Consisting of a metal rod, 500mm in length and 4.5mm diameter, enclosed in a well lagged, nickle plated brass tube with three tubules for steam, inlet, outlet and thermometer. The metal rod to be studied is supported in the steam jacket by detachable conical cups situated at each end of the tube. The apparatus is carried on a heavy gauge channel base, at one end of which is an adjusting screw. At the opposite end is a micrometer screw reading to 0.01mm for measuring the expansion. Supplied complete with copper, brass & iron rods but without thermometer.