This solid apparatus is composed of a 7cm long brass calorimetric cylinder, 5cm in width, supported by ball bearings. A copper ribbon is wrapped around the cylinder which is retained by a spring with a 5 kg weight hanging from it. Because of the friction between the ribbon and the cylinder during the rotation, the water inside the cylinder warms up. If you measure the work done and the heat produced, it is possible to determine the mechanical equivalent of heat. The apparatus comes complete with boss-heads and 0.1° digital thermometer.