Theodolite - Chasselon , Règle à éclimètre avec niveau optique , Instrument d’optique et de précision - 1940-1950 - France

A theodolite is a precision optical instrument used primarily for surveying and engineering to measure horizontal and vertical angles. This particular model, a Chasselon theodolite equipped with a règle à éclimètre (a type of graduated ruler), an optical level, and dating from the 1940s-1950s in France, represents an important era of manual surveying before widespread electronic devices. The instrument combines glass optics with finely crafted mechanical parts, enclosed often in a protective case, to provide accurate angle readings for mapping land contours and construction sites. Such tools were essential in civil engineering and topography, enabling professionals to make detailed measurements relied upon for infrastructure projects. Collectors and historians value these instruments for their craftsmanship and their role in the evolution of precision surveying technology.