This apparatus is used to Verifying the Boyle’s law when air is decompressed and compressed. A horizontally mounted acrylic tube having a graduated scale (0- 300cm3) along one side. A gas tap closes the tube. Pressure gauge is present next to gas tap. By changing the position of rubber stopper, the effective length of the tube can be selected. The scale measures volume and pressure by means of pressure gauze. Boyle’s law is investigated by changing position of the stopper.