`Cyrtograph de Bernard', circumferential chest measurer, or cyrtometer, for making measurements in the diagnosis of pulmonary tuberculosis, brass, by Mathieu, Paris, 1830-1880

A cyrtometer measures or traces the outline of curved surfaces of the body. This chest measurer is described as a ‘Cyrtograph de Bernard’. It hinges at the back to open up and surround the chest. 14 adjustable slides then measure the circumference of the patient’s chest. It also monitored the chest’s movement during breathing. This helped diagnose medical conditions including tuberculosis. It was made by French instrument maker Mathieu in Paris between 1830 and 1880.