, the second from 180 to 0 degrees and the third a non-linear scale graduated 0-100-0-100-0.
The vertical arm of the turntable is engraved with a cartouche bearing the signature surmounted by a grotesque. At each end of the scales are Renaissance decorations: a grotesque head with ammonite-shaped ears, surmounted by a leafy branch, and a beautifully carved sight. In the lower part of the main plate, in the center, is a compass with a silvered base engraved with an 8-direction compass rose, topped by a blued steel needle with brass pivot, all covered with glass. Around the compass swivels a mobile arm with two sights for reading the graduations on the main plate.
On the back is the ball-and-socket joint, set into its support tube with its clamping screw.
In its original wooden case covered with stamped black leather. The interior is covered with a faded red chamois.
Note: this instrument is used to measure angles between objects in the same plane. It is an instrument for geodesy and topography.
Dimensions :
- Graphometer: length of 19,5 cm x height of 12,8 cm
- Box: length of 22,5 cm x width of 13,5 cm x height of 9 cm
Datable first half of the 17th century.
Reference : D / L2
Price and additional photos on request.
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