Device used by Cesare Lombroso at the end of the 19th century to detect changes in blood pressure during deception, though the hydrosphygmograph that had been invented years earlier for medical purposes. It consisted of a container of water and a rubber seal through which an examinee’s fist was placed into the water. Once the container was sealed, changes in relative blood volume changes were transferred to the closed system and could be recorded with tubing leading to a recording pen that wrote on a smoked drum. This is the first mechanical device reported in the literature used specifically for deception tests. See: Trovillo (1939).