Graphometer With Double Sighting Glasses Signed Richer Dated 1808

Beautiful graphometer with double glasses signed Richer in Paris and dated 1808. It is equipped with its ball jointed foot with adjustments by microscmmetric screw. A double-spectrum graphometer is a measuring instrument used in surveying and geodesy to measure horizontal and vertical angles with high precision. It is also sometimes called a double-scope theodolite. Here is a description and an explanation of its use: The double glasses graphometer is an optical instrument composed of two glasses mounted on the same horizontal axis. Each of these scopes is equipped with a reticle (a type of aiming grid) through which the operator can observe aiming points, such as stakes, milestones or other targets. The graphometer is mounted on a stable tripod and can be leveled to ensure it is perfectly horizontal. It is also equipped with horizontal and vertical graduated circles for measuring angles. The primary use of a double-scope graphometer is to measure horizontal and vertical angles between aiming points.