Lee's Disc Apparatus is designed for the measurement of thermal conductivity in bad conductors. Thermal conductivity is the property of a material that indicates its ability to conduct heat. Consisting of a cylindrical brass  disc  of 11.5cm diameter and 12mm thick suspended by three strings from  a ring held in a stand. A thin circular disc of the test material is placed between this slab and 5cm deep hollow cylindrical brass vessel of the same diameter The hollow vessel has two ports, one close to the bottom and the other close to the top of the vessel for inlet and outlet of steam respectively. The brass disc at the base and the cylindrical drum at the top have holes drilled in them for inserting thermometers.  The flat surfaces of the meta disc and hollow cylinder are nickel plated and polished to ensure constant and uniform heat transfer. Supplied with three suitable test specimens (glass, cardboard, and bakelite), without thermometers.