Cistern barometer mounted on a wooden base. The mercury level is adjusted by means of a screw acting on the leather bottom of the cistern. The cistern is enclosed in a box placed at the base of the instrument. The barometric scale, fitted with a vernier, is divided into millimeters. There are three thermometers with centigrade scales: one is inserted into the cistern; a second, of the same shape, is partially immersed in the mercury at the top of the barometric tube; the third and largest is fixed to the wooden base.