Surveyor's square with compass, antique measuring instrument 19th century

Square of Surveyor With Compass, Instrument Measuring Antique 19th. The description of this item has been automatically translated. Old octagonal brass surveyor's square with compass. This is a very beautiful scientific instrument, surveyor's tool. The surveyor's square is a cylinder or octagonal prism pierced with longitudinal slots and used to trace straight and perpendicular lines on the ground, using markers. The opposite openings are formed either by a narrow slit or by a rectangular opening divided in two by a silk thread. The visual ray passing through this slit, and the silk thread covering a marker placed at any point, these three points serve to determine the position of a straight line. The square is marked "SL", the acronym of the SOCIÉTÉ DES LUNETIERS which produced glasses, compasses, various scientific and marine instruments at the end of the 19th century, now known as " Essilor ". Scientific, vintage and original collector's item in the spirit of cabinets of curiosities. In good condition, in its original condition with traces of age and wear.

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