The thermometer includes a temperature sensor (2) with constructional elements especially lead wires (3) for which heating and cooling facilities (4) are provided. Preferably, the heating or cooling elements can function at the same time as temperature sensors for the heating or cooling system. The functions of heating, cooling and internal temperature measurement can be accomplished by a contact zone between two materials with different contact potentials. The temperature control for the constructional elements can consist of non automatically controlled cooling and automatically controlled heating so that temperature can be set at levels both below and above the ambient temperature level.
