IPT 7 final fight, round three

Round three of the 7th International Physicists Tournament final fight at the Faculty of Physics, University of Warsaw. The team of Ukraine reports on problem no. 1, Thermal clock. The problem states: Construct the most precise clock that uses a periodic change of temperature of one of its components as a timer. It should use a continuous heat supply and the working substance may be air or water in any form. The device should not have any moving parts (such as pistons or For the final results an