Description
An interesting brass graphometer, unsigned, but French, of fairly early production around 1640-1660, with, in the center of the semi-circle, a shadow square.
The instrument measures 26cm in diameter and 14.3cm in height.
The semicircle is divided into two times 180 degrees, all degrees. In the center of the semi-circle a shadow square bears the inscriptions “Umbra Recta” and on its two sides “U[mbra] versa”. It is divided four times from 10 to 100 degrees.
The mobile alidade carrying a division from 90 to 0, then a short scale 0 to 100.
The semicircle has been cleaned and varnished. The four pinnules were formerly remade in oxidized steel or brass.
Part of the ball joint was also previously remade in pink steel: the plate joining the ball joint to its foot and the butterfly screw.
Despite these defects and restorations, elegant graphometer, very well divided, nicely engraved and beautifully cut, from the mid-17th century.
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Dealer information
Le Zograscope
Established by Alexandre Piffault in 2014 and based in Paris at 5 rue de Condé, 75006, very close to Odéon, Le Zograscope specializes in antique and rare books in Science, Medicine and Technology, and rare antique instruments in the same fields. We have especially a strong interest in early and continental microscopy, early and special mathematical/drawing instruments, medical and surgical instrument, and rare technology.
Personnal website : https://www.lezograscope.com/