A high-quality apparatus to determine precisely the coefficient of expansion of various metals. An aluminum channel carries a 60 cm long metal rod enclosed in a heating jacket having three nipples for water intake, water outlet, and thermometer insertion. Dial indicator is a precision instrument sensitive to 0.01 mm/division and is securely mounted. As the apparatus works with hot water, there is no danger of any steam escaping and causing burns on the skin. Complete with four expansion rods of steel, brass, copper, and aluminum.