For demonstrating the relationship between pressure and temperature of a given mass of gas at fixed volume, i. e., Charle's Law. Comprising Jolly's Air bulb connected to a glass mercury reservoir through flexible rubber tubing. The vertical section has a scale graduated 0-100cm x 1 mm, reading in both directions for reading the levels directly. Mercury reservoir tube mounted on vertical support rod with the help of sliding bracket that can be positioned anywhere along the length of the rod. Can also be used as Boyle's law apparatus by using a glass tube with one closed mounted on a slider that slides vertically in slot provided alongside meter rule. Complete with pressure rubber tubing and set of 2 glass tubes. Supplied without mercury.