Siphon and cistern barometer mounted on a tripod with leveling screws. The cistern has a screw that, acting on its leather bottom, adjusts the level of the mercury in a small tube forming the shorter arm of the siphon. The barometric tube is enclosed in a brass tube with windows for reading the mercury level. The brass tube is engraved with four different barometric scales. The readings are taken with a vernier. A mercury thermometer with centigrade and Réaumur scales is also fixed on the brass tube.