A rare early 20th century "Sphygmometer de Sir Francis R Cruise" by Collin who was a well know French instrument maker. Cruise's instrument uses an anaeroid manometer to demonstrate the blood pressure. The instrument was held vertically over the supinated wrist by the red Bakelite handle between thumb and forefinger. The lower end of the manometer would be placed on a bulb over the radial pulse. Pressure downwards through the handle was measured on the dial and the reading would be taken at the point at which the radial pulse disappeared.