This apparatus is composed of a 7 cm long brass calorimetric cylinder width 5 cm and supported by ball bearings. A copper ribbon is rolled around the cylinder and retained by a spring; a 5 kg weight hangs from it. Because of the friction between the ribbon and the cylinder during the rotation, the water inside the cylinder arms up. If you measure the work done and the heat produced, it is possible to determine the mechanical equivalent of heat. The apparatus is supplied with boss-heads and 1/10 degree digital thermometer.